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Helianthus grosseserratus, commonly known as sawtooth sunflower or thick-tooth sunflower〔 〕 , is a perennial sunflower in the family Asteraceae, with a large flowering head (inflorescence). The plant may reach 3–12 feet (91–366 cm) in height and is found along streams, damp prairies and roadsides in the eastern and central parts of Canada and the USA, primarily in the northern Great Plains and Great Lakes Region, with additional populations as far as Maine, Georgia, and Texas.〔〔(Biota of North America Program 2014 county distribution map )〕 It prefers full sun and moist, fertile loamy soil with high organic content.〔(【引用サイトリンク】title=Illinois Wildflowers, Sawtooth Sunflower (''Helianthus grosseserratus''): ) 〕 The lanceolate leaves are simple and alternate and may reach 4 to 12 inches (10–30 cm) long and from 1 to 4 inches (2–10 cm) wide. The leaves have large teeth along the edges (hence the name, ''sawtooth'') to occasionally nearly entire and the tips are pointed.〔(Flora of North America, ''Helianthus grosseserratus'' M. Martens, 1839. Sawtooth sunflower, hélianthe à grosses dents )〕 The head (formally composite flower) is 3 to 4 inches (7–10 cm) wide with golden-yellow disk flowers that bloom in summer and autumn. The 10-20 yellow ray florets are about 1.5 inches (3.81 cm) long. The fruit is a single achene within a husk.〔 Various insects, birds and mammals (including cattle) feed on either the plant or its seeds.〔〔(【引用サイトリンク】title=Kansas Wildflowers and Grasses - Sawtooth sunflower: ) 〕 Native Americans used to treat burns with a poultice made from the flowers.〔 ==References== 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「Helianthus grosseserratus」の詳細全文を読む スポンサード リンク
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