Delicious Figs In California's Central Valley This is a Smyna-type cultivar grown in the San Joaquin Valley of California. It is also called 'Sari Lop' and was introduced into California (Fresno area) in the late 1800s. No crop was produced until 1900, after the successful introduction of the fig wasp (Blastphaga psenes). The World's Most Delicious Figs Require A Tiny Symbiotic Wasp To Pollinate Its Minute Flowers See Unusual Hybrid Between The Common Fig & The Creeping Fig

Each June in California's hot San Joaquin Valley a most remarkable biological phenomenon takes place. Traveling north of Fresno on Highway 99, thousands of acres of Calimyrna fig orchards are "decorated" with small brown or white paper bags. This unusual annual event results in the delicious nutty flavor of Calimyrna figs and the crunch in your fig newtons.

To fig connoisseurs, Calimyrnas are the ne plus ultra (nee-plus-UL-tra) of figs. Comparing them with other cultivated varieties is like comparing red snapper with swordfish or hamburger with filet mignon. If you don't particularly like figs, you probably have never tasted a fresh Calimyrna. Since they are extremely perishable, most of the Calimyrna crop is used for dried figs, confectioneries and pastries.

In a strict botanical sense fig "fruits" are actually inside-out flower clusters (inflorescences) called syconia. They are hollow, fleshy structures composed of modified stem (peduncular) tissue, lined on the inside with hundreds of minute flowers. At one end is a small opening (ostiole) lined with dense, overlapping scales. Calimyrna syconia contain only female flowers and must be pollinated in order to ripen. Each tiny flower consists of a five-parted calyx and an ovary with a long style. Following pollination and fertilization the ovaries develop into minute one-seeded drupelets with a hard inner layer (endocarp) surrounding the seed. The seed-bearing drupelets produce the superior nutty flavor and crunch. Without pollination Calimyrna syconia fail to ripen and drop from the branches.

Up until the late 1800s, Calimyrna growers in California were puzzled as to why their trees would not set fruit. It was finally discovered that they needed a tiny female wasp pollinator from Asia Minor (Blastophaga psenes) that lives inside the fruits of pollen-bearing wild figs (called caprifigs). Capri refers to goat and the inedible wild figs were apparently fed to livestock. The tiny wasps are only two millimeters long, small enough to pass through the "eye" of a sewing needle. Wasp-bearing caprifigs are now grown in California, and each summer they are placed in the little brown bags in Calimyrna orchards. This process, called caprification, is vital to the Calimyrna growers.

By June the fig wasps living inside caprifig syconia are mature. At this time the male flowers inside are shedding copious pollen and the ostiolar scales are loose and passable. The gravid female fig wasp (already inseminated by a male) becomes dusted with pollen as she crawls out of the caprifig syconium. She flies to a Calimyrna branch where she instinctively forces her way through the ostiole of a receptive syconium. As she squeezes through the pore her wings often break off and protrude from the opening. In fact, this is how you can tell if a wasp has entered the unripe Calimyrna. Only in small receptive syconia can the female wasp enter the ostiole and push through the inner layer of closely overlapping scales. After this stage the ostiole is virtually impervious to insect entry. Inside she attempts to lay an egg inside the ovary of each female flower by inserting her ovipositor (egg-laying device) down the slender style. In Calimyrna figs this turns out to be a lesson in futility because the styles are all too long (much longer than her ovipositor). She withdraws her ovipositor and moves from one flower to another. In her desperate attempt to lay eggs she inadvertently pollinates the flowers. Eventually she dies from shear exhaustion, or old age, and is broken down by a protein-digesting enzyme (ficin) inside the fig. [In French Polynesia the ficin-rich sap from a native banyan fig is used to kill parasitic worms and to treat skin cancers.]

Female wasps lucky enough to live in a grove of wild caprifigs will be able to carry out their instinctive tasks. She can easily lay eggs inside the short-style flowers of caprifigs and perpetuate her offspring. Some of these may end up in Calimyrna groves the following summer. Lucky for us she can't lay eggs in Calimyrna figs--otherwise we might have a mouthful of fig wasps.

Most authors refer to the short-style female flowers inside the syconia of caprifigs as "gall flowers," presumably because they are commonly occupied by a developing fig wasp; however, they are fully capable of producing normal seed-bearing drupelets, and in this respect are no different from long-style flowers of Calimyrna figs. A gall may be defined as an abnormal swelling or tumorous growth on plants, caused by an insect whose larvae feed on the gall tissue. The fig wasp larva is clearly a seed predator feeding inside the ovary of a normal flower.

The "gall controversy" of fig flowers is complicated because food tissue (endosperm) for the developing larva may be initiated parthenogenetically (without pollination and fertilization), possibly by a mechanical or chemical stimulus during oviposition. In this case the flower functions like a minute gall, except their is no apparent tissue malformation as in typical insect galls. Functional male caprifigs of Ficus carica produce three crops of syconia per year: the summer profichi, fall mammoni and overwintering mamme that mature the following spring. Only the profichi crop produces pollen, and this is used to pollinate the Calimyrna orchards of California's Central Valley. [There are also reports of the mammoni crop of Ficus pseudocarica producing pollen in the fall.] The receptive mamme and profichi syconia are not pollinated, so endosperm tissue to nourish the wasp larvae in these crops must be initiated parthenogenetically. Whether they contain a mature seed or a wasp, the short-style flowers of caprifigs appear virtually identical in structure, and do not fit the definition of a typical gall. However, proponents of gall flower terminology argue that when the wasp induces the formation of nutritive endosperm tissue, the ovary interior is literally transformed into a minute gall.

Many authors dating back to Aristotle and Theophrastus thought the caprifig was the wild form of Ficus carica, while the female trees bearing edible figs were cultivated. They are actually two natural sexual forms of the same species. Caprifigs are naturalized in moist riverbeds and creeks of southern California amidst thickets of willows and cottonwoods. They occasionally appear as seedling volunteers in urbanized areas, probably dispersed by birds. The syconia contain clusters of pollen-bearing male flowers (each with five stamens) in the ostiolar region. During wasp exodus season in June they are filled with black, winged female wasps and amber, wingless males, and literally "smoke" with pollen. Some caprifigs in northern San Diego County have smaller, purple syconia and velvety-pubescent branchlets. These trees may be the closely related Ficus pseudocarica. Several cultivated varieties of caprifigs are sweet and palatable, including the Cordelia and Brawley.

As stated above, caprifigs of Ficus carica produce three crops of syconia per year: the profichi which ripen in early summer; the mammoni which ripen in fall; and the mamme which overwinter on the tree and ripen in spring. The pollen-bearing profichi crop is used to pollinate the Calimyrna figs in June. The overwintering mamme crop house wasps through the cold winter months and are quite visible on the leafless branches. Female trees produce only two crops of syconia annually, a breba crop which ripens in early summer and a second (main) crop which ripens in fall. During the receptive (immature) summer stage, this second crop receives pollen from the mature caprifig profichi crop. Although caprifig syconia incubate and perpetuate the tiny fig wasp, seeds may also develop in the short-style flowers. This is especially true of mammoni syconia in which pollination (from profichi crop) results in some ovaries (without wasps) developing seeds with viable embryos.

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 are predators, including opportunistic spiders. The following four images show a minute orb weaver called the trashline spider (Cyclosa turbinata) that has built its web near a mammoni syconium of Ficus pseudocarica. On September 14, many wasps leaving the syconium fluttered into the web and were quicky caught by the tiny spider. They were immediately rolled into balls of silk and stored in a vertical row in the center of the web.

One hazard of wasp pollination is the transmission of internal rot fungus or endosepsis (Fusarium moniliforme var. fici) from caprifigs to Calimyrnas. In early spring the entire mamme crop is harvested. Sound syconia are split open and dipped in a fungicide. They are placed back in the caprifig trees so emerging wasps can enter the receptive profichi crop. Since the mamme crop does not shed pollen, the mere act of oviposition stimulates endosperm formation and food tissue for developing larvae within ovaries of profichi syconia.

Most tropical species of Ficus bear several crops of syconia throughout the year, with short and long-style female flowers and male flowers in the same syconium. Since the female flowers are receptive several months before the male flowers release pollen, they require wasp pollination between synchronized syconia of the same or different trees. There are more than 1,000 recognized species of Ficus in the world, and each one has its own species of wasp. Pollination and seed production is essential for the dispersal and perpetuation of fig species and their symbiotic wasps.

In his monograph on cultivars of edible figs (Hilgardia: 11: 323-538, 1955), Ira J. Condit lists 471 varieties of common-type female trees of Ficus carica that do not require caprification. Several popular varieties grown in southern California include the Mission, Kadota, Brown Turkey and Conadria. Unlike the Calimyrna, the syconia remain on the branches and ripen without wasp pollination. The drupelets inside develop parthenocarpically and the crunchy little endocarps are generally hollow and without mature seeds. The cultivar Mary Lane has very little sclerified (woody) tissue in its endocarp and is ideally suited to denture wearers. Occasionally, female trees may produce apomictic seeds without pollination and fertilization: The seed embryo develops from an unfertilized egg (or another cell within embryo sac), or from nucellar tissue surrounding the embryo sac. Apomictic seeds enable the propagation of choice edible fig cultivars without the transmission of a mosaic virus disease through cuttings (need reference here).

Calimyrna figs are a high-energy, nutritious fruit, high in vitamins, calcium, phosphorus and iron. They are easily digested and are an excellent source of natural fiber. One large dried fig contains about 65 dietary calories (kilocalories). The California Fig Institute located in Fresno has prepared an extensive list of delectable fig recipes, from fig muffins and cookies to fig puddings and pies.

So the next time you enjoy a dried Calimyrna fig, or munch on a premium fig newton, think about the female wasps that literally gave their lives to make this delicious fruit possible.

Other WAYNE'S WORD Links About Figs & Their Wasps:

Index Of All Wayne's Fig Articles Nonpollinator (Bogus) Fig Wasps The Fig Gall Controversy Fig & Fig Wasp Relationship Sex Determination Of Common Fig Pollination Patterns In Dioecious Figs Sexuality Of Figs & Other Plants Figs Of The Holy Land

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Fig References Armstrong, W.P. 1995. "To Be Or Not To Be A Gall." Pacific Horticulture 56: 39-45. Armstrong, W.P. 1988. "The Calimyrna Fig and Its Wasp." California Garden 79: 135-138. Armstrong, W.P. and S. Disparti. 1988. "Wild Figs and Wasps of the Californias." Environment Southwest No. 521: 7-11. Condit, I.J. 1955. "Fig Varieties: A Monograph." Hilgardia: 11: 323-538. Condit, I.J. 1947. The Fig. Chronica Botanica Co., Waltham, Mass. Condit, I.J. 1920. "Caprifigs and Caprification." California Agriculture Experimental Station Bulletin 319: 341-377. Krislev, M.E., Hartmann, A. and O. Bar-Yosef. 2006. "Early Domesticated Fig in the Jordan Valley." Science 312 (5778): 1273-1275. Galil, J. 1977. "Fig Biology." Endeavour 1: 52-56. Galil, J. 1968. "An Ancient Technique for Ripening Sycomore Fruit in East-Mediterranean Countries." Economic Botany 22: 178-190. Galil, J. 1967. "Sycomore Wasps From Ancient Egyptian Tombs." Israel Journal of Entomology II: 1-10. Galil, J. and D. Eisikovitch. 1974. "Further Studies On Pollination Ecology in Ficus sycomorus. II. Pocket Filling and Emptying by Ceratosolen arabicus." Magr. New Phytol.. 73: 515-528. Ramirez, W. 1969. "Fig Wasps: Mechanism of Pollen Transfer." Science 163: 580-581. Ramirez, W. 1974. "Coevolution of Ficus and Agaonidae." Annals of the Missouri Botanical Garden 61: 770-780. Storey, W.B. 1975. "Figs." In: Advances in Fruit Breeding, Purdue Univ. Press, 1975, pp. 568-589.] Storey, W.B., Enderud, J.E., Saleeb, W.F., and E.M. Nauer. 1977. The Fig. Jurupa Mountains Cultural Center, Riverside, California.

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