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''Arctium'' is a genus of biennial plants commonly known as the thistle burdock, family Asteraceae.〔(Linnaeus, Carl von. 1753. Species Plantarum 2: 816 )〕 Native to the Old World, several species have been widely introduced worldwide.〔(【引用サイトリンク】 Arctium )〕 ==Description== Plants of the genus ''Arctium'' have dark green leaves that can grow up to 28" (71 cm) long. They are generally large, coarse and ovate, with the lower ones being heart-shaped. They are woolly underneath. The leafstalks are generally hollow. ''Arctium'' species generally flower from July through to October. Burdock flowers provide essential pollen and nectar for honeybees around August when clover is on the wane and before the goldenrod starts to bloom. The roots of burdock, among other plants, are eaten by the larva of the Ghost Moth (''Hepialus humuli''). The plant is used as a food plant by other Lepidoptera including Brown-tail, ''Coleophora paripennella'', ''Coleophora peribenanderi'', the Gothic, Lime-speck Pug and Scalloped Hazel. The prickly heads of these plants (burrs) are noted for easily catching on to fur and clothing. In England, some birdwatchers have reported that birds have become entangled in the burrs leading to a slow death, as they are unable to free themselves. Burdock's clinging properties, in addition to thus providing an excellent mechanism for seed dispersal,〔 led to the invention of Velcro. A large number of species have been placed in genus ''Arctium'' at one time or another, but most of them are now classified in the related genus ''Cousinia''. The precise limits between ''Arctium'' and ''Cousinia'' are hard to define; there is an exact correlation between their molecular phylogeny. The burdocks are sometimes confused with the cockleburs (genus ''Xanthium'') and rhubarb (genus ''Rheum''). 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「Arctium」の詳細全文を読む スポンサード リンク
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