Monographs Details: Hypolepis
Authority: Mickel, John T. & Beitel, Joseph M. 1988. Pteridophyte Flora of Oaxaca, Mexico. Mem. New York Bot. Gard. 46: 1-580.
Description:Genus Description - Terrestrial, thicket-forming; rhizome long-creeping, much-branched from the leaf bases, hairy; fronds mostly large, often scandent, bipinnate to quadripinnate, generally hairy, rarely glabrous; stipe stramineous, atropurpureous or castaneous, hairy to glabrous, spiny or not; lamina herbaceous to coriaceous, glabrous to hairy; veins free; sori marginal (to rarely medial, not in ours), round to oblong, generally protected by differentiated indusial flap or recurved tooth, without paraphyses, inner indusium lacking; spores bilateral, tuberculate to spinulose, perispore lacking.
Discussion:Type: Hypolepis tenuifolia (Forster) Bemhardi [=Lonchitis tenuifolia Forster].
Hypolepis is a pantropical genus of about 45 species, with 15-20 in America. It is most closely allied to Paesia (x = 26) and Pteridium (x = 52). Counts of n = 29 in H. nigrescens reflect an ancient link of an aneuploid series from 26 to 29 and the doubling of 26 to make the more common n = 52. The species with n=29 are a natural group (emarginate segments, recurved spines) and may deserve subgeneric segregation.
Hypolepis is distinguished by the surficial, long-creeping, hairy rhizome, discrete sori, and bilateral spores.
References: Brownsey, P. J. 1983. Polyploidy and aneuploidy in Hypolepis, and the evolution of the Dennstaedtiales. Amer. Fem J. 73: 97—108; Mickel, J. T. 1973. The phylogenetic position of and the classification within the Dennstaedtiaceae. J. Linn. Soc., Bot. 67:135-144.