In this treatment there are 20 species (for decades it was 19, with a new species from New Caledonia described in 2017). The extant species of the genus have been assigned to 4 sections as follows (Wilde and Eames 1952):
Sect. Araucaria (syn: Colymbea):
A. cunninghamii, A. heterophylla, and the 14 New Caledonian endemics: A. bernieri, A. biramulata, A. columnaris, A. goroensis, A. humboldtensis, A. laubenfelsii, A. luxurians, A. montana, A. muelleri, A. nemorosa, A. rulei, A. schmidii, A. scopulorum and A. subulata.
Besides these, Ohsawa et al. (1995) have also described one extinct section, Yezonia, containing one extinct species (A. vulgaris) from the Cretaceous of northern Japan (many extinct species have been described in the other sections as well). Although these sections were defined largely on the basis of morphological data, an analysis of the rbcL gene from chlorplast DNA of 29 Araucariaceae species generally confirmed that the extant sections are representative of phylogenetic divisions of the genus (Setoguchi et al. 1998). This study also found that the species of Section Eutacta, endemic to New Caledonia, shared nearly identical rbcL sequences (homology values of 99.5% to 100%; 100% in 10 of the species), suggesting relatively recent and rapid adaptive radiation, probably driven by the island's extraordinary edaphic conditions, i.e., ultramafic soils. See the Remarks section for more information.
Syn.: Eutassa Salisb. (applied only to the species of Section Eutacta).
Evergreen, mostly dioecious trees with regularly whorled branches. Buds inconspicuous. Young trees branched to the ground, old trees with a long clear bole and flattened crown. Juvenile leaves needle-like, thin, loosely imbricate, spirally arranged. Adult leaves usually scale-like or sometimes needle-like, spirally arranged or nearly 2-ranked, usually closely imbricate, overlapping, flattened, sometimes lanceolate and sharp-pointed, persistent for many years, often with faint stomata above. Male cones terminal and solitary or disposed in clusters, with numerous spirally arranged stamens, anthers 6-8 celled. Female cones globose, ripening in 2-3 years, heavy, milky; scales usually with thin spiny apical umbos, scales thin and somewhat flattened, cones dehiscent at maturity; ovules one per scale. Ovules and seeds united with the scale. Seeds usually winged on the edges, sometimes edible. Cotyledons 2-4. Germination with epigeal or hypogeal cotyledons (Silba 1986).
Araucaria has a highly disjunct distribution: Chile, Argentina, southern Brazil, New Caledonia, Norfolk Island, Australia, and New Guinea. Some authors regard its occurrence in South America as the result of a vicariance event, but considering the ancient lineage of the family and its former abundance in the Northern Hemisphere, its extant distribution is likely relictual (Setoguchi et al. 1998).
I have heard that A. araucana may exceed 1000 years. There are no data for most species, but A. araucana is also distinctive within the genus in occupying relatively dry habitats, which are typical for most extremely old conifers.
Many species, due to their large size, are or have been important sources of timber. Examples include A. angustifolia, A. araucana, A. bidwillii, A. cunninghamii and A. hunsteinii. The nutritious and large seeds of A. bidwillii were an important food source for aboriginal peoples and are now an Australian delicacy.
Some of the more impressive (large) species are popular ornamentals, widely planted in warm temperate and subtropical regions. Quite a few species may be seen in many warm temperate or tropical botanical gardens. Species native to temperate and subtropical regions in Chile, Argentina, Brazil, and Australia have been preserved in some public parks or forest preserves, where they may be found in their natural habitat. However, many of the tropical species, such as the 14 species endemic to New Caledonia and the Malesian species, have received limited protection, are difficult to locate in the wild, and are threatened with extinction. There is a trend toward recognizing the botanical significance of these tropical species and providing them with statutory protection, but at the same time their habitat is rapidly disappearing due to population and development pressures. Their fate is for the most part uncertain.
The genus is named after the province of Arauco in South Chile (Vidakovic 1991).
From Setoguchi et al. (1998): "New Caledonia, one of the continental islands, originated from a part of Gondwanaland and was separated from the continent between the Triassic and the end of the Jurassic. However, a large area of New Caledonia is covered with ultramafic soil derived from peridotite, and it is suggested that this area was formed at the end of the Eocene. Most of the species of Araucariaceae are distributed in this soil (12 of the 13 species in Araucaria and four of the five species in Agathis). Jaffre suggested that there was differentiation of new species of Araucaria in the post-Eocene, after the emplacement of peridotite. His discussion agrees with the findings of very low sequence divergence in the rbcL gene among endemics of Araucaria and Agathis. It is suggested that the adaptive radiation to new edaphic conditions, i.e., ultramafic soils, caused their rapid differentiation after the Eocene."
Abstract of Haines et al. (1984): "Pollination was studied in three species of Araucaria: A. cunninghamii, A. heterophylla and A. bidwillii. More limited observations were made for A. hunsteinii and A. angustifolia. The investigation revealed considerable variation among species of Araucaria with respect to pollination features. The bract scale of the receptive cone of both A. cunninghamii and A. heterophylla has a stoma-free furrow which directs pollen grains onto a thin flange on the tip of the ovuliferous scale. The bract scale of A. bidwillii bears stomata over most of its surface, and is broady scalloped so that pollen grains are deposited in a band across both bract and ovuliferous scales. On germination, the pollen tubes of these three species penetrate the epidermis of the scale and for a short distance grow beneath the surface before emerging and travelling, without branching or major deviation, towards the proximal end of the ovuliferous scale. Results are discussed in relation to pollination mechanisms in other conifers and to taxonomic divisions within the Araucariaceae."
Haines, R.J.; Prakash, N. and Nikles, D.G. 1984. Pollination in Araucaria Juss. Australian Journal of Botany 32(6): 583-594.
Hortus Botanicus Catinensis, URL = http://www.dipbot.unict.it/orto/0001-1.html.
Ohsawa, T., H. Nishida and M. Nishida. 1995. Yezonia, a new section of Araucaria (Araucariaceae) based on permineralized vegetative and reproductive organs of A. vulgaris comb. nov. from the upper Cretaceous of Hokkaido, Japan. Journal of Plant Research 108: 25-39.
[Anonymous, undated]. Pinheiro-do-Paraná, http://www.pr.gov.br/seec/pinheiro/index.html (accessed 2000.06.23, now defunct).
Wilde, M.H. and A. J. Eames. 1952. The ovule and seed of Araucaria bidwilli with discussion of the taxonomy of the genus. II. Taxonomy. Annals of Botany New Series 16: 27-47.
Bose, M.N. 1975. Araucaria haastii Ettingshausen from Shag Point, New Zealand. Palaeobotanist 22: 76-80.
Escapa, I. H. and S. A. Catalano. 2013. Phylogenetic analysis of Araucariaceae: integrating molecules, morphology and fossils. Int. J. Plant Sci. 174(8):1153-1170.
Hollingsworth, P. 2006. RBGE - Research Into Endemic Conifers of New Caledonia. http://rbg-web2.rbge.org.uk/Araucaria/ (accessed 2006.03.08). This is a clearinghouse web page with access to a variety of information on active research the Royal Botanic Garden Edinburgh is doing on Araucaria of New Caledonia.
Stockey, R.A. 1975. Seeds and embryos of Araucaria mirabilis. American Journal of Botany 62: 856-868.
Stockey, R.A. 1978. Reproductive biology of Cerro Cuadrado fossil conifers: Ontogeny and reproductive strategies in Araucaria mirabilis (Spegazzini) Windhausen. Palaeontographica B 166: 1-15.
Stockey, R.A. 1980a. Anatomy and morphology of Araucaria sphaerocarpa Carruthers from the Jurassic inferior Oolite of Bruton, Somerset. Botanical Gazette 141: 116-124.
Stockey, R.A. and H. Ko. 1986. Cuticle micromorphology of Araucaria de Jussieu. Botanical Gazette 147: 508-548.
Stockey, R.A., M. Nishida, and H. Nishida. 1992. Upper Cretaceous araucarian cones from Hokkaido: Araucaria nihongii sp. nov. Review of Palaeobotany and Palynology 72: 27-40.
Stockey, R.A., M. Nishida, and H. Nishida. 1994. Upper Cretaceous araucarian cones from Hokkaido and Saghalien: Araucaria nipponensis sp. nov. International Journal of Plant Science 155: 800-809.
Veillon, J.-M. 1978. Architecture of the New Caledonian species of Araucaria. P. 233-245 in P.B. Tomlinson and M.H. Zimmermann [eds.], Tropical trees as living systems. Cambridge University Press, Cambridge.
Veillon, J.-M. 1980. Architecture des especes neo-caledoniennes du genre Araucaria. Candollea 35: 609-640.
Last Modified 2017-12-29