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   Sex Life Of Figs: Coevolution Of A Tree & Minute Wasp (Part 1)     Part 2  
Perpetuation Of Fig Wasp Which In Turn Perpetuates Fig By Pollination & Seed Production

Fig wasps live, mate & pollinate inside closed, globose or flask-shaped structures called syconia, lined on the inside with minute flowers. We often refer to these structures as fig "fruits." The tiny wasps provide natural pollination & seed production. They are vital to the perpetuation of fig species. The figs, in turn, provide the wasps with food & living quarters "condominiums" inside the syconia. Timing is crucial when emerging, egg-bearing female wasps exit donor syconia and enter receptive syconia on the same or different tree as the seasons pass. This process occurs 3 or more times a year. In the common edible fig there is even an overwintering "mamme" crop when the trees are deciduous. Beneficial wasps must also cope with non-pollinator, bogus fig wasps who take advantage of fig hospitality. Variations in this wasp migration cycle occur in an estimated 900 monoecious & dioecious fig species on our planet, each with one or more unique, symbiotic, pollinator wasps. All of this timing & interaction is controlled by molecular genetics, research that continues to this day. This is why I categorically say that the fig & fig wasp scenario is the most complex interaction between a plant and an insect on Earth! Because of complexity & exceptions between different fig species, oversimplified generalizations often lead to errors in the literature.
© W.P. Armstrong January 2012 (updated Feb. 2023)    Find This Page Again At Search: Top Of   Wayne's Word Home Page
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It is Difficult to Generalize About Fig Biology Because Of All The Exceptions
Table Of Contents For Parts 1 & 2
  1.    Brief Introduction To The Biology Of Figs
  2.    The Rustyleaf Fig & Its Pollinator Wasp
  3.    Life Cycle Of Common Fig (Ficus carica)
  4.    Important Definitions Used In Fig Biology
  5.    Roles Of Male Wasps In Fig Life Cycle
  6.    Discrepency In Monoecious Style Length
  7.    Annual Crops Of Edible Fig Syconia
  8.    Time Lapse: Caprifig Crops & Wasp Survival
 8A.   2022 Receptive Mammoni & Winged Wasps
 8B.   Parthenocarpic Caprifig Mammoni Syconia
 8C.   Caprifig Wasp & Pollen-Bearing Mammoni
 8D.   Mammoni With Seed-Bearing Endocarps
 8E.   Wasp Exodus From Purple Mammoni 31 Aug
 8F.   Immature Profichi Feb 2023 From 2022 Branch
  9.    Persistent vs Caducous Syconia
 10.   RNA Transcriptomic Analysis
 11.   Pollinated Parthenocarpic Figs With Seeds
 12.   Hunting For Wild Seedling Figs In California
 13.   F. pseudocarica - F. palmata Controversy
 14.   Carica/Palmata Complex & F. carica Origin?
14A.  8 Wild Species In Carica/Palmata Complex
15.    Sex Determination In Trees Of Ficus carica
16.    Calimyrna Orchards In San Joaquin Valley
17.    Drupelets: True Botanical Fruits Of A Fig
18.    Overwintering Mamme Crop Of A Caprifig
19.    Why Female Wasp Can't Oviposit In Edible Fig
20.    Vicarious Selection: Coevolution Of Fig & Wasp
21.    Parthenocapic Varieties Of Ficus carica
22.    Dangers Facing Emerging Female Fig Wasps
23.    Which Figs Grew In The Ancient Holy Land?
24.    Fossil Fig Syconia In Wyoming & Montana?
25.    Links To Articles About Figs On Wayne's Word
26.    Reference Articles Cited In Wayne's Fig Articles 

Following Links On Different Wayne's Word Pages:

  1.    Fig Species In Palomar College Arboretum
  2.    Unusual Ficus dammaropsis Of New Guinea
  3.    Additional Figs In Palomar College Arboretum
  4.    Banana Fig (F. pleurocarpa) At Palomar College
  5.    'Vista Caprifig' Wayne's Word Twin Oaks Valley

Ficus cf. pseudocarica 'vista' = 'Vista Caprifig'
This Clone Discussed In Following Paragraphs

Note: The seedling caprifig that I transplanted from a roadside creek in Vista, California is a noteworthy hybrid. In my opinion, it is different from typical F. carica, and keys out fairly close to F. pseudocarica in Condit's classic books The Fig (1947) and Ficus: The Exotic Species (1969). It also appears slightly different from original F. pseudocarica discussed in the literature. I have propagated clonal cuttings to several fig growers in California and the campus of Palomar College. In order to distinguish this very productive clone, I refered to the specific epithet "pseudocarica" preceeded by the abbreviation "cf" and followed by 'vista' in single quotation marks. In fact, this name appears on some of my images. However, considering the complexity of this controversial taxonomy, I have decided to refer to this clone as 'Vista Caprifig' throughout the text on this page.

  Gall Flowers In Figs  

The distribution of an estimated 900 species of Ficus are shown in the green area of above map. Figs occur throughout the Old and New World tropics, extending north to the eastern Mediterranean and China. By far the majority of species are evergreen. The common fig (Ficus carica) is deciduous and grows in colder climates of Turkey and the Middle East. With the exception of the Hawaiian Islands, practically every tropical continent and major island group has one or more species of indigenous fig. In fact, the tiny island of Barro Colorado in the Panama Canal Zone, with an area of only six square miles, has 17 native species. Virtually every species of fig has its own unique species of "in house" wasp pollinator. The wasps are housed throughout the year inside the fig's hollow syconia, in one of nature's most remarkable symbiotic relationships between a tree and an insect. The symbiotic wasps undoubtedly play a major role in the ability of different fig species to grow in the same locality, a phenomenon known as "species packing."

The earliest official published binomial for the common edible fig is Ficus carica L., authored by Linnaeus in Species Plantarum (1753). There are a number of other published binomials in the literature that are later synonyms of F. carica. Linnaeus is also given credit for naming the symbiotic pollinator wasp of F. carica, Blastophaga psenes, although he originally named it Cynips psenes in 1758. The basionym Cynips is the type genus in the gall wasp family Cynipidae that includes about 800 species, most of which occur on oaks (Quercus). In fact, some naturalists thought that mature fig syconia releasing wasps were actually galls. The term "gall flower" for wasp-bearing flowers within fig syconia is used in the literature today. Most authors now place Blastophaga in the fig wasp family Agaonidae. With one or more species of symbiotic pollinator wasp per fig and 900 species of figs, this is truly one of the most complex examples of coevolution between a plant and an insect.

    Kew Plants Of The World Online    
World Flora Online Home Page
World Flora: Araucariaceae

1. A Brief Introduction To The Biology Of Figs

In the late 1960s, many of the old brick buildings on the campus of Palomar College were covered with creeping fig (Ficus pumila), giving the campus a beautiful ivy-league appearance resembling the Engish ivy (Hedera helix) that covers walls and buildings of universities in the eastern United States. I began studying figs at that time, and after 40 years of teaching botany classes, I have concluded that the figs are the most remarkable trees on earth. The Plant List of Kew and Missoutri Botanical Garden (2011) gives 830 accepted species of Ficus, and they all have their own in-house pollinator wasp. Most species are evergreen and occur in rain forests throughout the tropics. They are a major factor in tropical ecosystems, providing sweet fruits for numerous animals, including parrots, hornbills, toucans and monkeys. Fruit-eating bats commonly disperse the seeds in their excrement, and seedlings often start out as epiphytes on branches high in the rain-soaked canopy. The common edible fig (F. carica) is deciduous and extends north into temperate regions of Europe and the Middle East. The many uses of figs by people is legendary, and there is good evidence that the common fig was one of the earliest cultivated trees. Depending on the reference, there are an estimated 400+ cultivated varieties of the common fig.

  Kew List Of Plant Species:  

The creeping fig (Ficus pumila) of eastern Asia. There are two distinct types of stem growth: Young, juvenile branches and older, mature branches. The juvenile branches with smaller leaves (top) produce aerial roots that adhere to concrete, stucco, masonry and even glass windows. Without pruning, a single plant can envelop a four-story building. The syconium is lined with all long-style female flowers. Without pollen-bearing male plants and fig wasps, no seeds can be produced and this plant must be propagated by cuttings. In its native habitat there are also male plants (caprifigs) with male flowers and wasp-bearing female flowers. When I began teaching at Palomar College in the late 1960s, this fig covered many of the old brick buildings. The campus truly had an "ivy-league" appearance, except our "ivy" was the creeping fig. The new growth had to be constantly trimmed around windows and doors, and eventually all the plants were removed by the gardening staff.
Creeping fig (Ficus pumila): Close-up view of the aerial roots (red arrow) that develop at the nodes on juvenile branches. The aerial roots secrete a clear, gummy latex that works like rubber cement. The roots adhere to concrete, masonry and glass. This remarkable adhesive was first described in detail by Charles Darwin in his book The Movements and Habits of Climbing Plants (1876). Older, mature branches with larger leaves produce flower-bearing syconia. This species is commonly planted in southern California to cover the monotanous concrete walls of buildings and freeways. In fact, it was been crossed with the edible fig (F. carica) to produce a hybrid vine (F. x pumila-carica). Unfortunately, the hybrid produces inedible syconia and lacks the adhesive aerial root pads. The hybrid is a sprawling vine that can grow on fences but cannot cling to vertical concrete walls like its F. pumila parent (see next image).

Ficus x pumila-carica: A hybrid between the creeping fig (Ficus pumila) and the common edible fig (F. carica). It has leaves and syconia intermediate between the parents; however, the syconia are basically inedible compared with F. carica. In addition, the hybrid lacks the adhesive aerial roots of F. pumila.

2. Rustyleaf Fig (Ficus rubiginosa) & Its Remarkable Pollinator Wasp

All figs rely on tiny symbiotic wasps for their pollination. Minute male and female fig wasps are borne inside hollow, fleshy, flower-bearing structures called syconia. The syconium is what most people associate with the tasty fruit of a fig, but technically it is not a true fruit. The syconium is lined on the inside with hundreds of tiny male and female flowers. The flowers are greatly reduced and do not have petals. Male flowers consist of pollen-bearing anthers. Female flowers are of two types: Long-style, seed-bearing flowers and short-style flowers that bear fig wasps instead of seeds. Wasp eggs are not laid in the ovaries of long-style flowers because the wasp's ovipositor cannot reach the ovary.

A. Close-up view of a male and female fig wasp (Pleistodontes imperialis) that inhabits the syconia of the Australian rustyleaf fig (Ficus rubiginosa). The slender ovipositor on female wasp is too short to penetrate the ovary of long-style flowers; therefore she does not lay eggs in these flowers. The smaller, wingless male has large mandibles and a greatly reduced body which has two primary purposes: (1) Inseminating the female and (2) Chewing exit tunnels through the syconium wall through which the females escape. The "eye" of an ordinary sewing needle is shown for a size comparison. These wasps were collected from trees growing by the old Life Science building. The biology students were always amazed when I brought them into my laboratory classes.

B. A non-pollinator "bogus" fig wasp collected from the syconium of the Baja California wild fig (Ficus palmeri, or possibly Ficus brandegeei). The ovipositor is much longer than the symbiotic pollinator wasp. In fact, some non-pollinator wasps can penetrate the entire syconium wall from the outside. Non-pollinators can also lay eggs in long-style fig flowers reserved for fig seeds. Consequently, no seeds are produced in these flowers. In addition, these "bogus" fig wasps do not pollinate fig flowers. Although they do not benefit the fig tree, non-pollinator wasps of the families Torymidae and Eurytomidae are common inhabitants of New World monoecious fig syconia. Their coexistence with natural fig pollinator wasps is a complex and perplexing coevolutionary problem in fig biology.

  Size Of Sewing Needle In Wayne's Word Images  
Ficus palmeri In Mtns & Coastal Baja California

Fig species have one or more pollinator wasps in the family Agaonidae that enter their syconia through a small opening called an ostiole to pollinate the female flowers inside. Although pollinator wasps are often host specific, one pollinator can have more than one host (J.M. Cook and J.-Y. Rasplus, 2003). In addition, the syconium may contain one or more non-pollinating wasps in a different wasp families. Like the pollinator wasps, the nonpollinators have flattened heads and bodies, and are perfectly adapted to squeeze between the ostiolar bracts of receptive syconia. This is yet another example of convergent evolution. Without the pollinator wasps transferring pollen from one syconium to another, the female flowers inside would not get pollinated and no seeds would be produced (a catastrophe for the fig tree). In the common edible fig (Ficus carica), the female wasp gets covered with pollen as she exits the male caprifig. In many tropical fig species, the wasp packs her pollen baskets (corbiculae) on the underside of her thorax before leaving the syconium. When she enters another receptive syconium, she transfers her load of pollen to the female flowers inside. I have observed this latter scenario many times on rustyleaf figs on campus. Unfortunately, most of these trees were cut down to make room for new buildings. Hopefully, some of these wasps have made their way to the Arboretum.

A 34 million-year-old fossil fig wasp from the Eocene was dicovered in limestone on the Isle of Wight, England (Stephen Compton et al. 2010). It was originally thought to be a tiny winged ant, but was later confirmed to be a female fig wasp because of the pair of pollen baskets (corbiculae) on the underside of its thorax. The corbiculae of this wasp named Ponera minuta even contained Ficus pollen. The previous record for ancient fig wasps was 23 million-year-old Dominican Republic amber from the Miocene. DNA phylogenetic analysis indicates that the fig and fig wasp relationship may extend back more than 65 million years ago to the Cretaceous Period. The Isle of Wight fig wasp is relatively unchanged compared with present-day fig wasps of the family Agaonidae. "No innovations in the relationship are discernible for the last tens of millions of years." According to Nefdt and Compton (1996) short-style female flowers in moneous figs have longer styles than those in male figs of dioecius species. The shorter ovipositor of Ponera minuta indicates that its symbiotic host was dioecious, an advanced reproductive pattern in fig evolution.

Fossil leaves embedded in 60 million-year-old limestone from the Fort Union Formation near Glendive, Montana have tentatively been identified as Ficus. Fossil fig syconia named Ficus ceratops from the 70 million-year-old Hell Creek Formation in this area have been clearly shown to be a different species, possibly an extinct palm. See Section 17 on this page: Fossil Fig Syconia in Wyoming and Montana.

3. Life Cycle Of The Common Fig (Ficus carica).

Life cycle of the common fig (Ficus carica). Style length is genetically determined and it is vital that syconia on seed-bearing female trees have styles longer than the female wasp's ovipositor. Unable to reach the ovaries of these flowers, she does not lay eggs (oviposit). Therefore, a seed develops inside the ovary rather than a hungry wasp larva. She can only oviposit in the short-style female flowers on "male" trees called caprifigs. Caprifig trees produce pollen and the crucial pollinator wasps (Blastophaga psenes). In some common figs termed "caducous" or early deciduous, the immature female syconium drops from the tree if the flowers inside are not pollinated. There are many cultivated "parthenocarpic" varities of the common fig in which the syconia develop on female trees wthout wasp pollination (caprification). The ripe syconia are fleshy and edible; however, the numerous ovaries (drupelets) inside are hollow and seedless.

More Detailed Image Of Ficus carica Male & Female Flowers

4. Some Definitions Used In Fig Biology

Style Length-Ovipositor Length Hypothesis: This refers to oviposition through style of female flower by pollinator wasp. Wasp ovipositor can penetrate ovary of short-style flower where egg is deposited. Ovipositor is too short to penetrate ovary of long-style flower. Consequently, wasp larvae occupy ovaries of short-style flowers while seeds develop in ovaries of long-style flowers. This mechanism limits seed predation in dioecious figs, but may not hold true in most monoecious figs.

Hypotheses For Limiting Seed Predation In Monoecious Figs:

  1. Stigma morphology controlling preferential oviposition.
  2. Aborting syconia with too many parasitized seeds.
  3. Limiting number of pollen-bearing wasps through ostiole.
  4. More ovaries in syconium than wasp can oviposit in.
  5. Short life span of pollen-bearing female wasps (foundresses).
Gall Flower = Short-style Female Flower: Oviposition and the presence of a wasp larva initiates the development of endosperm tissue that the larva feeds on. Since pollination is not required, the developing wasp-bearing ovary is called a gall. This relationship is seen in the ovaries of Ficus sycomorus inhabited by the nonpollinator wasp Sycophaga sycomori. It is also seen in the overwintering mamme crop of F. carica caprifigs where developing wasp larvae feed on endosperm tissue from unpollinated flowers. According to some fig biologists, since the normal course of events is to abort unpollinated syconia in caducous figs, the entire syconium could be viewed as a gall occupied by nonpollinator wasps. [Some fig biologists also state that the short-style flower is pollinated and the larva feeds on the endosperm of developing seed.] According to Storey (1977) the term "gall flower" is a misomer because it is fully capable of producing normal seed-bearing drupelets if pollinated, and in this respect are no different from long-style flowers. I tend to agree with Dr. Storey. This subject was originally published by Drs. I. J. Condit and S. E. Flanders in 1945 (Science 102: 128-130).

  Gall Flowers In Figs  

Foundress: Gravid, pollen-bearing female pollinator wasp that enters ostiole of specific syconium during receptive stage.

Parthenocarpy: Development of the ovary of a flower without pollination and fertilization. In figs, this refers to the hollow, seedless drupelets (cenocarps). In figs the outer syconium also develops.

Stimulative Parthenocarpy: Development of the drupelet by the oviposition and habitation of wasp larva. Since the egg and embryo sac is destroyed in the process, the nutritive nucellar and endosperm tissue that the larva feeds on develops without fertilization. The resulting drupelet is a hollow psenocarp bearing a wasp larva.

Vegetative Parthenocarpy: Development of drupelets and syconium without pollination, fertilization or any known stimulus. The drupelets are hollow cenocarps. This is characteristic of common figs with the persistent gene. These figs do not require pollination by a fig wasp (caprification); however, they are fully capable of producing seed-bearing drupelets if they are pollinated and fertilized.

Parthenogenesis: Development of the egg into an embryo without fertilization. This also applies to the development of endosperm tissue without fertilization of the two polar nuclei within the binucleate endosperm mother cell. Parthenogenetic endosperm tissue in figs has the same chromosome number as sporophtye tissue (2n = 26) according to Saleeb (1965).

  Apomixis: Parthenogenesis & Agamospermy  

Syconium: An inside-out inflorescence composed of a hollow, fleshy structure (peduncular tissue) lined on the inside with hundreds of tiny unisexual, apetalous flowers. Some authors state that it is composed of receptacle tissue, but Storey (1977) states that this is incorrect. Some authors refer to the syconium as a compound or multiple fruit because it contains many ripened ovaries derivied from many separate flowers. The actual fruits of a fig are the one-seeded drupelets that form inside wasp-pollinated syconia.

Neck: Slender part of syconium body attached to a stalk (peduncle) at its base.

Drupelet: The actual fruit from the ovary of a long-style female flower, composed of a sclerified endocarp surrounding the seed. It is erroneously called an "achene." An empty drupelet which develops parthenocarpically (without fertilization) is called a Cenocarp. A wasp-bearing drupe in the caprifig is called a Psenocarp.

Protogynous: Female flowers are receptive before male flowers mature and shed pollen. This strategy favors cross pollination and is typical of monoecious fig syconia and "male" syconia of dioecious figs.

Geitonogamy: [guy-ton-OG-uh-mee], Self pollination between different flowers on the same plant with genetically identical gametes. In some monecious figs and mammoni syconium of dioecious Ficus carica caprifig.

Caprification: Pollination of a female fig (Ficus carica) by fig wasps in order to produce mature seed-bearing syconia. Without pollination, Smyrna-type (caducous) syconia will fall from the tree without ripening.

Monoecious: Fig species with pollen-bearing male flowers, short-style female flowers and long-style female flowers in the same syconia. This includes about half of the world's fig species, the other half being dioecious with separate male and female trees. Measurements of styles and pollinator ovipositors show that most ovules in most monoecious species are within the wasp's reach (Herre, andér and Macado, 2008). This significant revelation indicates that other mechanisms are involved in the determination of seed-bearing and wasp-bearing ovaries. This is quite different from Ficus carica and other dioecious species. Monoecious figs are considered to be the ancestral breeding system, dating back at least to late Cretaceous (70 million years ago) to the time of T-Rex. Again, it is extremely difficult to generalize about fig biology because of all the exceptions.

Gynodioecious: Fig species with male and female trees in the population. Male trees (caprifigs) bear "male" syconia containing pollen-bearing male flowers and short-style female flowers. The ovaries of short-style female flowers often contain a male or female wasp larva if eggs were oviposited inside them. Female trees only bear female syconia containing seed-bearing long-style female flowers and no male flowers. About half the world's 830 fig species are gynodioecious, the other half being monoecious with male flowers, short-style and long-style female flowers in the same syconium (i.e. without separate male and female trees).

NYBG Steere Herbarium Definition of Gynodioecious: Sexual condition of a species that bears pistillate flowers on some plants and bisexual flowers or staminate flowers as well as pistillate flowers on other plants. The important word here is "or" rather than "and" [e.g. Fig (Ficus) & Mulberry (Morus)].

Pollen Basket (Pollen Pocket) = Corbicula: A specially-adapted cavity often surrounded by fringe of hairs on underside of thorax or base of leg on female wasps where pollen is purposely deposited before exiting the syconium of monoecious and gynodioecious figs.

Coxal Comb: A specially-adapted fringe of hairs on the fore coxae (base of front legs) on female wasps. It is used to actively (purposely) gather pollen from within the syconium and store it in thoracic pockets (pollen pockets). According to Cook, et al. 2004, the presence of coxal combs always indicate active (purposive) pollination behavior, whereas pollen pockets provide a good but imperfect index. Active pollination includes serveral identifiable components: Wasps must collect pollen from anthers, place it into pockets, and deposit it onto receptive flowers. To accomplish this they require coxal combs and pollen pockets. The following paragraph from Cook, et al (2004) illustrates the complexity of pollination behavior, especially Pleistodontes froggatti in the Moreton Bay fig (Ficus macrophylla):

    "Kjellberg et al. (2001) observed pollen deposition behaviour for several species from various fig wasp genera and identified a morphological trait (presence of coxal combs) that always indicated active pollination. This trait is easy to observe and allows inference of behaviour for a much wider set of species than can be observed in the act of pollination. The presence of pollen pockets also generally indicates active pollination, but there are exceptions involving passive species in a genus that is primarily active (Kjellberg et al., 2001). The genus Pleistodontes contains the only species highlighted as a possible exception to the striking general pattern of fig pollinator coadaptation. Ficus macrophylla Desf. ex Pers. has a high anther/ovule ratio, typical of a passively pollinated fig. However, its pollinator, Pleistodontes froggatti Mayr, although lacking coxal combs (suggesting passive pollination), has pollen pockets that can contain concentrated pollen (suggesting active pollination). On balance, this species has been considered an active pollinator in two previous studies (Kjellberg et al., 2001; Jousselin et al., 2003)."
  Pollination Behavior In Different Wasp Genera  

A deceased female fig wasp (Pleistodontes imperialis) extracted from the ostiole of Ficus rubiginosa. Note the coxal comb at the base of front leg that it used to actively gather pollen from syconium and store it in ventral thoracic pocket (pollen pocket). Inset (left): SEM from Kjellberg, F., Jousselin, E., Bronstein, J.L., Patel, A., Yokoyama, J., and J.-Y. Rasplus. 2001. "Pollination Mode in Fig Wasps: The Predictive Power of Correlated Traits." Proceedings of the Royal Society of London 268: 1113-1121.

Syconium of Moreton Bay fig (Ficus macrocarpa) in Palomar College Arboretum. Palomar College horticulturist Tony Rangel grew viable seeds from this tree, so I suspected that the pollinator wasp (Pleistodontes froggatti) must be present.

Unlike the similar P. imperialis of rustyleaf figs (F. rubiginosa), P. froggatti does not have a coxal comb at the base of its front legs. According to Cook, J.M. et al. (2004), the lack coxal combs indicates passive rather than active (purposive) pollination; however, they also state that "pollen pockets provide a good but imperfect index." In Table 1 of their article they state that pollination by P. froggatti is passive. Prior to my discovery of P. froggatti in the Moreton Bay fig at Palomar College (December 2011), the only fig wasps I have documented on campus are P. imperialis on rustyleaf figs and Eupristina verticillata on the Indian laurel fig (Ficus microcarpa).

Pleistodontes froggatti from Moreton Bay fig syconium in Palomar College Arboretum.

Eupristina (Parapristina) verticillata from Indian laurel fig (Ficus microcarpa) syconia on Palomar College campus. One wasp is squeezing through an exit tunnel cut by male wasps (white arrow). Another Fig/Fig Wasp Discrepancy: J.T. Otero and J.D. Ackerman (2002) statistically analyzed the style length of native F. citrifolia and introduced F. microcarpa in Puerto Rico. They found no correlation between style length and seed predation in syconia of these trees: "Neither Ficus species showed significant differences in style length between flowers with wasps and flowers with seeds, as expected under the short-ovipositor-length hypothesis."

It is interesting to speculate on how these symbiotic wasp species were introduced at Palomar College. Were wasp-bearing syconia already present on the original plantings, or were wasps carried here by the wind from trees in neighboring cities? The Moreton Bay fig is native to eastern Australia where it grows in the rain forest and often starts out as an epiphytic vine that develops into a strangler fig. Eventually it shades out and kills its host, becoming a massive tree with a buttressed trunk and huge spreading surface roots. In Hawaii and northern New Zealand it has become naturalized because of the introduction of its pollinator wasp (Pleistodontes froggatti). In Hawaii the wasp was deliberately introduced in 1921. In New Zealand it was first recorded in 1993, having apparently arrived by long-distance dispersal from Australia, a 3,000 km (1900 mile) journey. According to R.O. Gardner and J.W. Early (1996), adult female wasps usually live 2-3 days; there are an average of 21 days over the course of a year during which the wasps could make this trip in 1-3 days on air currents. Fig wasps have been caught in light traps aboard ships up to 99 km (60 miles) offshore in the Pacific (J.C. Harrell and E. Holzapfel, 1966). Ahmed, at al. (2009) reported pollen transfer by the African fig wasp Ceratostolen arabicus between known host trees of Ficus sycomorus separated by a distance of 160 km (100 miles). Based on these records for long distance dispersal, reaching Palomar College in San Marcos from known wasp-bearing trees in coastal San Diego County is certainly plausible. Once in the vicinity of host trees, they are attracted to the correct syconia by mixtures of species-specific chemical attractants, including volatile terpenoids. For example, receptive syconia of F. hispida release blends of three fragrant monoterpenes, including linalool (major constituent), limonene and pinene (C. Chen and Q. Song, 2008).

A single large monoecious fig tree or gynodioecious "male" tree produces several crops of syconia per year. Depending on the species, one crop may consist of hundreds or even thousands of syconia, each bearing a hundred or more pollinator wasps. A large tree, such as the Moreton Bay fig could theoretically release thousands of pollinator wasps into the wind. In fact, during wasp exodus season in Balboa Park, hundreds of fig wasps from nearby trees collect in windows at the San Diego Natural History Museum!

The introduction of symbiotic fig wasps poses a serious problem of invasive strangler figs in tropical regions because of the prolific production of syconia and viable seeds. According to Jennifer Possley, Field Biologist at Fairchild Tropical Botanic Garden, five species of strangler and banyan figs are naturalized in southern Florida, including Ficus altissima, F. benghalensis, F. benjamina, F. microcarpa and F. religiosa. Throughout Key West, seeds of the Indian laurel fig (F. microcarpa) germinate readily in cracks and crevices of old buildings, gradually sending a weblike mass of aerial roots down the walls to the ground. Some residents of the Coral Gables area consider the Asiatic banyan-type figs to be a nuisance and potential menace. The massive, spreading roots of these enormous trees buckle pavement and concrete swimming pools, plug drainage and sewer lines, and pose a serious threat to underground utilities. In other parts of the world alien figs can also invade native rain forest and other plant communities. It should also be noted here that southern Florida and the Caribbean region also have native strangler figs, including F. aurea and F. citrifolia.

Naturalized figs in the Florida Keys. Strangler figs and banyans need viable seeds and a moist climate to be naturalized. Viable seeds require pollinator wasps in their syconia.

  Strangler Figs and Banyans  
Wayne's Word Fig License Plate

Topocentric Pollination: Passive mode where pollen is trapped in intersegmental folds (grooves) as wasps exit the syconium, and is rubbed off as wasps move about on stigmatic platform (synstigma) of new receptive syconium.

Ethodynamic Pollination: Deliberate (purposive) pollen transfer from pollen baskets (corbiculae) to dense stigmas of receptive female flowers (synstigma).

5. Roles Of Male & Female Wasps In Life Cycles Of Common Fig & Rustyleaf Fig

The male & female wasps in above image are Blastophaga psenes from Ficus carica. The exit tunnels were made by male Pleistodontes imperialis in the syconium wall of the rustyleaf fig (F. rubiginosa). Blastophaga males do not cut the exit tunnels through the syconium wall. Instead, the females exit through the ostiole, becoming dusted by pollen from male flowers near the ostiolar end of the syconium.

Patterns Of Collecting Pollen & Exiting Syconium By Female Fig Wasp

Pollen Collection
By Female Wasp
Female Wasps Exit
Through Ostiole
Females Exit Through
Tunnels Cut By Males
Without Pollen Baskets:
Pollen Is Carried In Grooves
Between Abdominal Segments
Passively Dusted With
Pollen From Male Flowers

Some Gynodioecious spp.
e.g. F. carica
Passively Dusted With
Pollen From Male Flowers

Some Gynodioecious spp.
  With Pollen Baskets
(Coxal/Sternal Corbiculae)
  Purposely Packs
Her Pollen Baskets

Some Gynodioecious spp.
  Purposely Packs
Her Pollen Baskets*

Monoecious & Gynodioecious
e.g. F. rubiginosa

* Common Pattern That Fits "Vicarious Selection" Example In Chapter 10 of Richard Dawkin's Climbing Mount Improbable.

  Key To Subgroups Of Gynodioecious Figs  

6. Discrepency In Style Length Hypothesis For Monoecious Figs

According to Carole Kerdelhué and Jean-Yves Rasplus (Oikos Vol. 77: 163-166, 1996), monoecious syconia of Ficus sur contain long-style and short-style female flowers densely packed together in a layer that lines the inner cavity of the syconium. Although the styles all form a relatively continuous stigmatic layer called a synstigma (i.e. all stigmas in the same plane) within the syconium, the ovaries may be deep or shallow relative to the synstigma depending on the length of their flower stalks (pedicels). Generally, the deep-seated ovaries (on short pedicels) with long styles each contain a seed, while the shallow ovaries (on long pedicels) with short styles each contain a wasp larva. A pollinator wasp walking on this "bed" of styles (synstigma) can insert her ovipositor down the short style and easily penetrate the ovary where she lays an egg. The deep-seated, long-style ovaries are out of reach for her ovipositor (style longer than her ovipositor), and consequently these ovaries develop seeds rather than wasp larvae. Because of intermediate style lengths (between long and short) and different ovary heights due to the length of flower stalks (pedicels), the ovary position of female flowers in monoecious fig syconia often forms a stratification. There are at least 4 different ovary layers occupied by beneficial (pollinator) and non-beneficial and/or harmful non-pollinator wasps. These layers are shown by different colors in the following illustration according to their position (depth) from the stigmatic surface (synstigma) within the syconial cavity.

According to Kerdelhué and Rasplus (1996), dioecious figs may have evolved from monoecious ancestral fig species due to selection pressure by non-pollinator fig wasps. Although these non-pollinator wasps belong to the same Order Chalcidoidea as pollinators, many of them belong to different families. They do not benefit the fig and may even be harmful--especially when they compete with and/or parasitize the beneficial pollinator wasps.

Monoecious Figs
     Stratified Syconium: 4 Ovary Positions     
Gynodioecious Figs
     2 Synconia Ea. With 1 Ovary Position     
  Contain (Harbor) more species of competing &  
parasitic nonpollinators. Disadvantage to fig.
  1 ovary position per syconium. Contain fewer  
species of nonpollinators. Advantage to fig.

Heterostyly and four ovary layers (stratification) within the syconium of a monoecious fig (Ficus sur). (1) Yellow: The most shallow ovaries (near surface) with shortest styles which typically contain a pollinator wasp larva; (2) Green and (3) Red: Slightly deeper ovaries that typically contain non-pollinator wasp larvae; (4) Black: The deepest ovaries with longest styles that typically bear mature seeds.
Exception to above illustration: Measurements of styles and pollinator ovipositors show that most
ovules in most monoecious species are within the wasp's reach (Herre, Andér and Machado, 2008).

7. Annual Crops Of Edible Fig Ficus carica syconia

Sex of Tree
Mature Crops Of Syconia Per Year
Male Caprifig
Profichi (June) *
Mammoni (Fall)
Mamme (Winter)
Female Tree
1st or Breba (Summer)
2nd or Main (Late Summer-Fall)

* Only the caprifig Profichi crop produces pollen, and this is used to pollinate
   the receptive main crop in June by the action of winged female fig wasps.
Brebas may be technically defined as the first or spring crop of the pistillate tree that ripen in summer. The syconia develop from latent buds differentiated in fall prior to the onset of dormancy and leaf abscission. On my 'Verte' fig in Twin Oaks Valley, San Diego County, I can usually find a few, rare brebas in May. They are on old, leafless wood of previous growing season, below current growth of leaves and numerous main or 2nd crop of syconia. The main crop ripens in late summer and fall.

Female Trees:
1-2 Crops/Year

Male Trees:
3 Crops/Year

Type Of Gynodioecious Fig Cultivar Based On Sex & Whether
It Needs Caprification (Pollination) In Order To Set Fruit Crop
Unisexual Female Tree (No Male Flowers)
Syconia Contain Long-Style Female Flowers
Male Tree
Crop Name
San Pedro *
Common **
1st or Breba
Profichi ***
2nd or Main
3rd Crop

 * Depending on the cultivar, main crop may develop even if it is not caprified.
 ** There are about 400-500 cultivated varieties of the common fig (Ficus carica).
*** Only the caprifig profichi crop produces pollen, and this is used to pollinate
    (caprify) the receptive main crop of Smyrna & San Pedro type figs in June.

'Vista Caprifig'

Longitudinal section through a caprifig profichi syconium in June showing male flowers.

Ficus cf. pseudocarica 'vista' = 'Vista Caprifig' Profichi Crop in May & June 2021
Photographed In My Yard In Twin Oaks Valley, San Diego Co. [Note: In biological naming conventions, cf. is commonly placed between the genus name and the species name to describe a specimen that is difficult to identify; in other words, the actual species-level identification cannot be certain.]

'Vista Caprifig'

'Vista Caprifig' with green profichi crop in May 2021. The syconia are purple when male flowers shed pollen as pollen-laden Blastophaga psenes females emerge in June. These tiny winged wasps pollinate edible figs in my yard and are responsible for the many naturalized fig seedlings. Pollination by fig wasps is also why Ficus carica is listed in Jepson Manual Vascular Plants of California as naturalized.

The following image shows 'Vista Caprifig' a month later in June with mature pollen-bearing syconia. This is also when mated female Blastophaga psenes wasps exit syconia dusted with pollen. They fly to other figs in my yard, such as 'Verte' cultivar with receptive syconia. Pollination of 'Verte' produces 2nd (main) crop in late summer that are especially delicious with bright, strawberry-red interiors and numerous seed-bearing endocarps.

'Vista Caprifig'
I am very glad I rescued this marvelous caprifig from a roadside creek in Vista, CA.

The inner layer of a minute, ripened fig ovary (drupelet) is called the endocarp. Seed-bearing endocarps of Ficus carica variety 'Verte' sink to the bottom of a dish of water. Although this cultivar in my yard is parthenocarpic, it has been pollinated by fig wasps from a nearby 'Vista Caprifig'. Although unpollinated syconia are very good, they are not as delicious (in my humble opinion) as wasp-pollinated 2nd crop. Endocarps are technically the botanical fruits of a fig because they came from ripened ovaries. They are the sclerified inner layer of tiny, ovule-bearing ovaries after the thin, fleshy, outer pericarp layer has been removed. Hollow (seedless) drupelets produced without pollination and fertilization are called cenocarps. If the inner layer of drupelets contain fig wasps they are called psenocarps. These come from short-style female ovaries inside caprifig syconia where female Blastophaga psenes inserted her ovipositor to lay her eggs. As I have stated many times on Wayne's Word, the fig & its symbiotic wasp is truly one of the most complicated interactions of a plant and an insect on this planet! That is why I posted the following Trivia Note on Facebook:
Wayne's "Remember When" #70 (1 June 2021)

I have communicated with many prestigious naturalists during my career at Palomar College, but one of the most famous was Richard Dawkins of Oxford University regarding the fig & its symbiotic pollinator wasp. This is truly one of the most complex & fascinating relationships between a plant & an insect. See Wayne's Complete Facebook Index

Left: Caprifig with developing mammoni crop of syconia. Right: F. carica cultivar 'Calimyrna' with developing 2nd or main crop of syconia. Both of these syconia form in early summer on new growth. They mature in late summer to early fall. The immature Calimyrna main crop is pollinated (caprified) in June by wasps carrying pollen from the previous profichi crop of caprifigs. Without caprification this main crop will drop from the tree, a trait known as caducous. The mature mammoni syconia will release another generation of female fig wasps who will enter the 3rd or mamme crop of caprifigs in the fall. This crop will overwinter on the tree when all the leaves have fallen.

8. Time Lapse Between Caprifig Crops & Wasp Survival

Caprifig (male trees) generally produce 3 syconium crops per year: the summer "profichi" crop (with wasp-bearing "gall" flowers & pollen-bearing male flowers); an autumn "mammoni" crop (wasp-bearing & abortive male flowers); and an overwintering "mamme" crop (wasp-bearing & abortive male flowers). The mammoni crop is sometimes late or doesn't develop and is replaced by overwintering mamme crop.

If the 3 crops of caprifigs overlap each other in the proper sequence (i.e. are in sync.) the female fig wasps can move from the profichi to mammoni and to overwintering mamme crops; however, if any crop should fail, it would be fatal to the wasps living in the protective figs unless they had figs on other trees in which to breed. If there is a considerable time lapse between profichi, mammoni and mamme crops, then another caprification will be necessary, possibly from another caprifig or different caprifig variety. According to fig authority Dr. Gustav Eisen (1901b), different caprifig varieties have one, two or three crops of syconia: uniferi, biferi, & triferi. He recommends growing several different caprifig varieties in fig orchards.

As of 4 July 2020 I noticed a time lapse between profichi and receptive mammoni crops in my 'Vista Caprifig' in Twin Oaks Valley, northern San Diego County. The profichi crop was dried up and there were no female Blastophaga wasps inside the syconia. I assumed they all exited. The mammoni crop were just appearing as small, hard syconia that were not yet penetrated by female wasps. The mammoni crop appeared to be out of sync. with exiting wasps from profichi crop. According to Ali Sarkhosh, et al. (The Fig: Botany, Production & Uses, 2022), the receptive stage of mammoni coincides with the donor stage of profichi; however, the production of mammoni syconia may be irregular. In fact, the mammoni crop may not develop and wasps may lay their eggs in the receptive mamme crop one or 2 months later. Can female Blastophaga wasps survive outside their profichi syconia to lay their eggs in a delayed mammoni or mamme crop when they are receptive?

For a dioecious species like Ficus carica, it would be normal and advantageous for wasps exiting the profichi crop to pollinate female trees for seed production and perpetuation of the species in its natural habitat. Therefore, a time lapse between profichi and receptive mammoni crops may be beneficial to the species.

On 23 July 2020 I examined a developing mammoni syconium on my 'Vista Caprifig' and to my surprise discovered the presence of several dead female Blastophaga wasps in the ostiole region and in the interior. So even though the mammoni crop appeared to be late, this syconium was still penetrated by ovipositing wasps. Wasp larvae were also present in ovaries of short-style female flowers within mammoni syconia examined 26 Aug 2020. The following image of a mammoni syconium was taken 1 Sept 2020. It contains many wasp-bearing ovaries (psenocarps). So it looks like even though the initial mammoni crop appeared out of sync. with exiting wasps from profichi crop, at least some mammoni syconia received ovipositing wasps and developed a new generation of wasps for the fall mamme crop.

'Vista Caprifig'

In early June 2022, when my 'Vista Caprifig' profichi crop was shedding pollen & releasing female Blastophaga wasps, receptive mammoni syconia were not visible (or very minute) on the new 2022 growth (see following image). I have not observed another mature, syconia-bearing caprifig in my immediate neighborhood; however, I do have nearby female trees ('Calimyrna' & 'Verte') that do get pollinated. This would explain the fig seedlings that appear in my yard. In 2020, the developing, receptive mammoni crop did not appear until later in June. I plan to document & photograph the 1st receptive mammoni to appear on this tree in 2022 (see below). My question is: Where do these newly released female wasps go during the interim before receptive mammoni syconia develop? Some obviously go to my nearby female trees ('Calimyrna' & 'Verte'). Are there late-maturing profichi that supply wasps to the receptive mammoni crop later in June?

Caprifig Profichi Crop Releasing Pollen-Bearing Female Wasps In Early June 2022

'Vista Caprifig'

'Vista Caprifig'

According to Kjellberg et al. (1988), female fig wasps from mature profichi syconia may survive until receptive mammoni or mamme syconia are available. "Interestingly, on the island of Zia (Greece), the wasps were thought to spend some time on the local thistle, Scolymus hispanicus. Present-day inhabitants of the Kerkennah Islands in Tunisia never cultivate the land beneath male F. carica trees, possibly in the belief that fig wasps can subsist there on nectar-rich plants."

Caprifig Profichi Crop At Palomar College Releasing Pollen-Bearing Female Wasps
Minute Syconia In Leaf Axils When Profichi Crop Was Releasing Wasps (8 June 2022)

'Vista Caprifig'

On 10 June 2022 I found one receptive syconium on the 2022 growth of my Twin Oaks Valley 'Vista Caprifig'. I am reasonably certain it was a mammoni syconium because the profichi crop on an older 2021 branch had already shed wasps and was wilted. In addition, the profichi crop was initiated the previous fall of 2021. Numerous wasps from the profichi crop covered the receptive mammoni. At this time most of the syconia in leaf axils were very small and not receptive. Whether all of these minute syconia will develop into mature mammonii by August is unknown at this time. I am not even certain they are mammoni or mamme.

Unfortunately, many of the wasps were carried away by Argentine ants (Linepthema humile) before they entered the ostiole to lay their eggs. To alleviate the Argentine ant attacks, I placed Terro®: ant bait under the tree. This is a borax + sugar solution (lethal to ants) that worker ants take back to their nests. Blastophaga wings protruding from the ostiole is clear evidence that one or more wasps have penetrated the syconium.

8A. 2022 Mammoni Syconium & Female Blastophaga Wasps

'Vista Caprifig'

Following Image Shows A Mammoni Syconium On 2022 Stem:

'Vista Caprifig'

8B. Parthenocarpic 'Vista Caprifig' Mammoni Syconia With Hollow Cenocarps

Photographed 2 August & 4 August 2022

My 'Vista Caprifig' during early August 2022 produced unpollinated, parthenocarpic mammoni syconia containing hollow drupelets (cenocarps). It also produced mammoni syconia containing wasp-bearing drupelets (psenocarps)--see following image. These female wasps will hopefully enter the receptive mamme crop in fall and overwinter on the tree.

8C. 'Vista Caprifig' Mammoni With Wasp-Bearing Psenocarps & Pollen

Photographed 16 August 2022: Including Blastophaga Orgy

Photographed 18 August 2022: Including Pollen From Mammoni Syconium

Proof that male flowers in caprifig mammoni syconia do indeed produce pollen. Pollen grains of Ficus carica are typically 2-porate (diporate) with 2 pores through the protective, decay-resistant exine layer. [mono & tri-porate pollen has also been reported in caprifigs.] The exine coating of plant spores and pollen grains is composed of a durable biopolymer called sporopollenin. Although it contains only carbon, hydrogen and oxygen, it is different from carbohydrate polymers such as starch & cellulose. It is one of the most stable organic compounds known. It has been extracted from plant spores using strong acid and alkali solutions that would disintegrate other substances. In fact, spores & pollen are well preserved in soils and sediments.

8D. 'Vista Caprifig' Mammoni Syconia With Seed-Bearing Endocarps

Note: When mammoni syconia have been pollinated by fig wasps from profichi crop, the drupelet may contain a seed if the wasp did not oviposit inside the ovary of drupelet. As stated above, drupelets are the individual fruits (ripened ovaries) within the syconium. They resemble miniature drupes surrounded by an ovary wall (pericarp) with a sclerified endocarp layer. The seed coat develops from the outer layer (integuments) of ovule within the ovary. In drupelets containing a seed, the seed coat and endocarp layers are close together. If seed-bearing endocarps sink in water they are probably viable. I have extracted up to 10 presumably viable endocarps from one syconium (see right panel of following image). For more details see I.J. Condit "The Structure and Development of Flowers in Ficus carica L." (Hilgardia, 1932).

Since figs are protogynous, with female flowers receptive before male flowers shed pollen, cross pollination between different plants is generally favored. This is especially true in dioecious (gynodioecious) figs, such as Ficus carica with male (caprifig) and female trees. Seed production in caprifig mammoni syconia results from self pollination (selfing) because both gametes came from same caprifig parent and are genetically identical. Protogyny is probably not a issue because the gametes come from different syconia at different times on caprifig branches (profichi & mammoni). This may be an example of "geitonogamy" [guy-ton-OG-uh-mee], self pollination between different flowers on the same plant with genetically identical gametes. Self pollination within the same flower is autogamy and the genetic result is the same as geitonogamy. Plants have evolved many adaptations to avoid the deleterious effects of inbreeding, known as inbreeding depression.

According to Hossaert-McKey & Bronstein (American Journal of Botany Vol. 88, 2001), selfing occurs in the tropical, monoecious fig Ficus aurea without negative effects of inbreeding. In fact, no negative effects of selfing could be demonstrated on syconium retention, number of vacant ovaries, seed set, or seed germination; however, wasp production had a tendency to be higher after self-pollination. Dioecy (populations with separate male & female individuals) favors cross pollination and is considered evolutionarily advanced in figs compared with ancestral monoecious species.

8E. 'Vista Caprifig" & Wasp Exodus From Purple Mammoni 31 Aug. 2022

During the summer of 2022 I carefully watched the developing syconia on my 'Vista Caprifig' following the exodus of wasps from the profichi crop. Several crops of wasp-bearing syconia developed on the branches after the profichi crop withered. Upon maturation these changed from green to purple. I assumed these were mammoni because they followed the profichi crop; however, there were several crops prior to the overwintering mamme crop in fall and the initiation of profichi buds that will develop on the next year's stem growth. The following image (taken 31 August) shows a mature purple syconium with exiting wasps entering 2 smaller green mammoni syconia. Most fig references state that syconia developing after the profichi crop and ripening before winter are called mammoni. On my caprifig these syconia were produced throughout the summer of 2022. None of these marked with colored string became overwintering, wasp-bearing mamme.

Production Of Mammoni Syconia Throughout Summer Months

During summer 2022, I carefully observed the 'Vista Caprifig' at my home in Twin Oaks Valley, San Marcos. Mammoni syconia were produced throughout the summer months, not just in June when the mature profichi crop was releasing Blastophaga female wasps & pollen. In fact, some of the mammoni syconia contained wasp-bearing psenocarps, some contained hollow cenocarps, and some contained seed-bearing endocarps. In addition, some syconia contained pollen-bearing male flowers. The following image of 2 syconia was taken on a rainy day in October. The syconia were marked with red string in August. They ripened into purple, mature syconia that withered by November. They did not become overwintering mamme.

Following image shows one of the above mammoni syconia in November.
It was infested with numerous larvae of dried fruit beetle (Carpophilus).

This is probably an overwintering, wasp-bearing, mamme syconium.
I will verify in a few weeks when caprifig has dropped its leaves.

8F. Young Profichi In February 2023: Produced On 2022 Wood

This image shows that all three crops of syconia, including mammoni, mamme & profichi, are all produced on same branch in same year (e.g. 2022); however, the profichi crop mature in late spring of following year (e.g. 2023). In fact, the pollen-laden wasps from mature profichi crop are used to pollinate receptive syconia on female 'Calimyrna trees' in June. They also enter receptive mammoni syconia on the caprifig that perpetuates the cycle of fig wasps into mamme & profichi syconia for following year. Contrary to some fig references, the mammoni syconia on my 'Vista Caprifig' produce pollen and even some seeds in ovaries not inhabited by fig wasps (see section American Journal of Botany Vol. 88, No. 4 (Apr., 2001) above).

The small profichi buds that appear in the fall are referred to as "arrested buds" because they don't develop into mature, wasp-bearing & pollen-bearing profichi syconia until the following late spring. The overwintering, larvae-bearing, mamme syconia do not release adult winged female wasps until spring, coinciding with receptive profichi syconia. Timing is crucial for these wasps to enter the receptive profichii. Variations in this pollination cycle also occur in about 900 additional monoecious & dioecious fig species on our planet, each with one or more unique symbiotic fig wasps. This is why I categorically say that the fig & fig wasp scenario is the most complex interaction between a plant and an insect on Earth!

  Details Of Mamme & Profichi Crop Under #18 Above  

9. Ficus carica With Persistent vs. Caducous (Early Deciduous) Syconia

According to W.B. Storey (1975), there is a dominant mutant allele (P) for persistent syconia and ovule abortion. This allele is egg lethal so it can only be carried in the sperm. In other words, it cannot be passed on from a persistent female tree. The homozygous genotype PP is not possible. A recessive wild type allele (+) results in caducous syconia and normal ovule development. It can be carried by the egg and sperm. Therefore the only possible genotypes for caprifigs and female trees are P+ and ++. Persistent caprifigs and persistent female trees must be heterozygous (P+). Mature pollinated syconia on heterozygous female trees having the allele for persistence (P) may contain hollow drupelets (cenocarps) as well as normal seed-bearing drupelets. Although I don't have a specific reference, I don't see why the persistent allele (P) could not occur in wild populations of F. carica. This allele does not appear advantageous to the female fig, although if wasp-bearing caprifigs are nearby the syconia are capable of producing seeds.

The explanation (hypothesis) for a dominant, persistent, egg lethal allele explains some genetic ratios in figs: "Lethality of the P allele to ovules receiving it enforces heterozygosity on all trees with persistent syconia and precludes the probability of homozygosity in seedling progenies regardless of whether the persistent phenotype serves as a seed parent or as a pollen parent. This accounts for the deviation from the 3:1 ratio which one ordinarily expects from the mating of monogenic genotypically identical heterozygotes. It accounts, also, for the failure of the persistent phenotype to appear when the flowers of a tree of the persistent phenotype are pollinated with pollen from a tree of the caducous phenotype." [The Fig by W.B. Storey, J.E. Enderud, W.F. Saleeb, and E.M. Nauer. 1977.]

'Verte' breba crop photographed 9 May 2021 at my home in Twin Oaks Valley, San Diego County. The small buds of main (2nd) crop are visible in leaf axils of new (2021) growth. The breba crop are on the previous year's (2020) stems. These "almost mature" breba are unpollinated and persistent. The main crop will be ripe in late summer. Although parthenocarpic, this 'verte' main crop is typically pollinated by Blastophaga from pollen-bearing profichi crop on nearby 'Vista Caprifig'. The inset image was photographed the next day 10 May 2021. The single dead Blastophaga psenes was crammed into the ostiole of 'Verte' breba syconium. It did not pollinate any flowers in the breba syconium. This female wasp undoubtedly came from the overwintering mamme crop on the nearby 'Vista Caprifig'.

This is a complicated subject when discussing the biology of Ficus carica. In general, unpollinated parthenocarpic cultivars with the persistent gene must be propagated by cuttings because the drupelets in their syconia are hollow cenocarps without seeds. These cultivars have been grown and selected for flavorful "figs" and, like many other excellent fruit cultivars, must be propagated asexually in order to obtain clones. Cultivars such as the 'Verte' are valuable because they are absolutely delicious and do not require wasp pollination in order to set fruit. If these parthenocarpic cultivars are pollinated by a nearby caprifig they can produce seed-bearing drupelets in addition to hollow drupelets (cenocarps). The remains of female F. carica syconia have been discovered in archaeological sites of the Jordon Valley that date back 11,400 years. They are clearly persistent, parthenocarpic syconia containing hollow drupelets (cenocarps). When M.E. Kislev concluded they were planted by cuttings and possibly represented the first known domesticated plants, perhaps he assumed that the trait for persistent syconia was unique to seedless fig cultivars. According to Storey (1975), this gene can occur in both female trees and caprifigs. It is passed to female progeny in the sperm of caprifig pollen parents. Female parthenocarpic trees with the persistent gene can produce seeds if they are pollinated by fig wasps. The ancient syconia of the Jordon Valley with hollow cenocarps could have come from unpollinated female trees that grew from seeds.

  See Section On Early Domestication Of Ficus carica In The Jordan Valley  

P = Dominant allele for persistent syconia & ovule abortion (egg lethal). Mutant allele Acc. to Storey (1975)
+ = Recessive allele for caducous syconia & normal ovule development.  Wild Allele Acc. To Storey (1975)

Genetics of Persistent Vs. Caducous Alleles in Ficus carica.

Following table based on Storey, W.B. 1975. "Figs." In: Advances in Fruit Breeding, Purdue Univ. Press, 1975, pp. 568-589. Originally from
Saleeb, W.F. 1965. "Genetics and Cytology of Syconium Persistence in Ficus carica." Ph.D. Dissertation, Univ. of California, Riverside.

Female Fig
All ++
+ (P dies)
All ++
P and +
1 P+: 1 ++
+ (P dies)
P and +
1 P+: 1++

Cross Between Persistent Female Tree (P+) and Persistent Caprifig (P+):

Alleles in Eggs Of Seed Parent
P is "Egg Lethal" & Cannot Be in Egg
PP Progeny Not Possible
Alleles In Sperm Of Caprifig Pollen Parent

Cross Between Persistent Female Tree (P+) and Caducous Caprifig (++):

Alleles in Eggs Of Seed Parent
P is "Egg Lethal" & Cannot Be in Egg
Heterozygous P+ Progeny Not Possible
Alleles In Sperm Of Caprifig Pollen Parent

Cross Between Caducous Female Tree (++) and Persistent Caprifig (P+):

Alleles in Eggs Of Seed Parent
Heterozygous P+ Progeny Possible
Because P Allele Carried By Sperm
Alleles In Sperm Of Caprifig Pollen Parent

Above tables based on Storey, W.B. 1975. "Figs." In: Advances in Fruit Breeding, Purdue Univ. Press, 1975, pp. 568-589. Originally from
Saleeb, W.F. 1965. "Genetics and Cytology of Syconium Persistence in Ficus carica." Ph.D. Dissertation, Univ. of California, Riverside.

Note: In fig crosses where you would like the persistent gene (P) in your offspring, the pollen parent must be a persistent, heterozygous caprifig (P+). The persistent gene (P) cannot come from female parent even if it is persistent; therefore, the persistent caprifig cannot be homozygous (PP). Persistent caprifigs have been used in crosses to develop a possible persistent Calimyrna with quality syconia that don't require caprification. What I don't understand here is that pollinator wasps are responsible for fruit set and viable seeds in caducous Calimyrna figs which impart a superior nutty flavor to these delicious figs. Persistent figs are seedless without pollination unless there is a caprifig with fig wasps nearby.

According to Neeman and Galil (1978), caprifigs can produce seeds if the ovaries of short-style female flowers within the syconium are pollinated by fig wasps, but not inhabited by wasp larvae. The seed-bearing endocarps will sink in water. A true heterozygous, persistent caprifig that has never been caprified (pollinated) by fig wasps would not produce viable seeds that sink in water.

G. Neeman & J. Galil. 1978. "Seed Set in the 'Male Syconia' of the Common Fig Ficus carica L. (Caprificus)." New Phytol. 81: 375-380.

Ripe Calimyrna figs grown in San Diego County. Minute pollinator wasps are responsible
for fruit set and crunchy seeds which impart a superior nutty flavor to these delicious figs.

10. Other Explanations For Persistent Vs. Caducous Syconia (Transcriptomic Analysis)
The following is from Storey, Enderud, Saleeb & Nauer (1977): "Caducous syconia remain on the tree and develop to maturity if stimulated to do so. It occurs naturally, of course, when caprifigs are colonized and figs are caprified or hand pollinated. It may be induced by blowing air into the syconium, by an invasion of mites or insects, by mechanical injury, by closing the ostiole with a drop of a viscous vegetable oil, or by treating with plant growth regulators. Dropping may also be inhibited by cool weather which inhibits differentiation of an abscission zone in the peduncle."

San Pedro-type cultivars of Ficus carica produce a good, persistent breba crop; however, the main (2nd) crop is caducous and typically needs caprification for fruit setting and development. Condit (Fig Varieties: A Monograph, 1955) also sites the San Pedro cutivar 'King' with persistent, uncaprified syconia as well as caprified, seed-bearing syconia. Condit states that without caprification the 'King' drops practically all of the main crop at Riverside, but "matures a large percentage in coastal climates." There are many "common figs" that almost always drop their breba crop, while other common varieties retain them. I have a volunteer fig grown from seed in which some breba drop and some are retained! As stated above by Condit (1955), there may also be climatic (weather) factors involved in the persistency or dropping of syconia.

Even as early as 1968, plant physiologists recognized that auxins and gibberellin-like substances were involved in the formation of parthenocarpic and nonparthenocarpic syconia of the San Pedro cultivar 'King'.

Farooq Lodhi, Muriel V. Bradley, and Julian C. Crane. 1969. "Auxins and Gibberellin-like Substances in Parthenocarpic and Non-parthenocarpic Syconia of Ficus carica L., CV. King." Plant Physiol. 44: 555-561.

The mechanism underlying two crops with differential parthenocarpy in San Pedro-type figs (i.e. parthenocarpic breba and non-parthenocarpic main crop) has been largely unknown. It appears to be more complicated than a single, dominant egg-lethal allele (P) for persistent syconium. Transcriptome analysis of San Pedro-type Ficus carica by Lijuan Chai, et al. (Tree Genetics & Genomes, Vol. 13, 2017) reveals divergent phytohormone-related gene expression. Transcriptome analysis involves the complete set of RNA-transcripts produced by the genome, including coding and non-coding RNA. It has been particularly useful in identifying the functions of genes, including gene expression studies in botany and medicine. The results of Lijuan Chai, et al. study suggest that divergence of the parthenocarpic fates of breba and main crop of San Pedro-type fig occurs at very early stages of syconia development where auxin may play a major role, in the absence of pollination. In addition, main crop abscission at the end of phase I (phase of rapid growth in size) was modulated by differentially expressed phytohormone metabolism and signaling pathways. This topic is way beyond the scope of the Wayne's Word fig biology page; however, I have included several references, one of which is available on-line.

Chai, Lijuan, Wang, Ziran, Chai, Peng, Chen, Shangwu, & Huiqin Ma. 2017. "Transcriptome Analysis of San Pedro-Type Fig (Ficus carica L.) Parthenocarpic Breba and Non-Parthenocarpic Main Crop Reveals Divergent Phytohormone-Related Gene Expression." Tree Genetics and Genomes Volume 13, Article number: 83. (2017).

Chai, L., Chai, P., Chen, S. et al. 2018. "Transcriptome Analysis Unravels Spatiotemporal Modulation of Phytohormone-Pathway Expression Underlying Gibberellin-Induced Parthenocarpic Fruit Set in San Pedro-Type Fig (Ficus carica L.)." BMC Plant Biol 18, 100 (2018). Available On-Line.

Chai, Peng, Dong, Sujuan, Chai, Lijuan, Chen, Shangwu, Flaishman, Moshe, & Huiqin Ma. 2019. "Cytokinin-Induced Parthenocarpy of San Pedro Type Fig (Ficus carica L.) Main Crop: Explained by Phytohormone Assay and Transcriptomic Network Comparison." Plant Molecular Biology Volume 99, Pages 329–346. (2019).

Transcriptomic analysis also indicates that ancestral monoecious Ficus carica varieties with breba and main crops evolved into a dioecious species with "female" trees and "male" caprifigs. This remarkable discovery comes from genes involved in flowering, fruit development and ripening, differentially expressed in the breba and main crop. The male (caprifig) can have three crops similar to the female fig: (1) the profichi in spring-beginning summer; (2) the mammoni in summer-autumn; and (3) the mamme during autumn-winter. Either the presence or the amount of the three crops may vary consistently among varieties of caprifig. The male flowers for the caprification of the main crop in the edible fig are present in the profichi of the caprifig. Female flowers are either short-styled or long-styled, with the first type located in the syconia of the caprifig and the second type in the syconia of the edible fig. All these flowers are inserted on a receptacle forming the syconium. This “difference” of crops lead to the distinction of the varieties in uniferous (only one crop, main crop), biferous (two crops, breba, and main), and even triferous (breba, summer, and late main crop). The crops on female trees are very similar in appearance to caprifigs, and is the explanation behind "vicarious selection" discussed later on this page. According to Yogev Rosianski, et al., 2016 (Sci. Hortic.198, 98–106), pollinated ripe fig fruits are much better than parthenocarpic fruits in growth, width, weight, firmness and taste qualities. In my experience with common figs and the 'Vista Caprifig' on my property, I would certainly agree with the previous statement.

Marcotuli, Iluria, et al. 2020. "Fruit Development in Ficus carica L.: Morphological and Genetic Approaches to Fig Buds for an Evolution From Monoecy Toward Dioecy." Frontiers in Plant Science Volume 11, Article 1208 (14 pages). Available On-Line.

Morphological and genetic analysis also indicates a possible distinction of two horticultural types of "female" Ficus carica (syconia with long-style female flowers) instead of three types: The Common type that does not strictly require pollination (persistent type) and the SanPedro type strictly requiring pollination to set fruit (caducous type). Phylogenetic analysis of the 24 fig genotypes revealed a clear distinction between Common and San Pedro type figs. The Smyrna type should be included in the latter category. A third type would include "male" Caprifig cultivars (syconia with male flowers and short-style female flowers). Caprifigs were considered a fourth type in the traditional 4 category system described by Storey, Enderud, Saleeb and Nauer (1977).

Ferrara, Giuseppe, et al. 2016. "Characterization of Edible Fig Germplasm From Puglia, Southeastern Italy: Is The Distinction of Three Fig Types (Smyrna, San Pedro and Common) Still Valid?" Scientia Horticulturae Volume 205, Pages 52-58. Available On-Line

11. Pollinated Parthenocarpic Figs At Wayne's Word

Seed-bearing endocarps of Ficus carica variety 'Verte' at the bottom of a dish of water. Although this cultivar is parthenocarpic, it has been pollinated by fig wasps from a nearby caprifig. Endocarps with mature, viable seeds typically sink in water. These are the actual fruits of a fig. They are the sclerified inner layer of tiny, ovule-bearing ovaries after the thin, fleshy, outer pericarp layer has been removed. Hollow (seedless) drupelets produced without pollination and fertilization are called cenocarps. If the endocarps contain wasp larvae they are called psenocarps.

Wayne's Word has a large 'Vista Caprifig' and an abundant supply of male and female fig wasps (Blastophaga psenes). For this reason, parthenocarpic figs like var. 'Verte' get pollinated even though the syconia will ripen without fig wasps and contain hollow endocarps without seeds called cenocarps. The main (2nd) crop of parthenocarpic figs at Wayne's Word produce syconia loaded with seed-bearing endocarps because of all the resident winged female fig wasps from profichi crop of nearby caprifig. This explains all the male and female seedling figs ('Verte' offspring) that come up throughout the property and possibly elsewhere in the neighborhood.

This image of syconium from main (2nd) crop of 'Verte' offspring was taken in late summer 2020. Obviously it was pollinated by Blastophaga psenes from profichi crop of nearby 'Vista Caprifig'.

This image of a syconium from breba crop of 'Verte' fig was taken in early July 2021. Like the above image, it is loaded with endocarps (sclerified inner layer of drupelets); however, there are no seeds. The receptive breba crop was too early for release of pollen-bearing Blastophaga wasps from profichi crop on nearby caprifig. Therefore, the endocarps (called cenocarps) are hollow and do not contain mature seeds. Unlike seed-bearing endocarps that sink in water, these cenocarps float in water.

Another view of 'Verte' offspring taken 30 April 2021 showing the breba crop. At this time I am uncertain if any breba syconia will remain on the tree. It is not likely that wasps from mamme crop of nearby caprifig would carry pollen.

12. Hunting For Wild Seedling Figs In California

Smithsonian (March 2022) contains an article about hunting for "wild figs" in California to find superior "varieties." Apparently this has become a competitive endeavor by "fig-hunters" in CA. Wild figs are Ficus carica trees that grew from viable seeds in rural areas. Obviously the seeds came from syconia on parental female trees pollinated by male caprifigs. The only way to get "wild" Ficus carica (i.e. from viable seeds) is pollination of female parental tree by fig wasps from nearby male caprifigs (like the one in my yard). The wasps seek out female (fruit-bearing) trees with tiny receptive syconia that enlarge & ripen. If pollinated, the mature syconium will contain viable seeds. Randomly searching for the best tasting wild female tree is essentially "selection" and is highly subjective. I suppose you might get a genetic reshuffling that is superior to the known 500+ named varieties. I wonder if the female parent of a so-called "new discovery" originated from one of these original cultivars. Dr. Condit at UC Riverside spent an entire lifetime on this endeavor. In fact, selection goes back thousands of years. Another professor, Dr. Storey, wrote many articles and a book about this subject and the genetics of Ficus carica. Many years ago my fig-grower friend, Steve Disparti, and I met Dr. Storey at his home in Riverside. According to an ecologist mentioned in the Smithsonian article, wild figs are very invasive, especially in riparian habitats.

Generally, the genetic resuffling in seedling fruit trees is undesirable. That is why choice fruit trees are grafted to rootstock. This is also why choice fig cultivars are propagated by cuttings. An exception might be to introduce wild genes into long-cultivated species that have lost important genes through selection over many generations.

I have seedling figs in my yard, one of which is quite tasty--although I think its mother fig (var. 'verte') is superior. My 'Vista Caprifig' has fathered many offspring, including fig seedlings that came up in my neighbor's yard. Birds love figs and transport the seeds in their droppings. BTW, seedling figs can be male (caprifig) or female. The only reliable (easy) way to tell male from female is to open a ripe syconium and see if it contains pollen (& fig wasps).

I have many questions about the "fig-hunting" craze.

1. What are the odds of finding a seedling tree that is superior in flavor to cultivated varieties. One of the seedling trees in my yard has a good-tasting syconium, but not as delicious as its 'Verte' female parent. The caprifigs in CA also contribute genes to the newly discovered "wild fig" genomes.

2. Are the "fig-hunters" aware of all the hundreds of superior (flavorful) Ficus carica varieties described by Condit & Storey.

3. Fig biology and cultivation is very complicated. Fig growers in CA fig orchards must take precautions against internal rot fungus (endosepsis) transmitted by fig wasps to syconia on female trees. Another potential issue with fig propagation in some areas of California is root-knot nematodes in the soil.

Original Posts On Forum:

Posted by Foodtreefield: "Yes figs are growing wild there and many other areas in California. So much so that it is listed as an invasive non-native species by some counties. Chances of finding a superior new fig are indeed small but maybe a bit better odds than the lottery because many of the wild trees are direct descendants of cultivated trees. In my area they are plentiful in the flood channels and could help choke water flow contributing to flood events. And virtually all of them are inedible."

Posted by Bluemalibu: "Two thoughts instantly come to mind... First, except for the few purposely-bred varieties that we are currently cultivating, remember that every other cultivar was once a wild fig. So, there have been over 3,000 wild figs [that] have been thought by someone as to rate high enough as to be worthy of attaching a name to it, and to cultivate it.

"And secondly, in my experience, I have found that I will usually go through well over a hundred wild trees, before I find a tree [bearing] figs that I think would be worth the time and the effort needed to propagate copies of it. So, let's say our chances are maybe one in a hundred, vs. one chance in millions on the lottery. But, those diamonds are indeed out there... as a case in point, we trialed somewhere around 60 varieties of figs at the two get-togethers held here in California over the last three weeks. And at both of these events, an unassuming wild fig, the Meteorito, was judged by most in attendance to be one of the top figs for taste. So, you just never know..."

Article About California Fig Hunters In Sacramento News & Review

Alastair Bland, another fig-lover, wrote the following article entitled "Fig Collectors’ Paradise" for Sacramento News & Review (April 28, 2021): "I was, and remain, quite obsessed with figs—and it turns out I’m not alone. Across the nation, and the world, a community of fig-crazed gardeners has emerged in recent years. Doug Scofield, of Thermalito, is one of these fanatics. Almost anytime he drives someplace, he eyes the vegetation beside the road, looking for the distinctive foliage, scattered shades of green, large leaves and sweeping branches of a fig tree. While kayaking, too, he scans the riverbanks.

"Scofield guesses that just one wild fig in a thousand will produce fruit worth noting on social media, but he has found several. A few years ago, he came across a wild fig tree laden with plump green fruits with jammy, berry-red pulp inside. He named it Thermalito, and it has since become a collector’s item. More recently, Scofield found a fig that he swears is the best fruit he has ever tasted. He named the fig Angelito.

13. The Ficus pseudocarica - F. palmata Controversy

'Vista Caprifig' Discussed In Following Paragraphs

Note: The rooted shoot from wild seedling caprifig that I transplanted from a roadside creek in Vista, California is a noteworthy hybrid discussed in the following paragraphs. In my opinion it is different from typical F. carica, and keys out fairly close to F. pseudocarica in Condit's classic books The Fig (1947) and Ficus: The Exotic Species (1969). It also appears slightly different from original F. pseudocarica discussed in the literature. I have propagated clonal cuttings to several fig growers in California and the campus of Palomar College. In order to distinguish this very productive clone, I will continue to refer to it as 'Vista Caprifig' .

'Vista Caprifig'

According to Ira Condit's monograph on fig varieties (1955), the caprifig of this species has a distinctive profichi syconium that is purple-black in color with a "sender neck and long, slender stalk." My 'Vista Caprifig' profichi crop generally have a long, slender neck but a short stalk (peduncle). In his classic volume The Fig (1947), Condit describes the syconium as smaller than other varieties of F. carica. In Ficus: The Exotic Species (1969), Condit describes the twigs of F. pseudocarica as velvety pubescent and the twigs of F. carica as glabrous or only slightly puberulent when young. F. pseudocarica is listed as a synonym of F. palmata (Punjab fig) in the Kew List Of Plant Species (2011). It is listed as naturalized in California (under F. palmata) in the Calflora Database and USDA Plant Database. According to the revised Jepson Manual (2011), reports of F. pseudocarica and F. palmata are based on misidentified specimens of F. carica (A.T. Whittemore, 2006, Sida 22: 769-775).

According to Condit (1955), Ficus pseudocarica is native to Eritrea and Abyssinia, while F. palmata is indigenous to Pakistan, northern India and Afghanistan. He states that F. pseudocarica was introduced into Santa Barbara, California in 1902, and like F. palmata, was used for hybridizing with F. carica. In fact, the edible 'Brawley' caprifig cultivar is a hybrid between F. carica var. 'kadota' and a F. pseudocarica caprifig (Storey et al. 1977). Ficus palmata is commonly used in modern floras, with F. pseudocarica listed as a synonym. Alan Whittemore (2006) has studied herbarium collections of F. palmata (F. pseudocarica) from California and has concluded that they are misidentified and should be labeled F. carica. He compared 4 collections of "F. palmata" by H.M. Pollard from Cold Spring Canyon, Santa Barbara Co. during the 1950s with 31 sheets of F. palmata from India, Nepal, Pakistan, Saudi Arabia, Yemen, Eritrea and Ethiopia and 70 sheets of cultivated F. carica worldwide. [Interestingly enough, Pollard's 1950 collections at Rancho Santa Ana Botanic Garden are labeled F. pseudocarica.] Whittemore used 14 characteristics in his analysis of Pollard's sheets, 10 of which matched F. carica better than F. palmata. According to Whittemore, F. palmata (F. pseudocarica) was occasionally grown horticulturally in California, but there is no evidence that it ever escaped from cultivation.

Mallikarjuna Aradhya et al. (2010) studied 194 fig accessions maintained at the USDA National Clonal Germplasm Repository, Davis, California. Their extensive DNA cladogram shows F. pseudocarica on a sister clade with the 'Hacin' cultivar of F. carica, between clades of the popular F. carica cultivars 'Zidi' and 'Roeding.' All of these varieties were derived from the ancestral F. pumila. Under "Materials and Methods," Aradhya et al. cite the single accession of F. pseudocarica as a synonym of F. palmata. Dna cladograms by Nina Rønsted et al. (2005 and 2006) show F. palmata in a clade far away from F. pumila and certainly not derived from F. pumila. In another cladogram by Rønsted et al. (2008), Ficus pumila (Subsection Frutescentiae) is placed close to F. palmata (Subsection Ficus). In the latter cladogram, the sister clade of F. palmata is F. johannis, another closely-related deciduous fig in the Ficus carica-F. palmata complex. F. pumila has been artificially crossed with F. carica, indicating a close genetic relationship. It is unfortunate that F. carica was not included (at least by name) in these phylogenetic trees; however, the authors considered F. johannis synonymous with F. carica. Therefore, F. carica would be on sister clade with F. palmata!

On 8 Jan 2022 I checked the Kew Plants of the World Online and they listed Ficus pseudocarica Miq. as a synonym of F. palmata ssp. virgata Browicz. (Kew: Ficus pseudocarica). In my humble opinion, their included images do not exactly match the 'Vista Caprifig' in my yard. It is interesting to note that on 8 Jan 2022 The International Plant Names Index (IPNI) listed this species as F. psdeudocarica Miq. without an infraspecific rank. (IPNI: Ficus pseudocarica).

Because of the contradictory statements in above paragraphs, I will refer to the male fig in my yard as 'Vista Caprifig'. In biological naming conventions, cf. is commonly placed between the genus name and the species name (specific epithet) to describe a specimen that is difficult to identify; in other words, the actual species-level identification cannot be certain; however, due to the complexity of this taxonomy, I will just use 'Vista Caprifig' for the clone in my yard.

As I stated above, the extensive DNA cladogram of 194 accessions by Mallikarjuna Aradhya et al. (2010) shows F. pseudocarica on a sister clade with the 'Hacin' cultivar of F. carica, between clades of the popular F. carica cultivars 'Zidi' and 'Roeding.' Based on this data, it certainly appears closely related to F. carica, possibly a var. of that species complex. The marvelous 'Vista Caprifig' in my yard was rescued from a roadside creek in Vista, CA and resembles Ficus pseudocarica at test plots at UC Riverside in June 1985.

According to Aradhya et al. (2010), deciphering genetic identity and relationships among all these these cultivars is complicated due to occurrence of extensive synonymy and non availability of authentic source cultivars for comparison. The genetic and geographic origin of most of these cultivars is unknown and associated passport data are incomplete, inaccurate, or missing in most germplasm collections. According to Richard Frost (Plos One 7 Feb. 2022), some genetic (SSR) profiles from the National Clonal Germplasm Repository, Davis, CA, for Ficus carica & F. palmata are incorrect, particularly analysis of genetic distances.

Overall, the classification of fig cultivars is largely based on skin and pulp color, floral biology, pollination behavior and parthenocarpy, which are probably governed by simple Mendelian genes and may be unrelated to molecular markers.

  Aradhya et al. Cladogram Comparing DNA Of Ficus carica Varieties (PDF)  

Magnified view of Ficus carica cultivar cladogram showing position of F. pseudocarica on sister clade with the 'Hacin' cultivar, between clades of the popular cultivars 'Zidi' and 'Roeding.'.

Ficus pseudocarica and F. palmata at test plots of UC Riverside in June 1985.

  More Images Of 'Vista Caprifig' Under Part 7 Above.  

The leaves of F. palmata are quite distinctive and match illustrations and photos of the tree in its native habitat from Ethiopia to India; however, according to Condit (1969) the leaves can also be deeply lobed. Condit lists Blastophaga psenes as the symbiotic pollinator wasp for F. palmata, the same species found in F. carica. K.J. Joseph (1954) reported B. vaidi for F. palmata in India, but Wiebes and Compton (1990) consider this species of wasp questionable because it is so similar morphologically to B. psenes. The nonpollinator wasps Sycoscapter forsteni and Philotrypesis palmata are also reported for F. palmata in India (S. van Noort and A. van Harten, 2006). Although the obligate mutualism between pollinating fig wasps and their host fig trees has historically been a one-to-one relationship, more than one species of pollinator wasp can be associated with a single host and, conversely, a single pollinator can be associated with more than one host fig species (van Noort and van Harten, 2006; van Noort and Rasplus, 2010).

Ficus pseudocarica is an enigma. In the DNA cladogram of Aradhya et al. (2010), the clade of a specimen identified as F. pseudocarica is embedded within clades of F. carica cultivars and yet it is considered synonymous with F. palmata. It seems reasonable to assume that if F. pseudocarica is synonymous with F. palmata and if F. palmata is a valid species, it should be in a clade separate from F. carica. These discrepencies suggest that perhaps some collections identified as F. pseudocarica in California are varieties of F. carica.

During the past two decades, a number of additional fig collections have been made in southern California by reputable botanists who concluded the species was Ficus palmata rather than F. carica. Eight of these are listed by the Consortium of California Herbaria at Rancho Santa Ana Botanic Garden and University of California, Riverside. DNA evidence strongly suggests that these two species are closely related; however, major herbaria such as Kew and Missouri Botanical Garden recognize them as distinct species. Although my 1986 caprifig collection from Vista, California (RSA381641) has some characteristics matching Condit's description of F. pseudocarica, it is perhaps best treated as a variety of Ficus carica.

In Ficus: The Exotic Species (1969) Condit discusses the difficulty in separating Ficus palmata from F. pseudocarica. In fact, in his Key To Ficus, the two species are not separated. Even the separation between these two species and Ficus carica is only based on the degree of pubescence of young stems. Ficus carica twigs are glabrous or only slightly puberulent, while those of F. pseudocarica and F. palmata are velvety pubescent. Other characteristics, such as leaf shape and size, venation, and the size, shape and color of fruit are so variable that it is difficult to make a positive identification from the key. Under his description of Ficus palmata, Condit cites George King who studied these species in the late 1800s: "I have a strong suspicion that all may be but forms of F. carica Linn." According to the extensive fig website FigWeb (2011), fig biologists Simon van Noort and Jean-Yves Rasplus state that F. palmata and F. carica are probably conspecific. The Principle of Parsimony (Occam's Razor) states that the least complex explanation for an oberservation is probably the best explanation. If F. pseudocarica, F. palmata and F. carica are all taxonomic varieties or subspecies of one species complex, the above discrepencies between DNA analysis and disputed California collections of these species might be resolved!

14. Ficus carica-F. palmata Complex & Possible Origin Of Ficus carica

Of all the different hypotheses regarding the origin of the Ficus carica-palmata complex, including F. pseudocarica, F. johannis & F. afghanistanica, there is one proposed by Louis Trabut a century ago that seems very plausible today. Trabut's article "Sur Les Origines du Figuier" appeared in the French journal Revue de Botanique Appliquee, Volume 2: 393-396 (1922). It is summarized here by Ali Sarkhosh, et al. in The Fig: Botany, Production and Uses, CAB International Publishers, one hundred years later (2022): Ficus carica may be a synthetic species derived from several wild species through natural hybridization. It is found near other closely related species or subspecies, such as F. persica, F. virgata and F. johannis; grown in southwestern Persia, Mesopotamia and Arabia. Trabut (1922) also mentions F. forskalaei & F. morifolia from Arabia and Abyssinia, Natural hybridization occurs between all these species, the resulting seedlings being exceedingly variable. F. palmata, though generally regarded as the Indian form of F. carica, is widely distributed from northern India to Afghanistan, Arabia, Egypt and Abyssinia. All the figs in this group are dioecious with female trees & male caprifigs in the populations. Throughout this vast area of the Middle East, they all have the same symbiotic pollinator wasp Blastophaga psenes. As noted in above paragraphs, misidentification between Ficus carica and F. palmata is common in herbaria and botanical gardens, and there is continuous variation between species in this complex.

Leaf variation from a single branch on 'Vista Caprifg' in Twin Oaks Valley: Upper & lower leaf surfaces from 2 leaves are shown. Based on leaf shape, they could have come from practically any tree in the Ficus carica-palmata complex. Leaf characteristics in dichotomous keys to species in this complex are not very useful.
Most of the fig "species" in the Ficus carica-palmata complex are listed as synonyms or
subspecies of each other in Kew Plants Of The World Online and World Flora Online

14A. Treatment Of 8 Species Of Ficus In Carica-Palmata Complex
Kew Plants Of The World Online & World Flora Online (WFO)

Note: Ficus carica L. is listed as an accepted species in both Kew & WFO.
  Did it evolve from following wild species complex through natural hybridization?

8 Species in Carica -
Palmata Complex
Kew Plants Of The
World Online
World Flora Online (WFO)
 F. afghanistanica Warb. 
syn. F. johannis ssp.
  afghanistanica (Warb.) Browicz
syn. F. johannis ssp.
  afghanistanica (Warb.) Browicz
 F. forskalaei Vahl. 
syn. F. palmata ssp. palmata
syn. F. palmata Forssk.
F. johannis Boiss.
= F. johannis Boiss.
= F. johannis Boiss.
F. morifolia Forssk.
syn. F. palmata ssp. palmata
syn. F. palmata Forssk.
F. palmata Forssk.
= F. palmata Forssk.
= F. palmata Forssk.
F. persica Boiss.
syn. F. johannis ssp. johannis
syn. F. johannis Boiss
F. pseudocarica Miq.
syn. F. palmata ssp.
virgata Browicz
syn. F. palmata ssp.
virgata (Roxb.) Browicz
F. virgata Roxb.
syn. F. palmata ssp.
virgata Browicz
syn. F. palmata ssp.
virgata (Roxb.) Browicz

Author names should be listed for accurate synonym comparisons. For example,
F. palmata Rosb. is a synonym of a different species F. grossularioides Burm.f.

Ira Condit was well aware of Trabut's hypothesis for the origin of Ficus carica. In chapter 3 of his book The Fig (1947), Condit discusses natural hybridization between all the species in the F. carica-F. palmata complex resulting in exceedingly variable seedlings: "Trabut hoped to be able to remake this synthetic species [Ficus carica] by bringing together all the related forms and by allowing them to interpollinate. He was able, however, to secure only F. palmata and F. pseudocarica. In California as in Algeria these two species have long been acclimatized and are being utilized in certain lines of plant breeding."

Regarding all these synonymous or very closely related species in the Ficus carica-palmata complex, there is one undeniable fact. The oldest officially named species is Ficus carica L., named by Linnaeus & published in Species Plantarum in 1753. According to the International Codes of Botanical Nomenclature, Rule (Law) of Priority, this is a correct name that should be used!

  Aradhya et al. Cladogram Comparing DNA Of Ficus carica Varieties (PDF)  

Disclaimer & Concluding 'Vista Caprifig' Remarks

My 'Vista Caprifig' originally came from a roadside creek in Vista, California. It is obviously a seedling caprifig that resembles characteristics of F. pseudocarica described in the literature. It is a prolific pollen producer in the June profichi crop and a prolific producer of fig wasps. Precaution: If it is planted near parthenocarpic fig varieties they will be pollinated and their second crop of syconia will be filled with seed-bearing endocarps. In my opinion the seeds enhance the flavor of my parthenocarpic varieties, such as 'Verte.' In addition, I have seedling figs appearing throughout my property in Twin Oaks Valley!

On Tuesday (22 March 2022) there were numerous fig wasps (Blastophaga psenes) emerging from my 'Vista Caprifig' mamme crop. They resembled miniature swarms of gnats around the branches loaded with profichi syconia.

'Vista Caprifig'

My 'Vista Caprifig' on Tuesday 22 March 2022. Left: Tree is loaded with green profichi crop of syconia with slightly larger, purple-gray, mamme syconia. Right: Numerous Blastophaga psenes were escaping from ostioles on mamme syconia and flying to receptive profichi syconia. Upon squeezing through ostioles on profichi crop their wings often break off, leaving a tuft of wings protruding from ostioles.

As I stated above, Smithsonian (March 2022) contains an article about hunting for "wild figs" in California, a competitive endeavor to locate superior female trees (varieties) that grew from viable seeds. Randomly searching for the best tasting wild female tree is highly subjective and certainly enjoyable, especially if you find one. My 'Vista Caprifig' seedling hybrid is a noteworthy caprifig. In my opinion it is different from typical F. carica and perhaps slightly different from original F. pseudocarica discussed in the literature. I have propagated cuttings to several fig growers and the campus of Palomar College. In the meantime I will continue to refer it as 'Vista Caprifig'.

15. Sex Determination By Genes & Chromosomes in Ficus carica

      G = dominant allele for short-style female flowers
      g = recessive allele for long-style female flowers
      A = dominant allele for production of male flowers
      a = recessive allele for suppression of male flowers
Dominant G & A genes linked on one chromosome.
    Recessive g & a genes on homologous chromosome.
Fig Genotypes:
Caprifig: GA/GA & Heterozygous GA/ga.
Female fig: Homozygous ga/ga ONLY.

Storey, W.B. 1975. "Figs." In: Advances in Fruit Breeding. J. Janick & J.N. Moore, Eds. Purdue Univ. Press, 1975.
Storey, W.B. 1955. "Sex Inheritance in Figs." Calif. Fig Institute. Proceedings of the Annual Conference 9: 15-17.

It is interesting to note that Dr. Storey's original discovery that sex determination in Ficus carica is under the control of a single autosomal locus, and that functional males are heterogametic for sex determination was corrobarated by T.L. Parish, H.O. Koelewijn, and P.J. van Dijk in 2004 (Sexual Plant Reproduction 17: 17-22). They studied DNA fragments (Amplified Restriction Length Polymorphisms or AFLPs) in the gynodioecious species Ficus fulva.

Seed Parents
Pollen Parents
Homo Caprifig (GA/GA)
[GA] only
Hetero Caprifig (GA/ga)
[GA] and [ga]
Homo Caprifig (GA/GA)
[GA] only
All GA/GA Male
1/2 GA/GA Male
1/2 GA/ga Male
Hetero Caprifig (GA/ga)
[GA] and [ga]
1/2 GA/GA Male
1/2 GA/ga Male
1/4 GA/GA Male
1/2 GA/ga Male
1/4 ga/ga Female
Female Fig (ga/ga)
[ga] only
All GA/ga Male
1/2 GA/ga Male *
1/2 ga/ga Female *

* = Most likely genotypic combination: Homozygous female tree x heterozygous caprifig.

  Sex Determination & Life Cycle Of Ficus carica  

16. 'Calimyrna' ('Sari Lop') Fig Orchard In San Joaquin Valley

Each June in California's hot San Joaquin Valley, paper bags containing wasp and pollen-bearing caprifigs are stapled to limbs in Calimyrna fig orchards. Only a few wasp-laden caprifig syconia are placed in the bags to prevent overpollination and split Calimyna fruit. Inside the paper bag (right), small black wasps can be seen exititing the caprifigs.

A wasp-pollinated Calimyrna fig containing numerous seed-bearing drupelets (minute ripened ovaries). In fact, the excessive pollination and seed production has caused the syconium to split open. The seed-bearing drupelets impart a superior nutty flavor to the fig newton (right).

17. The Actual Ripened Botanical Fruits Of A Fig

The actual botanical fruits of figs are the minute one-seeded drupelets that line the inside of the syconium. The syconium is a structure unique to Ficus. It is a hollow inflorescence lined on the inside by numerous unisexual, apetalous flowers. The ovaries of long-style flowers develop into one-seeded drupelets if they are pollinated.

In short-style female flowers, the wasp inserts her ovipositor down the stylar canal and lays an egg in the ovary of the flower. The subsequent larva feeds on endosperm tissue initiated by the ovipositing pollinator wasp. Since the endosperm in some figs may be initiated parthenogenetically (without pollination and fertilization), possibly by a mechanical or chemical stimulus during oviposition, food tissue for the developing larva functions like a minute gall. According to Saleeb (1965), the parthenogenetic endosperm of Ficus carica is the same as the sporphyte tissue (2n = 26), showing that it did not result from double fertilization. Style length is genetically controlled, and it is important for the tree to have style lengths longer than the wasp's ovipositor in long-style flowers so that seeds can develop in these ovaries. It is also important to have flowers with short styles so that female wasps can lay eggs (oviposit) in the ovaries. "Bogus" fig wasps (parasitoids and inquilines) with extra long ovipositors present a formidable problem to figs. They can readily lay eggs in long-style flowers, and can even penetrate the syconium wall without pollinating the female flowers inside. Some dioecious figs can counter this problem by simply aborting unpollinated syconia, thus ridding itself of seedless syconia. This strategy does not work on monoecious figs with multiple style lengths in the same syconium. Dioecious figs may represent an advanced (further evolved) species.

18. Overwintering Mamme Crop Of A Caprifig

Overwintering mamme crop of syconia on 'Vista Caprifig'.

'Vista Caprifig'

Left: Leafless (dormant) caprifig photographed in February 2009 showing overwintering mamme crop and spring profichi crop of syconia. Right: A fig wasp larva inside the ovary of a short-style female flower in an overwintering mamme syconium. The larva fed on parthenogenetic endosperm tissue in the mamme syconium that developed without pollination. The initiation of endosperm tissue after oviposition by the female wasp meets the criterion for gall formation. The larva consumes the galled tissue within the ovary wall. After metamorphosis, the adult male wasp chews a hole through the ovary wall and exits the female flower. He then crawls to another short-style female flower that contains a mature female wasp. He climbs up on the ovary of the flower, bites a fertilization hole in the ovary wall, and inserts his long, slender abdomen into the opening, thus inseminating the female. After being inseminated, the female crawls out of the fertilization hole through the ovary wall initially made by the male. My students and I observed this phenomenum many times during general biology laboratory sessions.

'Vista Caprifig'

A dozen female Blastophaga psenes crammed into the ostiole of receptive profichi syconium of a caprifig. Photographed 25 March 2009. These winged female wasps came from the overwintering mamme crop on the caprifig tree.

19. Why Can't Female Wasp Lay Her Eggs Inside Syconium Of Edible Fig?

Syconium of edible fig (female tree) lined on the inside with dense mass of long-style female flowers. Ovipositor of wasp is too short to penetrate the ovaries of these flowers, so she is unable to oviposit. Her wings typically break off as she squeezes through the ostiole and bracts. She will eventually die inside this syconium, but during her attempts to oviposit, she will pollinated the long-style female flowers. The ovaries of these flowers will develop into seed-bearing drupelets.

20. Vicarious Selection In Dioecious Figs

A plausible explanation why pollinator wasps don't evolve longer ovipositors so they can oviposit in the ovaries of long-style female flowers. Male and female syconia are virtually indistinguishable in external appearance. Selection takes place in male syconia of caprifig.

In his book "Climbing Mount Improbable (1996), Richard Dawkins devotes Chapter 10 to the fig/fig wasp coevolution and the model for vicarious selection proposed by Grafen and Godfray (Proceedings of the Royal Society, 1991). In vicarious selection of the dioecious fig subgenus Urostigma, morphology (style and ovipositor length), and wasp behavior (purposive loading and unloading of pollen) is taking place in wasps who enter and leave male syconia containing short-style female flowers on male trees. This selection is crucial for the perpetuation of fig trees when wasps enter female syconia on female trees (which superficially resemble male syconia). Female syconia produce seeds (the vital genetic link for fig trees) and are a genetic graveyard for wasps because they cannot oviposit in the long-style female flowers. The female wasps die in these syconia. For wasps in female syconia, mutations for a longer ovipositor that could reach the ovary of long-style flowers would not be passed on. For wasps in male syconia, there is no selective advantage for longer ovipositors because they are perfectly adapted for laying eggs in the ovaries of short-style flowers. Vicarious selection does not explain the evolution of ovipositor length in all figs, particularly the numerouas monoecious species. The fig/fig wasp scenario is much more complicated, with many variations in the life cycles depending on the different subgenera. Unfortunately, it is beyond the scope of this discussion.

   See Key To The Subgroups Of Dioecious Figs   

In about half of the fig species (referred to as monoecious), male flowers and the long and short-style female flowers occur in the same bisexual syconium; but in all other fig species (referred to as dioecious), the seed-producing, long-style female flowers only occur in unisexual syconia on female trees, while pollen-bearing male flowers and wasp-bearing, short-style female flowers occur in the same syconia on male trees. This latter arrangement is typical of the common fig. In fact, early fig growers in California's San Joaquin Valley were puzzled why their imported Smyrna figs would not set fruit. The trees didn't have their symbiotic wasp from Asia Minor and dropped their their crops of unpollinated syconia.

21. Parthenocarpic Varieties Of Ficus carica

There are many cultivated "parthenocarpic" varieties of the common fig in which the syconia develop on female trees without wasp pollination. The ripe syconia are fleshy and edible; however, the numerous ovaries (drupelets) inside are hollow and seedless. Examples of these varieties include 'Brown Turkey,' 'Mission' and 'Kadota.' The remains of parthenocarpic fig syconia in ancient settlements of the Jordon Valley indicate the people recognized natural parthenocarpic trees and propagated them by cuttings more than 11,000 years ago. According to fig connoisseurs, pollination produces a more delicious fig with a superior nutty flavor due to the seeds. In fact, the best fig newtons come from wasp pollinated 'Calimyrna' fig orchards in Fresno and Madera Counties. Most of the trees are female, but growers also maintain small groves of wasp and pollen-bearing male trees called caprifigs. The prefix capri refers to goat, and these inedible figs were fed to goats in the Old Word.

Fig Cultivation Predates Cereal Domestication

Kislev, M.E., Hartmann, A. and O. Bar-Yosef. 2006. "Early Domesticated
Fig in the Jordan Valley." Science 312 (5778): 1372-1374. 2 June 2006

The remains of parthenocarpic fig syconia (edible figs) have been discovered in archeological sites of the Jordon Valley that date back to 11,400 years bp. The carbonized syconia are clearly parthenocarpic because the drupelets are without embryos or seeds. Wild populations of Ficus carica are gynodioecious with male trees (caprifigs) and female trees. Edible figs are produced on female trees only if they are pollinated by fig wasps (Blastophaga psenes) from the syconia of male trees. The male syconia contain wasps and pollen, and are generally not eaten. They were named "caprifigs" because they were commonly fed to goats. If pollinated, seeds develop inside the drupelets within syconia on female trees. Without pollination, the immature figs are shed by the female trees. According to W.B. Storey (1975), parthenocarpy is produced by a single domant mutant gene. Female trees expressing this gene retain their developing figs to maturity, even though they are not pollinated and contain no seeds. Parthenocarpic trees must be propagated by cuttings because they do not produce seeds. They produce sweet fig fruits (syconia) without the need for male trees that carry symbiotic fig wasps within their syconia. This is very advantageous to farmers in regions where the wild caprifigs and natural pollinator wasps do not occur. The presence of parthenocarpic figs in ancient settlements indicates that people recognized these rare parthenocarpic trees and propagated them by planting branches. Evidence of such activity may mark one of the earliest forms of agriculture. Fig trees could have been the first domesticated plant of the Neolithic Revolution, which preceded cereal domestication by about 1,000 years.

Fig Cultivation May Not Predate Cereal Domestication

Lev-Yadum, S., Ne´eman, G., Abbo, S., and M.A. Flaishman. 2006. "Comment on Early
Domesticated Fig in the Jordan Valley." Science 314: 1683a. 15 December 2006

Parthenocarpic trees of Ficus carica produce 1 or 2 annual crops of seedless syconia (see Table of Fig Crops). They are all capable of producing seeds if they are pollinated by caprifigs containing fig wasps and pollen. These parthenocarpic syconia could have come from wild trees that grew from seeds. "Because all parthenocarpic fig types can produce seeds, the finds described in (1) cannot serve as an unambiguous sign of cultivation and lend no support to the notion that horticulture predated grain crops in the Near East."

Left: 'Brown Turkey', a parthenocarpic variety (cultivar) of the common fig (Ficus carica). Right: Another parthenocarpic variety of F. carica similar to 'Verte'. It produces a heavy 2nd (main crop) late in the fall (October-November). The syconia have a green outer skin and strawberry interior. This is the most delicious, sweet fig that I have ever eaten.

Seed-bearing endocarps of Ficus carica variety 'Verte' at the bottom of a dish of water. Although this cultivar is parthenocarpic, it has been pollinated by fig wasps from a nearby caprifig. Endocarps with mature, viable seeds typically sink in water. These are the actual fruits of a fig. They are the sclerified inner layer of tiny, ovule-bearing ovaries after the thin, fleshy, outer pericarp layer has been removed. Hollow (seedless) drupelets produced without pollination and fertilization are called cenocarps. If the endocarps contain wasp larvae they are called psenocarps.

Dried fig varieties from Bates Nut Farm, San Diego County. Left: Black Mission. Right: Calimyrna

  See More Parthenocarpic Varieties Of The Common Fig (Ficus carica)   

22. Dangers Facing The Emerging Female Fig Wasps

The emerging female fig wasp faces many dangers after she leaves the safety of her protective syconium. One of these dangers during wasp exodus from summer profichi and fall mammoni crops of syconia on Ficus carica are predators, including opportunistic spiders. The following image shows a minute orb weaver called the trashline spider (Cyclosa turbinata) that has built its web near a mammoni syconium of my 'Vista Caprifig'. On September 14, many wasps leaving the syconium fluttered into the web and were quicky caught by the tiny spider. This minute orb weaver spider (family Araneidae) is only about 5 mm long. It is called the trashline spider because it stores it victims, each rolled in cases of silk, in a vertical row in the center of the web.

'Vista Caprifig'

Argentine ants (Linepithema humile) are common on my large 'Vista Caprifig' during the Blastophaga exodus from profichi crop in early summer. These aggressive little ants undoubtedly attack the abundant female fig wasps. There is a well-documented acrobat ant (Crematogaster scutellaris) in Europe and the Mediterranean region that preys on the fig wasp (Blastophaga psenes), symbiotic pollinator of fig trees (Ficus carica) that inhabit this region.

  See Acrobat Ant Images From Croatia   

23. Which Figs Grew In The Ancient Holy Land?

Kalamata string figs. In ancient times people carried strings of dried figs such as these on long arduous journeys across the desert. The figs provided them with a nutritious high protein, high carbohydrate food source in a region where food was scarce.

An excellent article entitled "The History of the Fig in the Holy Land from Ancient Times to the Present" was written by Asaph Goor in Economic Botany 19: 124-135 (1965). The fig species discussed by Goor is the common edible fig (Ficus carica). This tree was cultivated for its fruit more than 11,000 years ago and is native to the region between the Mediterranean and Black Seas, sometimes referred to as the ancient region of Caria in Asia Minor. It is a dioecious species with separate male and female trees, and a symbiotic pollinator wasp (Blastophaga psenes) that is propagated inside the fruits (syconia) of male trees called caprifigs. It grows wild over a large area, including southern Europe and the Middle East. Goor (1965) stated that Ficus carica grew wild in the Holy Land thousands of years ago; however, this doesn't necessarily mean that it was truly native (indigenous) to the Holy Land. It may have been introduced by people to this region, either by seeds or cuttings.

According to M.E. Krislev, A. Hartmann, and O. Bar-Yosef, "Early Domesticated Fig in the Jordan Valley," Science 312: 1273-1275 (June 2006), the remains of parthenocarpic fig syconia (edible figs) have been discovered in archeological sites of the Jordon Valley that date back to 11,400 years bp. The carbonized syconia are clearly parthenocarpic because the drupelets are without embryos or seeds. Edible figs are produced on female trees only if they are pollinated by fig wasps (Blastophaga psenes) from the syconia of male trees. The male syconia contain wasps and pollen, and are generally not eaten. They were named "caprifigs" because they were commonly fed to goats. If pollinated, seeds develop inside the drupelets within syconia on female trees. Without pollination, the immature figs are shed by the female trees. According to W.B. Storey (1975), parthenocarpy is produced by a single domant mutant gene. Female trees expressing this gene retain their developing figs to maturity, even though they are not pollinated and contain no seeds. Parthenocarpic trees must be propagated by cuttings because they do not produce seeds. They produce sweet fig fruits without the need for male trees that carry symbiotic fig wasps within their syconia. This is very advantageous to farmers in regions where the wild caprifigs and natural pollinator wasps do not occur. The presence of parthenocarpic figs in ancient settlements indicates that people recognized these rare parthenocarpic trees and propagated them by planting branches. Evidence of such activity may mark one of the earliest forms of agriculture. Fig trees could have been the first domesticated plant of the Neolithic Revolution, which preceded cereal domestication by about 1,000 years.

Ficus carica and its symbiotic wasp have even been introduced into California, including male and female trees that grow wild in San Diego County. The symbiotic wasps live in a caprifigs that produce three crops of inedible figs (syconia) each year, including a wasp-bearing, overwintering mamme crop that remains on the bare branches when the tree is devoid of leaves. There are several varieties of male caprifigs and hundreds of varieties of female Ficus carica trees, some of which develop delicious, seedless, parthenocarpic fruits that do not require pollination. There are also varieties in which the female trees will shed their entire crop if they are not pollinated by the symbiotic fig wasp. These varieties have been selected by people over countless centuries. The trees are readily propagated by cuttings and were transported and cultivated by people thousands of years ago. Apparently many ancient civilizations were aware of the fact that Ficus carica required pollination in order to produce edible, seed-bearing fruits, a process called caprification. In 350 B.C., Aristotle described fig wasps that came out of caprifigs and penetrated the unripe female fig fruits, thus fertilizing them. Theophrastus (372?-287? B.C.) discussed caprification in detail, and Pliny (23-79 A.D.) devoted an entire chapter to the practice of caprification in Italy. The subject of fig pollination and "gallflies" in ancient Babylonia is also mentioned by Herodotus (Book I, 485?-425? B.C.). Early horticulturists were undoubtedly aware that the seeds impart a superior, nutty flavor to the fruit, and in some varieties the fruit will not set if it is not pollinated by fig wasps. The fig referred to in ancient Babylonia was probably Ficus carica, but another species called the sycomore fig (Ficus sycomorus) was also used for food in the eastern Mediterranean region. According to Goor (1965): "The sycomore fruit is much inferior and cheaper... It is eaten by the poorer classes and by shepherds in plains where it grows alone." In addition it does not survive cold winters like Ficus carica, and Ficus carica has a much wider range, particularly in colder regions of Iraq and northward.

An excellent article about ancient fig cultivation was written by J. Galil entitled "An Ancient Technique for Ripening Sycomore Fruit in East-Mediterranean Countries" (Economic Botany 22: 178-190, 1978). When the term "fig gashing" in the Near and Middle East is mentioned in various articles and books (including the Bible), it most likely refers to the sycomore fig (Ficus sycomorus). Although it is native to eastern Central Africa, the sycomore fig was carried north to the Middle East by 3000 BC. Without its native symbiotic pollinator wasp (Ceratosolen arabicus) the trees did not set fruit. Early farmers in this region learned how to induce parthenocarpy by gashing the syconia with a knife. Within 3-4 days the hard, green syconia enlarge and become sweet and fleshy. Gashed sycomore figs have been found in ancient tombs and are depicted in ancient bas-reliefs. Some biblical scholars think the phrase "gatherer of sycomore fruit" (Amos 7:14) actually means "piercer of sycomore fruit." The gashed figs produce ethylene gas which hastens the ripening process. Ethylene gas is also used on green bananas before they reach your supermarket.

There is also a nonpollinator wasp Sycophaga sycomori that lays eggs inside the female flowers of Ficus sycomorus. Symbiotic pollinator wasps of figs (including Ceratosolen arabicus) typically only lay eggs in short-style flowers within the syconium. Their ovipositors are too short to lay eggs in long-style flowers. Consequently, the long-style flowers do not contain wasp larvae and develop seeds instead. This is vital to the tree. The Sycophaga wasp has a longer ovipositor and lays egges in short- and long-style flowers. Therfore, sycomore fig syconia do not bear seeds, only Sycophaga wasps. Apparently the act of oviposition by Sycophaga wasps causes the seedless syconia to enlarge and ripen like gashed figs except they are full of wasps! The trees do not benefit from this relationship because no seeds are produced. Apparently there is also a parthenocarpic variety that will develop edible seedless syconia on its own without Sycophaga wasps. The latter figs do not require gashing. Again, these parthnocarpic (seedless) fruits are not advantageous to the fig tree. This is indeed a complicated subject.

According to J. Galil (1967) there are to ways that sycomore figs develop seedless parthenocarpic fruit without pollination in Israel. Apparently the nonpollinator wasp Sycophaga sycomori has now migrated to this region from Central Africa.

1. Stimulative Parthenocarpy: The nonpollinator wasp Sycophaga sycomori enters the immature syconia causing them to enlarge and develop (ripen) into seedless fruit full of wasps.

2. Vegetative Parthenocarpy: This is apparently a variety of sycomore fig that bears ripe seedless fruit on its own without wasps. This is similar to varieties of the common fig (Ficus carica) that bear edible seedless fruit without pollination.

  See Ancient Figs Of The Holy Land  

24. Fossil Fig Syconia In Wyoming & Montana?

Fossilized (petrified) fig syconia are very difficult to find because they decay rapidy. In 1881, a remarkable discovery was made in the Lance Formation of Converse County, Wyoming by J.B. Hatcher. The syconia had the perfect shape of a modern fig, with a narrowed neck region and a globose body. In fact, they were originally thought to be bulbs of a monocotyledonous plant. Most of the peduncles were broken, but an entrance to the interior (ostiole) at the opposite end was visible on some of the syconia. According to F.H. Knowlton (Bulletin of the Torrey Botanical Club Vol. 38) who described this species in 1911, the interior cavity was filled with course sandstone mixed with extraneous matter, such as bits of vegetation and fragments of shells. According to Knowlton (1911): "In no case was the cavity found to contain seeds, which seems rather remarkable considering the fine state of preservation of the fruit as a whole. It seems probable that when the neck was broken the larger, globose end, being heavier, floated downward and the fruits were filled and covered up in this upright position in which they are found."

The fossil fig was named Ficus ceratops by F.H. Knowlton (1911). The type locality where the original specimen was collected is also called "Ceratops Beds" because of the abundant fossils of late Cretaceous horned (ceratopsid) dinosaurs. These dinosaurs include the well-known Triceratops made popular in the movie Jurassic Park. It weighed up to 12 tons, larger than an elephant. It was armed with huge horns over one meter long and an enormous parrot-like beak with an incredibly strong bite force. Undoubtedy it needed this armor to defend itself against T-Rex that also roamed this region. Incidentally, Knowlton also named the Triassic conifer Araucarioxylon arizonicum in 1889, the state fossil of Arizona.

Petrified "fig syconia" from the badlands of eastern Montana (Dawson County). They were originally thought to be from an extinct species of fig (Ficus ceratops) dating back to the late Cretaceous Period (70 million years ago). Tracks and fossils of T-Rex have also been found in this region of Montana. Right: One of these so-called "fig syconia" is 70 million years old! The other two are dried Mission and Calimyrna figs purchased at a nearby grocery store. Note: The fine longitudinal striations are not characteristic of fig syconia. In fact, these "fig syconia" might actually be endocarps of an extinct palm. See following explanation: "Ficus ceratops May Not Be A Fig."

Fibrous mesocarp from the fruit of Normanbya normanbyi, a tropical palm native to rain forests of Australia. Similar longitudinal striations (fibrous mesocarp) occur on petrified "figs" (Ficus ceratops) from the badlands of eastern Montana. The similar fibrous mesocarp is strong evidence that this fossil fruit is not a fig syconium, but is actually an extinct 70 million-year-old palm named Spinifructus antiquus.
Ficus ceratops May Not Be A Fig!

Astrocaryum huicungo
Like so many other aspects of fig biology, even the identification of fossil syconia is controversial. Several authors have suggested that some of the fig-like fossils from the Hell Creek Formation might belong to a different plant family. According to Alan Graham (1962), the fossil syconia differ from fig fruits is several respects: "The 2-layered pericarp wall, coarse striations at the base of the globose portion of the specimens, and the collar at the proximal end of the stalk are not characteristic of Ficus fruits. These morphological features are evident, however, on fruits of Guarea (Melicaeae)." Elisabeth McIver (2002) has studied these "figs" associated with fossils of Tyrannosaurus rex from southwestern Saskatchewan, Canada. She has transferred them to the new taxon Spinifructus antiquus of an unknown family and order. She suggested that they may be from an arecoid palm with pear-shaped fruits similar to the genera Astrocaryum, Asterogyne or Barcella.

The above image shows the large seed-bearing fruits and endocarps of the starnut palm (Astrocaryum huicungo) from the Rio Napo, a tributary of the Amazon River in Ecuador. This palm is named from the starlike design surrounding the three germination pores an the wide end of endocarps. They have the fibrous longitudinal striations and general shape of Spinifructus. The apex of endocarps have three distinct germination pores that are not visible on the fossil Spinifructus antiquus (syn. Ficus ceratops). These palm fruits are produced in dense clusters.

Phytelephas aequatorialis

Astrocaryum alatum
Palm Fruits With Pointed Projections & Spines
Elisabeth McIver (2002) suggested that the fruits of Spinifructus antiquus might be similar to palms of the genus Astrocaryum. In his on-line article entitled "Dangerous Palms," Geoff Stein has a image of the spine-covered fruits of Astrocaryum alatum (upper right).

  See "Dangerous Palms" By Geoff Stein  

The preconceived stereotype of a fig is something resembling a pear-shaped edible fig (Ficus carica) or dried figs at the supermarket. This is the mistake I made when I first saw these permineralized fruits. Actually, most of the species of wild tropical figs that I have seen have smaller globose syconia. In addition, fig syconia have very little woody tissue and rot away quickly. Fresh edible figs have a very short shelf life and are commonly dried. Palm fruits occur in large, dense clusters and this would explain the occurence of numerous Spinifructus in one small chunk of ground. In addition, fruits of palms such as Astrocaryum are very fibrous with hard, woody endocarps that would permineralize well (i.e. the contents of lignified cells become replaced by minerals and the fruit literally turns into stone). The presence of spines on the outer pericarp rules out figs. It is interesting that the original description by J.W. Dawson (1875) mentions the spiny outer wall.

The first published name for this fossil "fig" was Aesculus antiquus because the original author J.W. Dawson thought it resembled an ancient species of Aesculus (horsechesnut or buckeye) in 1875. See the horsechestnut fruit (left) photographed in Montana. Apparently most of the fossils don't have the spiny fruit wall. With an outer spiny pericarp, this fossil simply cannot be a fig syconium (Ficus). Knowlton did not cite Dawson in his 1911 paper where he describes Ficus ceratops. He was apparently unaware of the spiny outer wall on this fruit. Since Dawson's name predates Knowlton's Ficus ceratops, Dawson becomes the parenthetical author and Elizabeth McIver becomes the new author: Spinifructus antiquus (Dawson) McIver.

Like Knowlton's logs of Petrified Forest National Park (Araucarioxylon arizonicum) that were renamed Pullisilvaxylon arizonicum by R. A. Savidge in 2007, Knowlton's infamous Ficus ceratops has also been renamed by E. McIver in 2002.

  A Taxonomic Problem With Araucarioxylon arizonicum  

A 60 million-year-old fig leaf embedded in hard-rock limestone from the Fort Union Formation near Glendive, Montana. This fossil-rich strata is from the Paleocene Epoch that immediately followed the mass extinction event of dinosaurs at the end of the Cretaceous Period, known as the K-T boundary (Cretaceous-Tertiary boundary). The term Paleocene ("early-recent") refers to a time period when dinosaurs were replaced by smaller mammals, long before modern mammalian orders emerged. The best explanation (scientific theory) for the demise of non-avian dinosaurs is an enormous 10 km (6 mile) diameter asteroid that collided with the earth causing a global dust cloud that blotted out the sun for many months. Estimates as high as 85 percent of all species disappeared from the face of the earth at this time. This catastrophic event forever changed the direction of the evolution of life on earth.

The K-T boundary is clearly visible in Makoshika Stae Park near Glendive, Montana. It is a dark, narrow band of sediments and carbonized plant material (coal) that separates the Cretaceous and Tertiary periods about 65 million years ago. The tan strata above the K-T band is called the Fort Union Formation. It is younger than 65 million years and does not contain dinosaur fossils. Below the K-T band is the older brownish-gray Hell Creek Formation that is rich in dinosaur fossils, including Tyrannosaurus rex, Triceratops, the amazing duck-billed Hadrosaurus, and the so-called petrified "figs" (Spinifructus antiquuas).

In 1980, a team of researchers consisting of Nobel prize-winning physicist Luis Alvarez, his son, geologist Walter Alvarez, and chemists Frank Asaro and Helen Michels discovered that sedimentary layers found all over the world at the K-T boundary contain a concentration of iridium many times greater than normal. Iridium is a rare earth element that is abundant in most asteroids and comets. It is the second densest element after osmium and the most corrosion-resistant metal. The Alvarez team suggested that an asteroid struck the earth at the time of the K-T boundary.

Above the 65 million year old K-T boundary is the Fort Union Formation & below is the Hell Creek Formation.

Fossil fig leaves have also been reported from the Madro-Tertiary Geoflora in California by Daniel Axelrod (1958). This habitat consisted of semiarid live oak-conifer woodland, chaparral and grassland. Ira Condit (The Fig, 1947) received the following letter from famous paleobotanist Ralph Chaney in 1943: "I have seen a leaf of the carica type from the Miocene of southern California and have no doubt that its relationship to F. carica is extremely close."

25. Index Of On-Line Fig Articles On Wayne's Word

  1. The Sex Life Of Figs: Palomar College Lecture by WPA
  2. A Petrified Fig Syconium From The Cretaceous Period
  3. Bogus Nonpollinator Fig Wasps With Long Ovipositors
  4. Calimyrna Fig & Its Amazing Pollinator Wasp
  5. Caprifig Fig Overwintering Mamme Crop
  6. Cauliflory In Tropical Species Of Figs (Ficus)
  7. Coevolution Of Fig & Fig Wasp: Vicarious Selection
  8. Evolution Of Dioecious Fig Species
  9. Ficus dammaropsis: A Remarkable Fig From New Guinea
  10. Fig Pith Sculpture: Microscopic Carvings From The Azores
  11. Figs Of The Holy Land (Their Role In World Religions)
  12. Gall Controversy: Do Fig Wasps Really Induce Gall Formation?     
  13. Hybrid Between Common Edible Fig & Creeping Fig
  14. Multiple Fruits Of The Mulberry Family (Moraceae)
  15. Pollination Patterns In Dioecious Figs
  16. Sex Determination & Life Cycle Of Common Fig (Ficus carica)
  17. Sexuality In Figs--Plant Sexuality & Political Correctness
  18. Strangler Figs & Banyans: Truly Remarkable Trees
  19. Summary Of Common Fig (Ficus carica) Life Cycle
  20. The Amazing Fig/Fig Wasp Relationship
  21. The Creeping Fig (Ficus pumila)--Source Of Grass Jelly
  22. Vicarious Selection In Figs (Richard Dawkin's Model)
  23. Wild Figs (Higueras) In Baja California & Gulf Islands
  24. Reference Articles Cited In The Above On-Line Pages

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