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''Polygonum ramosissimum'' is a North American species of herbaceous annual plants in the buckwheat family,〔(''Polygonum ramosissimum'' ) United States Department of Agriculture plants profile, retrieved 14 July 2008〕 widespread across much of Canada and the United States, were it is commonly called Bushy knotweed.〔(Biota of North America Program 2014 state-level distribution map )〕 ==Description== ''Polygonum ramosissimum'' has erect stems growing (sometimes to 200 cm or 80 inches) tall, with yellowish-green to blue-green foliage. The stems are freely branched with closed flowers produced in groups of (1) 2 to 3(5) flowers in the upper ocreae of racemes that are up to long, the inflorescences are spike-like. The greenish-yellow, rarely pink or white marked flowers, are on pedicels that are longer than the calyx. The calyx is around long and 5-parted with the outer three sepals longer than the inner sepals. The seeds are produced in fruits called achenes, which are egg-shaped, dark brown and around long. The achenes also have a smooth shiny surface. The late season achenes are larger, from 4 to 15 mm long.〔(Flora of North America, ''Polygonum ramosissimum'' Michaux, 1803. Bushy knotweed )〕 ;Subspecies〔〔 There are a number of forms and two subspecies, that vary in flower and foliage coloration. ''Polygonum ramosissimum'' has great morphological variability,〔 which is notable on the same plant, between flowers and fruits produced early in the blooming season verses those produced late in the season, plants also show great variation over geographical areas. The following names are widely recognized. *''Polygonum ramosissimum'' subsp. ''prolificum'' (Small) Costea & Tardif *''Polygonum ramosissimum'' subsp. ''ramosissimum'' In Maryland, the species is listed as endangered or extirpated from the state, in Pennsylvania it has been exterminated from the state, and New Hampshire lists it as threatened.〔 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「Polygonum ramosissimum」の詳細全文を読む スポンサード リンク
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