The araucaria family (Araucariaceae) contains three remarkable genera of cone-bearing trees: Araucaria, Agathis and Wollemia. They are tall trees native to forested regions of South America and Australia. In majestic size and beauty, they certainly rival the coniferous forests of North America and Eurasia. In fact, they are considered the southern counterpart of our northern pine forests. The type genus Araucaria is derived from "Arauco," a region in central Chile where the Araucani Indians live. This is also the land of the "monkey puzzle" tree (A. araucana), so named because the prickly, tangled branches would be difficult for a monkey to climb. Fossil evidence indicates that ancestral araucaria forests resembling the present-day monkey puzzle date back to the age of dinosaurs. In fact, it has been suggested that the tree's armor of daggerlike leaves was designed to discourage enormous South American herbivorous dinosaurs, such as Argentinosaurus weighing an estimated 80 to 100 tons! Another ancient South American species called pino paraná or paraná pine (A. angustifolia) grows in southern Brazil and Argentina.

Australian members of the Araucariaceae include the prickly-leaved bunya-bunya (A. bidwillii) with huge pineapple-shaped cones, the hoop pine (A. cunninghamii) an important Australian timber tree, the Cook pine (A. columnaris) native to New Caledonia, and the Norfolk Island pine (A. heterophylla) native to Norfolk Island. [Both islands are located off the east coast of Australia.] The latter species is commonly grown in containers in southern California and is sold as "star pine" because of its horizontal tiers of radiating limbs. Throughout San Diego County "star pines" can easily be recognized by their tall, slender spires of tiered limbs. This species was discovered by Captain James Cook during his second voyage to Australia and New Zealand (1772-1775). The closely related Cook pine of New Caledonia that is naturalized throughout the Hawaiian Islands is named after this famous English explorer. Like the Norfolk Island pine, the bunya-bunya has an unmistakable silhouette with its barren, horizontal limbs tufted at the ends with spiny leaves. The huge seed cones of tall trees pose a serious threat to unsuspecting persons sitting beneath its cone-laden limbs.

Also in the araucaria family is the genus Agathis with more than a dozen species of large, resinous trees scattered throughout Australia, New Zealand and the Malay Archipelago. Several species of Agathis are the source of timber and valuable copal varnish, including kauri pine (A. australis), amboina pine (A. dammara) and dammar pine or Queensland kauri (A. robusta). Copals are a group of resins that form particularly hard varnishes. In addition to Agathis, there are New World sources of copal from resinous leguminous trees, including the West Indian locust (Hymenaea courbaril) and several species of Copaifera. Dammars are another group of hard, durable varnishes that turn shiny and transparent when dry. Although some species of Agathis are named dammar, most dammar resins come from tropical Asian trees of the genus Shorea in the Diptocarpaceae. Copals and dammars are used extensively in oil paintings. When painting with oils, colored pigment is squeezed onto a palette and then taken up in a thinning solution of linseed oil mixed with either copal or dammar. The resins "hold" the paint when dry and provide the luminous depth characteristic.

In 1994, David Noble discovered an unknown cone-bearing tree in rugged Wollemi National Park northwest of Sydney, Australia. About 40 trees in deep narrow canyon turned out to be an undescribed species. They were named Wollemi pine (Wollemia nobilis), a remarkable new member of the Araucariaceae. This rare conifer was thought to be extinct because its last fossil record was dated at about two million years ago. Choroplast DNA studies show no discernable genetic variation among the 40 trees. Like the rare Torrey pine (Pinus torreyana) of San Diego County, this is truly a relict population that was more widespread millions of years ago. Because of its small population size, a lot of its genetic diversity has been lost through thousands of years of isolation. The Wollemi pine is a great botanical discovery and is truly a "living fossil." Trees are being propagated from seeds, and who knows, maybe some day this tree will be cultivated in San Diego County like other living fossils such as the maidenhair tree (Ginkgo biloba) and dawn redwood (Metasequoia glyptostroboides).

Although they are often referred to as pines, members of the araucaria family have seed cones and foliage that is very different from the pine family (Pinaceae). Conifers in the pine family have cone scales with a pair of ovules (seeds) on the upper surface. Each cone scale is subtended by a distinct bract which is conspicuously exerted in some California species, such as the Douglas fir (Pseudotsuga menziesii) and Santa Lucia fir (Abies bracteata). Members of the araucaria family have only one ovule per scale and have bracts that are fused to the scale or none. Unlike the long, slender needles of pines (Pinus), araucarian leaves are typically short, overlapping and often prickly. Some species have broad leaves that superficially resemble leaves of flowering plants. In their native habitats, the araucarias become tall timber trees up to 200 ft. (61 m).

Back To Palomar College Araucaria Page   Fossil evidence indicates that the araucaria family reached its maximum diversity during the Jurassic and Cretaceous periods between 200 and 65 million years ago, with worldwide distributions. At the end of the Cretaceous, when dinosaurs became extinct, so did the Araucariaceae in the northern hemisphere. Until about 135 million years ago, trees of the Araucariaceae grew in forests of the southern supercontinent called Gondwanaland, when South America and Africa were connected with each other and with Anarctica, India and Australia. By 65 million years ago, the continents had divided into positions resembling their present-day configuration. During this time interval, araucariads began a slow decline in range and diversity as flowering plants, better adapted to climatic changes, began to evolve and gradually displace conifers. In 1915 Alfred Wegener, a German climatologist and geophysicist, published an expanded version of his 1912 book The Origin of Continents and Oceans. This novel hypothesis, which has now been confirmed by other scientists, states that continents are not fixed; instead, their relative positions and the positions of the oceans have changed over time. Wegener's hypothesis led to the science of plate tectonics, where scientists study the gradual movement of large plates of the earth's crust along major fault zones. About 200 million years ago, the continents were joined into one supercontinent that Wegener called Pangea (Figure A). By 135 million years ago, Pangea had divided into two large subcontinents called Gondwanaland and Laurasia (Figure B). In the great southern subcontinent Gondwanaland, South America and Africa were connected with each other and with Antarctica, India, and Australia. This is roughly the time when the first flowering plants began to appear on earth. By 65 million years ago, about the time when dinosaurs became extinct, the continents had divided into positions resembling the present-day configuration (Figure C). As of April 2000, the continents resembled the configuration shown in Figure D. Petrified Forest National Park in northeastern Arizona contains hundreds of acres of perfectly preserved logs from an ancient conifer forest that dates back to the late Triassic Period (approximately 225 million years ago). The trees of this forest coexisted with dinosaurs. Most of the petrified logs were previously assigned to the extinct species Araucarioxylon arizonicum, a presumed distant relative of Araucaria; however, new evidence indicates that these fascinating deposits of petrified logs represent a broad diversity of conifer species. Streams carried dead logs into this once swampy lowland region where they were buried in sediments rich in volcanic ash. Over countless centuries, the woody tissue has been replaced by minerals and gradually turned into stone. These ancient trees flourished during a time when all of the continents were united into the vast supercontinent Pangea. The area of Petrified National Park was located near the equator, at approximately the latitude of present-day Central America. Many of the reddish, agatized logs do not show cellular detail; however, there are some permineralized specimens in which minerals permeated the porous cell walls and filled the cell cavities (lumens). Thin sections of these samples viewed under a microscope show remarkable cellular detail. Petrified Wood Near Cameron, Arizona Petrified wood fragments in northern Arizona near Cameron. These are probably from the Chinle Formation dating back to the Triassic Period, approximately 200 million years ago. End view of one of the above wood fragments in its natural state. It was not altered (sectioned or polished). The fine grain structure shows perfectly preserved tracheids viewed in a transverse (cross section) plane. This wood predates the larger vessels characteristic of angiosperms. Photo taken with a hand held Nikon D-90 and SB 400 Flash using a 60mm Micro Nikkor AF-S F/2.8G ED Macro Lens. Camera settings: ISO 200, F22, 1/200. The high density, thick-walled tracheids and parallel rays resemble some of the images in the Online Publication by Dr. Rodney A. Savidge (2007), particularly the genera Pullisilvaxylon and Chinleoxylon (previously listed under Araucarioxylon arizonicum). Note: The average diameter of one tracheid cell lumen in cross section is about 30-40 µm. The resolving power of an unaided human eye with 20-20 vision is about 70 µm. Therefore, the cellular detail in above wood fragment is invisible to the naked eye.    See A Taxonomic Problem With Araucarioxylon arizonicum    Savidge, R.A. 2007. "Wood Anatomy of Late Triassic Trees in Petrified Forest National Park, Arizona, USA, in Relation to Araucarioxylon arizonicum Knowlton, 1889." Bulletin of Geosciences 82 (4): 301-328. Cross section of petrified wood fragment from Cameron, Arizona compared with a modern pine stem. Both stem cross sections show two spring growth periods with larger tracheids separated by a narrower summer growth band with smaller tracheids. The petrified wood dates back to the Triassic Period, approximately 220 million years ago. Left: Vessels in midvein of petal from Brodiaea terrestris ssp. kernensis. The spirally-thickened secondary cell walls appear like coiled springs. This provides strength as well as flexibility to these strands of tubular, water-conducting cells that compose the xylem (vascular) tissue. Right: Two types of water-conducting cells: tracheid and vessel (vessel element). Technically a vessel is composed of many hollow vessel elements joined end-to-end like sections of PVC pipe. With the exception of the Gnetophyta, most gymnosperms lack vessels. Vessels are characteristic of all flowering plants, except for the earliest ancestral sister clade (Amborella) that have only tracheids like most gymnosperms. Although the binomial Araucarioxylon arizonicum has been used in the literature for more than a century, Rodney A. Savidge of the University of New Brunswick (Bulletin of Geosciences Vol. 82 No. 4: 301-328, 2007) states that it is superfluous and therefore an illegitimate name (nomen superfluum). He examined thin sections of the original three specimens (syntypes) housed at the Smithsonian Institute upon which the species was first described by F.H. Knowlton in 1889. He concluded that they represented different species within two new genera of extinct trees. According to the International Code of Botanical Nomenclature, a valid species can have only one type specimen or holotype. Consequently, only one of the three specimens was retained as the new type or lectotype Pullisilvaxylon arizonicum. Savidge examined several other logs previously identified as A. arizonicum and concluded that they also represented additional new genera and species. His extensive anatomical studies indicate that the majority of logs at Petrified Forest National Park do not belong to a single species. It appears that the superfluous name "A. arizonicum" actually refers to a complex of extinct conifers. Based solely on the tracheid structure of permineralized wood (including resin canals, rays and tracheid pitting), and without DNA evidence, it is difficult to be certain which trees in the complex are ancestral relatives of the araucaria family. According to Dr. Savidge (personal communication, 2008), an immense amount of research into petrified woods is needed before the ancestries leading to modern trees will be clearly understood. At this time it would be purely conjectural to assign a scientific name to most logs in Petrified Forest National Park without detailed microscopic examination of the wood. Trees of "Araucarioxylon arizonicum" grew to a height 200 feet (61 m) with a trunk diameter from 4 to 9 feet. According to Sidney R. Ash and Geoffrey T. Creber (Paleontology Vol. 43 No. 1: 15-28, 2003), the living tree did not closely resemble any of the present-day Araucaria trees of the southern hemisphere as postulated in past reconstructions. The branches did not occur in whorls as they do in most conifers, instead they grew irregularly along the trunk. Sydney Ash and Rodney Savidge also studied the bark anatomy of Araucarioxylon arizonicum ("The Bark of Late Triassic Araucarioxylon arizonicum from Petrified Forest National Park, Arizona," IAWA Journal 25 No. 3: 349-368, 2004), and concluded that it was quite unlike the banded bark of extant Araucaria heterophylla. These ancient conifers grew in a tropical rain forest with marshes and river lakes, in an environment very different from today's Arizona landscape. Petrified Forest National Park in Arizona contains hundreds of acres of perfectly preserved logs from an ancient tropical flood plain during the late Triassic Period (over 200 million years ago). The trees of this extinct forest coexisted with dinosaurs. Many of the petrified logs have been assigned to the genus Araucarioxylon, a presumed distant relative of Araucaria; however, new evidence indicates that these petrified logs represent a broad diversity of conifer species. Streams carried dead logs into this once swampy lowland region where they were buried in sediments rich in volcanic ash. The woody tissue of the logs became impregnated with minerals such as silica and gradually turned into stone.   Perfectly Preserved Stems From Petrified Forest National Park   Trees of the "Araucarioxylon arizonicum" grew to a height 200 feet (61 m) with a trunk diameter from 4 to 9 feet. According to Sidney R. Ash and Geoffrey T. Creber (Paleontology Vol. 43 No. 1: 15-28, 2003), the living tree did not closely resemble any of the present-day Araucaria trees of the southern hemisphere as postulated in past reconstructions. These ancient conifers grew in a tropical region with marshes and river lakes, an environment very different from today's Arizona landscape.

Most older references list four species of Araucaria commonly cultivated in southern California, including A. heterophylla (Norfolk Island pine), A. bidwillii (bunya-bunya), A. cunninghamii (hoop pine), and A. araucana (monkey puzzle). The latter species does not do well in the arid climate of southern California; however, I have seen small trees in parks and gardens of central and northern California. The Norfolk Island pine typically has well-spaced, tiered, horizontal limbs and a distinctive silouette that is easy to spot from a distance; however, there are also trees with more closely-spaced limbs and a columnar, slender crown resembling the Cook pine (A. columnaris). According to Trees of Hawaii by Angela Kepler (1990), most of the trees called Norfolk Island pine in Hawaii are actually Cook pines. They are naturalized throughout the Hawaiian Islands and have been exported as lumber and container-grown "Christmas trees" to the U.S. mainland. So it looks like some our southern California Norfolk Island pines are actually Cook pines, particularly if they were imported from Hawaii.

According to M.G. Buck and R.H. Imoto (1982), Norfolk Island and Cook Pines were introduced to Hawaii in 1860. The two species probably hybridized and were subsequently dispersed throughout the islands. All juvenile trees today show A. columnaris traits and should probably be labeled as A. heterophylla x columnaris. The trees are commonly propagated by seedliface="arial"ngs. If these are exported to the mainland, it is possible that some of our cultivated specimens are indeed hybrids. Research forester P.G. Scowcroft (1988) states that Araucaria columnaris is the most abundant Araucaria species in the Hawaiian Islands, and that A. heterophylla is sparsely represented in Hawaii. According to Elbert L. Little, Jr. and R.G. Scolmen (1989), some exported seeds may be hybrids; however, hybridization is unlikely because the two species shed pollen six months apart. in addition, seed and foliage samples sent to Kew Gardens were all identified as A. columnaris. Dr. Little also states that seeds of A. heterophylla are larger, with a "swollen body to one cm thick." The four cotyledons on seedlings are also wider, 3 to 5 mm compared with 1.5 for A. columnaris.

• Buck, Michael G. and Roger H. Imotos. 1982. "Growth of 11 Introduced Tree Species on Selected Forest Sites in Hawaii." Pacific Southwest Forest & Range Experiment Station Research Paper PSW-169. Forest Service, U.S. Department of Agriculture. 12p.

• Little, E.L., Jr., and R.G. Scolmen. 1989. Common Forest Trees of Hawaii. Agriculture Handbook No. 679. Forest Service, U.S. Department of Agriculture.

• Scowcroft, Paul G. 1988. "Germinabiliy of Cook Pine (Araucaria columnaris) Seeds under Different Storage Conditions." USDA Forest Service, Pacific Southwest Forest and Range Experiment Station, Institute of Pacific Islands Forestry, Honolulu, Hi.
  Cook and Norfolk Island Pines in the Palomar College Arboretum

  Cook Pine (Araucaria columnaris)

  Norfolk Island Pine (Araucaria heterophylla)

  Cook Pine (Araucaria columnaris)

  Norfolk Island Pine (Araucaria heterophylla)

  The bark of the Cook pine exfoliates into larger flakes (red arrow).
  In the Norfolk island pine the bark typically peels into slender rolls.

  In general, the interval between tiers of limbs is greater on the Norfolk Island pine, particularly on younger trees. In addition, the horizonal limbs are longer than those of the Cook pine. The Cook pine has a slender, spire-like crown with shorter, more closely-spaced horizontal branches. Throughout southern California, there are trees with branching intermediate between the two previous species. The leaf shape and size is variable and not very useful in separating these two species. Some authors have suggested that the bark of cook pine exfoliates into larger flakes. This appears to hold true in the Palomar College Arboretum; however, I have seen trees with intermediate bark flakes. In fact, trees in southern California with intermediate characteristics between the two species may be hybrids.

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  Cook pines (Araucaria columnaris) in Encinitas, California
  
  

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  Strikingly Different Cook & Norfolk Island Pines in San Marcos
  

  Left: Cook pine (Araucaria columnaris). Right: Norfolk island pine (A. heterophylla). Photo taken in residential neighborhood west of Palomar College. Note Owens Peak (Palomar "P" Mountain) in the distance. It would be difficult to classify these as the same species.

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  Phylogenetic studies comparing chloroplast DNA in the Araucariaceae show that the Norfolk Island pine's closest relatives are a clade of 13 species of Araucaria endemic to New Caledonia, including the Cook pine (A. columnaris). See: American Journal of Botany Vol. 85 ( No. 11): 1507-1516, 1998. Although New Caledonia is a relatively small island of only 19,000 square kilometers, it contains a rich conifer flora of 43 endemic species. In fact, 13 of the 19 species of Araucaria and five of the 13 species of Agathis are endemic to this island. Other rich conifer areas include New Zealand and the Sichuan Province of Western China. California is also a rich conifer region with 33 species in the pine family (Pinaceae), 2 species in the yew family (Taxaceae), 2 species in the redwood family (Taxodiaceae), and 16 species in the cypress family (Cupressaceae). In fact, 20 of the more than 100 pine species (Pinus) on earth are native to California.

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  Araucariaceae In Palomar College Arboretum Pinaceae In The Palomar College Arboretum

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