Monographs Details: Chryso-hypnum
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:Hypnaceae
Scientific Name:Chryso-hypnum
Description:Genus Description - Plants small, in yellow- to dark-green or brownish-yellow, ± shiny mats. Stems creeping, in section elliptic, with a weakly developed central strand, regularly to irregularly pinnate-branched; branches horizontal or ascending, subcomplanate-foliate to julaceous, ± curved; pseudoparaphyllia subfilamentous to narrowly lanceolate. Stem and branch leaves slightly differentiated: Stem leaves loosely imbricate to squarrose, weakly concave, ovate to triangular-ovate, ± cordate and slightly decurrent at base, ± abmptly acuminate, slightly plicate; margins recurved below, sermlate above, sometimes nearly to the base; costa double, up to 1/3 the leaf length, rarely obscure; upper median cells linear or oblong-linear, projecting as papillae at both upper and lower angles; alar cells weakly to rather distinctly differentiated, quadrate to short-rectangular. Branch leaves smaller and narrower, more prominently sermlate. Autoicous. Perichaetial leaves oblong- to triangular-lanceolate, gradually long-acuminate, ± striate; costa double to obscure. Setae yellow- to red-brown, smooth; capsules inclined to pendulous, ovoid or oblong-cylindric, ± curved, constricted below the mouth when dry and empty; annulus present; operculum conic-obtuse or conic-rostellate; exothecial cells rounded-hexagonal to rectangular; exostome teeth lance-subulate, pale-yellow, densely cross-striolate below, pale and finely papillose above, with low trabeculae; endostome nearly as long as the exostome teeth, finely papillose, consisting of a high basal membrane and keeled segments split along the median hne and alternating with 1-3 weakly nodulose cilia. Spores minutely papillose. Calyptrae ± sparsely hairy.

Discussion:Chryso-hypnum is separated from Mittenothamnium by non-stipitate, creeping stems, leaf cells projecting at both upper and lower angles, and subfilamentous to narrowly lanceolate pseudoparaphyllia. Fleischer's treatment (1908) of Stereohypnum (including both Mittenothamnium and Chryso-hypnum) described before 1861 is a valuable source of information. Chrysohypnum also resembles Ctenidium but differs in stem leaves with shorter acumina, shorter decurrencies, and subentire or slightly sermlate basal margins, as well as subfilamentous to narrowly lanceolate pseudoparaphyllia.