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''Pellaea glabella'' is the smooth cliffbrake. For much of pteridological history, it was regarded as a reduced form or variety of ''Pellaea atropurpurea''. ''P. glabella'' is known to exist in two cryptic species, one diploid and one tetraploid. The diploid reproduces sexually, while the tetraploid is normally apogamous. It is now known that the tetraploid form of the species is one of the parents of the original hybrid ''P. Xatropurpurea'' that became the apogamous species. ''P. glabella'' is epipetric, normally growing on well-weathered limestone. It favors more exposed sites than ''P. atropurpurea''. This species is distinguished by its sessile or nearly sessile pinnae and smooth, not hairy, stipes. ''P. glabella'' has been assigned a total of four subspecies: * ''Pellaea glabella'' subsp. ''glabella'' Mettenius ex Kuhn * ''Pellaea glabella'' subsp. ''missouriensis'' (G. J. Gastony) Windham * ''Pellaea glabella'' subsp. ''occidentalis'' (E. E. Nelson) Windham * ''Pellaea glabella'' subsp. ''simplex'' (Butters) A. Löve & D. Löve The subspecies ''glabella'' and ''simplex'' are the tetraploids, while ''missouriensis'' and ''occidentalis'' are the diploids. ''Glabella'' and ''missouriensis'' have hairlike scales near the midrib, while ''simplex'' and ''occidentalis'' are completely glabrous. ==References== *''P. glabella'' USDA Plants Profile: http://plants.usda.gov/java/profile?symbol=PEGL *''P. glabella'' in Flora of North America: http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=233500875 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「Pellaea glabella」の詳細全文を読む スポンサード リンク
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