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''Platanthera flava'', the palegreen orchid, is a species of pale-flowered orchid. It is native to eastern North America, from Texas east to Florida, north to Ontario, Quebec and Nova Scotia.〔(Flora of North America v 26 p 563, ''Platanthera flava'' )〕〔(Biota of North America Program, county distribution map )〕 ''Platanthera flava'' has from 10-40 flowers in an inflorescence. In the north of its range, in Canada, this species is particularly associated with shorelines of lakes and rivers, in the seasonally flooded zone.〔Reddoch, J. and Reddoch, A. (1997). The Orchids in the Ottawa district. Canadian Field-Naturalist, 111, 1–185.〕 In Nova Scotia, it occurs in wet meadows on seasonally flooded shorelines with rare shoreline species such as Plymouth Gentian.〔Keddy, P.A. 1985. Lakeshore plants in the Tusket River Valley, Nova Scotia: the distribution and status of some rare species including ''Coreopsis rosea'' and ''Sabatia kennedyana''. Rhodora 87:309-320.〕 In the south, such as in Texas, it is found in wet savannas and flatwoods.〔Liggio, J. and Liggio, A.O. 1999. Wild Orchids of Texas. University of Texas Press, Austin. p.139-141.〕 The shoreline habitats of the north are maintained by ice scour, while in the south, the flatwoods are maintained by recurring fire. Hence, it appears that this species depends upon recurring natural disturbance to maintain open sunny conditions. ==Varieties== Two varieties are recognized: *''Platanthera flava'' var. ''flava'' - southern part of species range *''Platanthera flava'' var. ''herbiola'' (R. Brown) Luer - northern part of species range 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「Platanthera flava」の詳細全文を読む スポンサード リンク
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