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''Silphium integrifolium'' is a species of flowering plant in the aster family, Asteraceae. Its common names include whole-leaf rosinweed, entire-leaf rosinweed, and prairie rosinweed.〔(''Silphium integrifolium''. ) NatureServe. 2012.〕 It is native to eastern North America, including Ontario in Canada and the eastern and central United States as far west as New Mexico.〔(''Silphium integrifolium''. ) Germplasm Resources Information Network (GRIN).〕 ==Description== This species is a perennial herb growing from a fibrous root system and producing stems up to 2 meters tall.〔(''Silphium integrifolium''. ) Flora of North America.〕 It can form a large clump of up to 100 stems.〔Fay, P. and D. C. Hartnett. (1991). (Constraints on growth and allocation patterns of ''Silphium integrifolium'' (Asteraceae) caused by a cynipid gall wasp. ) ''Oecologia'' 88(2), 243-50.〕 The stems are hairless to slightly rough-haired, and sometimes waxy in texture. The leaves are oppositely arranged on the stems. The basal leaves are lost by maturity. The leaf blades are lance-shaped to ovate, smooth-edged or toothed, hairless to rough-haired, and up to about 23 centimeters long.〔 The inflorescence holds one to 15 flower heads.〔 The head is lined with 2 or 3 rows of phyllaries which are hairless or rough and sometimes glandular. The head has up to 36 yellow ray florets and many yellow disc florets. The fruit has a short pappus.〔 There are two varieties of the species:〔 *''S. integifolium'' var. ''integrifolium'' – 40 centimeters to 2 meters in height *''S. integifolium'' var. ''laeve'' – generally 1 to 1.5 meters tall, with more florets and hairless leaves 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「Silphium integrifolium」の詳細全文を読む スポンサード リンク
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