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Senecioneae is the largest tribe of the Asteraceae, or the sunflower family, comprising approximately 150 genera and 3,000 species. Almost one-third of the species in this tribe are placed in the genus ''Senecio''. Its members exhibit probably the widest possible range of form to be found anywhere in the entire plant kingdom and include annuals, minute creeping alpines, perennial herbs, shrubs, climbers, succulents, trees and semi-aquatic plants. Plants in this tribe are responsible for more livestock poisonings than all other plants combined. The poisons are particularly pyrrolizidine alkaloids in ''Senecio''〔 and furanoeremophilanes in ''Tetradymia''.〔(【引用サイトリンク】 work = Flora of North America )〕 A number of species are well known in horticulture.〔 == Classification == Since the time of Bentham, the "premier systematic botanist of the nineteenth century" considerable efforts have been made to classify and understand the striking morphological diversity in Senecioneae.〔 The traditional view of the tribe has been that of one huge genus ''Senecio'' plus many other genera which exhibit varying degrees of distinctiveness.〔 Circumscription and delimitation of the tribe has experienced expansions and contractions over the decades as genera and groups of genera have been moved in and out,〔 as was the case for ''Arnica'', ''Liabum'', ''Munnozia'', ''Schistocarpha'', etc. which have since then been excluded.〔 Of the several potential causes for this constant redefinition the greatest is probably that little is known about its intergeneric relationships or a lack of phylogenetic understanding enhanced by the other problems of conflicting clues from morphological characters, the large size of the tribe, the absence of a precise delimitation or circumscription of ''Senecio''〔 and the naturalness of these assemblages combined with the imprecise boundaries of the different species themselves.〔 Many segregate genera have been recognized in recent studies, often with circumscriptions derived from selected representative species. It is yet unclear that the recognition of numerous segregate genera provides a better taxonomy than treating the variation patterns as infrageneric taxa. A respectable case can be made for maintaining ''Senecio'' as a broad concept, at least until revisionary studies at the species level are carried out and the results subjected to critical analyses.〔 Most genera that have been removed from Senecioneae in its broadest sense have come to rest within Liabeae or within a broadly circumscribed Heliantheae (e.g., allies in Arnicinae, Chaenactidinae, or Madiinae; ''Haploësthes'' in Flaveriinae; ''Raillardella'' and allies in Madiinae). Additional information may be found in B. G. Baldwin et al. (2002), H. Robinson (1981), B. Nordenstam (1977–1978) and K. Bremer (1994).〔 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「Senecioneae」の詳細全文を読む スポンサード リンク
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