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Araucariaceae
Henkel & W. Hochst. (1865)Common NamesAraucaria family.Taxonomic notesThree genera with about 40 species. Some authors elevate the family to the level of an order, Araucariales Heintze (1927).DescriptionEvergreen trees with spirally arranged, narrow or broad leaves often with parallel veins. Dioecious or monoecious. Male cones relatively large, cylindrical, with numerous sporophylls and with ±12 inverted pollen sacs; pollen grains wingless. Female cone usually borne erect, subglobose to ovoid, maturing in two years, relatively large and milky, falling upon maturity; scales one-seeded, without distinct bracts. Cotyledons 4, often fused into 2 double cotyledons (1).RangePrimarily the southern hemisphere.Big TreeProbably Agathis australis.OldestThere are credible reports of Agathis australis and Araucaria araucana exceeding 1000 years.DendrochronologyLimited studies on most of the temperate Australian and New Zealand species.EthnobotanySome species are important timber trees. Most species of Agathis, for example, are among the largest trees known in the areas where they grow, and those species of Araucaria not native to New Caledonia also reach prodigious size. They have been principal species of concern for logging operations in Australia, New Zealand, and many parts of Malesia. Consequently, many of the finest stands of these species have been logged, and many of the species are threatened or endangered (3). Some species, notably Araucaria bidwillii, are also an important food source.ObservationsThe Araucariaceae include several hardy and attractive species that are very widely used as ornamentals, including Araucaria angustifolia, A. araucana, A. bidwillii and A. heterophylla. These are found in hundreds of botanic gardens and arboreta, and in fact A. heterophylla can be found in even the coldest climate thanks to its popularity as an indoor house plant. Conversely, most of the remaining species of the family are tropical and are not widely known outside of their native ranges. In many cases those ranges are relatively large and the trees fairly easy to locate, but several taxa including Wollemia nobilis, several New Caledonian species of Araucaria, and several Malesian species of Agathis are narrow endemics, threatened by habitat loss.Remarks"The Southern Hemisphere conifer family Araucariaceae has a very restricted present day distribution, but was more widespread in the past. The genus Araucaria is represented by good fossil material in both hemispheres as early as the Jurassic, while Agathis is only known from the Southern Hemisphere beginning in the Cretaceous. Cuticle studies of extant araucarians have enabled accurate comparisons of fossil leaves to living taxa. Araucaria Section Bunya is represented by cones of several types in the Jurassic. In addition to these remains, a suite of araucarian cones showing affinities to several sections of the genus Araucaria have been described from England, Japan and North America" (4).Citations(1) Silba 1986.(2) Vidakovic 1991. (3) World Conservation Monitoring Centre - Trees. (4) Stockey, Ruth A.1994. Mesozoic araucariaceae: Morphology and systematic relationships. Journal of Plant Research 107(1088):493-502. ABSTRACT: The Southern Hemisphere conifer family Araucariaceae has a very restricted present day distribution, but was more widespread in the past. The genus Araucaria is represented by good fossil material in both hemispheres as early as the Jurassic, while Agathis is only known from the Southern Hemisphere beginning in the Cretaceous. Cuticle studies of extant araucarians have enabled accurate comparisons of fossil leaves to living taxa. Araucaria Section Bunya is represented by cones of several types in the Jurassic. In addition to these remains, a suite of araucarian cones showing affinities to several sections of the genus Araucaria have been described from England, Japan and North America. Evidence that fossil araucarian cones may have produced seeds with hypogeal germination is discussed in light of recent work on germination of extant bunya seedlings and the discovery of new fossil shoots from the Jurassic Morrison Formation of Utah. | |
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