Often ±dioecious (unique among our spp.); lvs 6-20 cm נ0.3-0.7 mm, erect, twisted, whitish or pale reddish-brown toward the base, with abundant stomates and 4 or more peripheral strands; sporangia oblong, 6-10(-14) mm, to one-half covered by the velum, marked with fine brown lines at maturity; megaspores (0.4-)0.5-0.65 mm wide, low-tuberculate or nearly smooth; 2n=22. Terrestrial on thin, seasonally wet soil, mostly over limestone; sc. Ky. to nw. Ga., w. to Ark. and e. Kans.

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

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