Monographs Details: Heterophyllium
Authority: Sharp, Aaron J., et al. 1994. The Moss Flora of Mexico. Part Two: Orthotrichales to Polytrichales. Mem. New York Bot. Gard. 69 (2)
Family:Sematophyllaceae
Scientific Name:Heterophyllium
Description:Genus Description - Plants moderately robust, in green, yellowish, or brownish, somewhat shiny, flat mats. Stems reddish, prostrate subpinnately branched; branches horizontally spreading, straight or curved, obscurely flattened; pseudoparaphyllia foliose. Stem and branch leaves ± differentiated (the stem leaves considerably larger and more acuminate), erect or erect-spreading and shghtiy complanate, ± secund, concave, lanceolate to ovate, long-acuminate; cells smooth, linear, yellowish, those at the insertion yellowish, those at the basal angles subquadrate and enlarged with thickened walls in several rows forming small but well-marked, concave, yellowish or red-brown alar groups. Perichaetial leaves distinctly differentiated, elongate. Setae elongate, smooth; capsules suberect or inclined, curved, cylindric; annulus ± differentiated; operculum apiculate or rostrate; exothecial cells not collenchymatous; exostome teeth lance-acuminate, with a zigzag median line, cross-striolate and bordered below, papillose above, trabeculate at back; endostome hyaline or yellowish, papillose, with a high basal membrane, broad and keeled segments (not or only narrowly perforate), and ciha ± well-developed. Calyptrae cucullate.

Discussion:The main generic characters are the differentiation of stem and branch leaves and well-differentiated, thick-walled alar cells.