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''Cirsium douglasii'' is a species of thistle known by the common names Douglas' thistle and California swamp thistle. It is native to the central coast and northern California ranges, foothills, and plateaus, and adjacent parts of southern Oregon and northwest Nevada.〔(Biota of North America Program 2014 county distribution map )〕 It grows in wet places in a number of types of habitat.〔(Calflora taxon report, University of California, ''Cirsium douglasii'' DC., Douglas' thistle, swamp thistle )〕 ==Description== This native thistle, ''Cirsium douglasii'', is a biennial or short-lived perennial herb growing up to tall, with a branching woolly stem. The longest gray-tomentose leaves, located about the base of the plant, are up to long. They are sometimes lobed or toothed and are borne on a spiny petiole.〔(Flora of North America: ''Cirsium douglasii'' )〕 The inflorescence is a cluster of several flower heads surrounded by small leaves. Each flower head is up to long and lined with purple-tipped spiny phyllaries. The head contains purple or white flowers. The fruit is a dark-colored achene long/diameter with a pappus which may reach in length.〔 ;Varieties〔 * ''Cirsium douglasii'' var. ''breweri'' (A.Gray) D.J.Keil & C.E.Turner - California, Oregon, Nevada * ''Cirsium douglasii'' var. ''douglasii'' - California 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「Cirsium douglasii」の詳細全文を読む スポンサード リンク
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