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| image = Yew 1r.jpg | image_caption = ''Foliage and mature arils'' | regnum = Plantae | divisio = Pinophyta | classis = Pinopsida | ordo = Cupressales | familia = Taxaceae | familia_authority = S.F. Gray | subdivision_ranks = Genera | subdivision = *''Amentotaxus''-Catkin-Yew :(5 species) *''Austrotaxus''-New Calidonia Yew :(1 species) *''Cephalotaxus''-Plum Yew :(11 species) *''Diploporus'' *''Pseudotaxus''-White-berry Yew :(1 species) *''Sommerxylon'' *''Taxus'' -Common Yew :(about 11 species) *''Torreya''-Nutmeg Yew :(6 species) }} Taxaceae , commonly called the yew family, is a coniferous family which includes seven genera and about 30 species of plants, or in older interpretations three genera and 7 to 12 species. They are many-branched, small trees and shrubs. The leaves are evergreen, spirally arranged, often twisted at the base to appear 2-ranked. They are linear to lanceolate, and have pale green or white stomatal bands on the undersides. The plants are dioecious, rarely monoecious. The male cones are long, and shed pollen in the early spring. The female cones are highly reduced, with just one ovuliferous scale and one seed. As the seed matures, the ovuliferous scale develops into a fleshy aril partly enclosing the seed. The mature aril is brightly coloured, soft, juicy and sweet, and is eaten by birds which then disperse the hard seed undamaged in their droppings. However, the seeds are highly poisonous to humans, containing the poisons taxine and taxol.〔(Yew Poisoning: MedLine Plus Medical Encyclopedia )〕 ==Classification== Taxaceae is now generally included with all other conifers in the order Pinales, as DNA analysis has shown that the yews are monophyletic with the other families in the Pinales (Chase ''et al.'', 1993; Price, 2003), a conclusion supported by micromorphology studies (Anderson & Owens, 2003). Formerly they were often treated as distinct from other conifers by placing them in a separate order Taxales. Ernest Henry Wilson referred to Taxaceae as ''taxad'' in his book ”1916, Conifers and taxads of Japan".〔(taxad (plant family) ) : see Taxaceae; britannica〕 Some studies in the early 2000s suggested the genera ''Torreya'' and ''Amentotaxus'' were better transferred to Cephalotaxaceae, as genetic tests showed they are were more closely related to ''Cephalotaxus'' than to ''Taxus''. More recent studies have included, with ''Cephalotaxus'', in a broader interpretation of Taxaceae as a single larger family (Price, 2003). In this sense, the Taxaceae includes six genera and about 30 species. The differences suggested between Taxaceae and Cephalotaxaceae were based on the morphology of the seeds, with Taxaceae having smaller mature seeds growing to in 6-8 months and not being fully enclosed by the aril. Cephalotaxaceae seeds show a longer maturation period, ranging from 18-20 months, with the mature seeds fully enclosed in the aril and ranging from . A few botanists have transferred ''Austrotaxus'' to its own family, the Austrotaxaceae, suggesting it may be closer to the Podocarpaceae than to the other Taxaceae, but genetic evidence does not support this transfer. 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「Taxaceae」の詳細全文を読む スポンサード リンク
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