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''Alstonia'' is a widespread genus of evergreen trees and shrubs, of the dogbane plant family Apocynaceae. It was named by Robert Brown in 1811, after Charles Alston (1685–1760), Professor of botany at Edinburgh from 1716-1760. The type species ''Alstonia scholaris'' (L.) R.Br. was originally named ''Echites scholaris'' by Linnaeus in 1767. ==Description== ''Alstonia'' consists of about 40-60 species (according to different authors), native to tropical and subtropical Africa, Central America, southeast Asia, Polynesia and Australia, with most species in the Malesian region. These trees can grow very large, such as ''Alstonia pneumatophora'', recorded with a height of 60 m and a diameter of more than 2 m. ''Alstonia longifolia'' is the only species growing in Central America (mainly shrubs, but also trees 20 m high). The leathery, sessile, simple leaves are elliptical, ovate, linear or lanceolate and wedge-shaped at the base. The leaf blade is dorsiventral, medium-sized to large and disposed oppositely or in a whorl and with entire margin. The leaf venation is pinnate, with numerous veins ending in a marginal vein. The inflorescence is terminal or axillary, consisting of thyrsiform cymes or compound umbels. The small, more or less fragrant flowers are white, yellow, pink or green and funnel-shaped, growing on a pedicel and subtended by bracts. They consist of 5 petals and 5 sepals, arranged in four whorls. The fertile flowers are hermaphrodite. The gamosepalous green sepals consist of ovate lobes, and are distributed in one whorl. The annular disk is hypogynous. The five gamesepalous petals have oblong or ovate lobes and are disposed in one whorl. The corolla lobes overlapping to the left (such as ''A. rostrata'') or to the right (such as ''A. macrophylla'') in the bud. The ovary has 2 separate follicles with glabrous or ciliate, oblong seeds that develop into deep blue podlike, schizocarp fruit, between 7–40 cm long. The plants contain a milky latex, rich in poisonous alkaloids. The ''Alstonia macrophylla'' is commonly known in Sri Lanka as 'Havari nuga' or the 'wig banyan' because of its distinct flower that looks like a woman's long wig. ''Alstonia'' trees are used in traditional medicine. The bark of the ''Alstonia constricta'' and the ''Alstonia scholaris'' is a source of a remedy against malaria, toothache, rheumatism and snake bites. The latex is used in treating coughs, throat sores and fever. Many ''Alstonia'' species are commercial timbers, called ''pule'' or ''pulai'' in Indonesia and Malaysia. Trees from the section ''Alstonia'' produce light timber, while those from the sections ''Monuraspermum'' and ''Dissuraspermum'' produce heavy timber. ''Alstonia'' trees are widespread and mostly not endangered. However a few species are very rare, such as ''A. annamensis'', ''A. beatricis'', ''A. breviloba'', ''A. stenophylla'' and ''A. guangxiensis''. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Alstonia」の詳細全文を読む スポンサード リンク
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