南洋杉属属

南洋杉化石广泛分布于全球，但现仅原生于南半球。当中大部分现存物种为新喀里多尼亚特有，应为对当地富重金属土壤辐射适应之结果。

古生物学分析指，南洋杉和蜥脚亚目恐龙的多样性同时于晚侏罗世至早白垩世达至颠峰。蜥脚类似乎以南洋杉为主食，推动后者演化出更高树冠之避之，再诱使蜥脚类演化出更长颈以适应之。

Araucaria (; original pronunciation: [a.ɾawˈka. ɾja]) is a genus of evergreen coniferous trees in the family Araucariaceae. While today they are largely confined to the Southern Hemisphere, during the Jurassic and Cretaceous they were globally distributed. There are 20 extant species in New Caledonia (where 14 species are endemic, see New Caledonian Araucaria), eastern Australia (including Norfolk Island), New Guinea, Argentina, Brazil, Chile and Uruguay.

The genus is familiar to many people as the genus of the distinctive Chilean pine or monkey-puzzle tree (Araucaria araucana). No distinct vernacular name exists for the genus. Many are called "pine", such as the "Norfolk pine" (Araucaria heterophylla) although they are only distantly related to true pines, in the genus Pinus.

Description

Araucaria are mainly large trees with a massive erect stem, reaching a height of 5–80 metres (16–262 ft). The horizontal, spreading branches grow in whorls and are covered with leathery or needle-like leaves. In some species, the leaves are narrow, awl-shaped, and lanceolate, barely overlapping each other; in others, they are broad and flat, and overlap broadly.

The two South American species A. angustifolia and A. araucana are mostly dioecious, with male and female cones found on separate trees. The other species in the genus are monoecious. The female cones, on the top of the tree, are globose, and vary in size among species from 7 to 25 centimetres (3 to 10 in) in diameter. They contain 80–200 large edible seeds, similar to pine nuts, though larger. The male cones are smaller, 4–10 cm (1+1⁄2–4 in) long, narrow to broad cylindrical, and 1.5–5 cm (1⁄2–2 in) broad.

Taxonomy

The genus is named after the Spanish exonym Araucano ("from Arauco") applied to the Mapuche of south-central Chile and south-west Argentina, whose territory incorporates natural stands of a species in this genus identified as A. araucana; the Mapuche people call it pewen, and consider it sacred. Some Mapuche living in the Andes name themselves Pewenche ("people of the pewen") as they traditionally harvested the seeds extensively for food.

There are four extant sections and two extinct sections in the genus, sometimes treated as separate genera.

Genetic studies

Genetic studies indicate that the extant members of the genus can be subdivided into two large clades – the first consisting of the sections Araucaria, Bunya, and Intermedia; and the second of the strongly monophyletic section Eutacta. Sections Eutacta and Bunya are both the oldest taxa of the genus, with Eutacta possibly older.

Taxa marked with † are extinct.

Distribution and paleoecology

Members of Araucaria are found in Argentina, Brazil, New Caledonia, Norfolk Island, Australia, New Guinea, Chile and Papua (Indonesia). Many if not all current populations are relicts, and of restricted distribution. They are found in forest and maquis shrubland, with an affinity for exposed sites. The earliest records of the genus date to the Middle Jurassic, represented by Araucaria mirabilis of Argentina, and Araucaria sphaerocarpa from England. Fossil records show that the genus also formerly occurred in the northern hemisphere until the end of the Cretaceous period. A possible species of Araucaria may have existed in New Zealand as recently as 350,000 years ago. However, it is also possible that this fossil actually represents a specimen of Agathis. By far the greatest diversity exists in New Caledonia, likely due to a relatively recent adaptive radiation, as all New Caledonian species are more closely related to each other than they are to other Araucaria.

Uses

Some of the species are relatively common in cultivation because of their distinctive, formal symmetrical growth habit. Several species are economically important for timber production.

In addition to timber, they are grown for ornamental purposes. Several species are considered threatened/endangered.

Food

The edible large seeds of A. araucana, A. angustifolia and A. bidwillii — also known as Araucaria nuts, and often called, although improperly, pine nuts — are eaten as food, particularly among the Mapuche people of Chile and southwest Argentina, the Kaingang people in Southern Brazil and among Indigenous Australians.

In South America, Araucaria nuts or seeds are called piñas or piñones in Spanish and pinhões in Portuguese, like pine nuts in Europe.

Pharmacological activity

Pharmacological reports on the genus Araucaria are anti-ulcer, antiviral, neuro-protective, anti-depressant and anti-coagulant.