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Dennstaedtiaceae is one of fifteen families in the order Polypodiales, the most derived families within monilophytes (ferns). It includes the world's most abundant fern, ''Pteridium aquilinum'' (bracken). Members of the order generally have large, highly divided leaves and have either small, round intramarginal sori with cup-shaped indusia (e.g. ''Dennstaedtia'') or linear marginal sori with a false indusium formed from the reflexed leaf margin (e.g. ''Pteridium''). The morphological diversity among members of the order has confused past taxonomy, but recent molecular studies have supported the monophyly of the order and the family.〔Smith, A. R., K. M. Pryer, et al. (2006). "A classification for extant ferns." Taxon 55(3): 705-731〕 The reclassification of Dennstaedtiaceae and the rest of the monilophytes was published in 2006,〔 so most of the available literature is not updated. ==Characteristics== * Terrestrial or scrambling over other vegetation—scandent * Rhizomes long-creeping, occasionally short-creeping * Rhizomes bear jointed hairs * Rhizomes often siphonostelic or polystelic * Petioles often with epipetiolar buds * Petioles usually with gutter-shaped vascular strand (open end adaxial) * Petiole pubescent of glabros * Blades often large * Blades often 2-3 pinnate, can be 1-4 pinnate or more divided * Inducement of hairs, no scales * Veins free, or forked, or pinnate, rarely vanishing * Sori near the margin, or submarginal, sometimes fused with the blade to form a cup or pouch or obscured in a recurved portion of the blade margin * Sori mostly linear, may be discrete * Indusia linear or cup shaped at blade margin, or reflexed over sori * Sporangium stalk with 1-3 rows of cells * Spore tetrahedral and trilete, or reniform and monolete * Gametophyte green, cordate Characteristics described by Smith et al., and Judd et al.〔〔Judd, W. S., C. C. Campbell, et al. (2008). Plant Systematics: A Phylogenetic Approach. Sunderland, Ma, Sinauer Associates, Inc〕 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「Dennstaedtiaceae」の詳細全文を読む スポンサード リンク
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