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''Erigeron maniopotamicus'' is a rare species of flowering plant in the aster family known by the common name Mad River fleabane.〔 It is endemic to northwestern California, where it is known from only four locations in Humboldt and Trinity Counties.〔(The Nature Conservancy )〕〔(California Native Plant Society Rare Plant Profile )〕〔(Calflora taxon report, University of California, ''Erigeron maniopotamicus'' G.L. Nesom and T.W. Nelson Mad River fleabane )〕 ''Erigeron maniopotamicus'' grows in open areas in forest, woodland, and meadow habitat along the path of the Mad River, generally in barren areas without much plant cover. The soils are rocky and tan in color and occur near areas of serpentine soils, but the plant does not occur on the serpentine soil.〔Nesom, G. L. and T. W. Nelson. (2004). (A new species of ''Erigeron'' (Asteraceae: Astereae) from northwestern California. Sida'' 21:2 673-78 ) .〕 ''Erigeron maniopotamicus'' was described to science in 2004 from a type specimen collected on Board Camp Mountain in Humboldt County in California.〔Nesom, G. L. and T. W. Nelson. (2004). (A new species of ''Erigeron'' (Asteraceae: Astereae) from northwestern California. Sida 21:2 673-78. ) includes photo of isotype herbarium specimen on page 674 and keys distinguishing this from related species on pages 677-678〕 The authors named the plant after the Mad River, choosing an epithet derived from Greek words meaning word "mad river", using the British definition of the word "mad," corresponding to the American term "crazy."〔 ''Erigeron maniopotamicus'' is a perennial herb growing from a taproot and caudex unit. The stem is up to 27 centimeters (11 inches) tall and has a coating of rough hairs. The leaves are hairy, lance-shaped, and up to 10 centimeters (4 inches) long by 1.4 cm (0.6 inches) wide. The stem and leaves are green or purple-tinged. The inflorescence is a single flower head or a cluster of up to 4 heads. Each head has a lining of pointed phyllaries which are green with orange midnerves. It contains up to 33 white, pinkish, or purple ray florets each about a centimeter (0.4 inches) long, surrounding numerous yellow disc florets.〔〔(Flora of North America, ''Erigeron maniopotamicus'' G. L. Nesom & T. W. Nelson, 2004. Mad River fleabane )〕 Potential threats to the species include grazing of cattle, logging, and activity related to the logging industry including construction, maintenance of roads, and dumping.〔〔 ==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「Erigeron maniopotamicus」の詳細全文を読む スポンサード リンク
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