Monographs Details: Diphyscium
Authority: Sharp, Aaron J., et al. 1994. The Moss Flora of Mexico. Part Two: Orthotrichales to Polytrichales. Mem. New York Bot. Gard. 69 (2)
Description:Genus Description - Small plants in dense mats. Stems lacking a central strand, with cortical cells poorly or not at all differentiated and cells short, rectangular, and thin-walled. Branches endogenous, emerging from the vicinity of rhizoid initials, with very fragile connections and usually easily detached from the stem when surrounding rhizoids are removed. Leaves very small below, progressively larger upward, strongly crisped and contorted when dry, lingulate, spatulate, or narrowly ovate-lanceolate, rounded-obtuse or broadly acute; margins plane, entire or irregularly crenulate, denticulate, or dentate above; costa strong, ending somewhat below the apex to very shortly excurrent; upper cells bistratose, isodiametric to transversely elongate, rather thick-walled, smooth to mammillose, sometimes pluripapillose; basal cells smooth, long-rectangular, hyaline, thin-walled. Typically dioicous with female plants notably larger. Perigonial leaves usually not much differentiated. Perichaetial leaves usually much longer than vegetative leaves, often sagittate, sometimes fimbriate above, with a long-excurrent costa. Vaginula very poorly developed. Capsules immersed on a very short, usually smooth seta, somewhat inclined, asymmetrically ovoid-conic, distinctly tapered toward the mouth, usually flattened on the upper surface; annulus present; operculum conic; peristome consisting of 16 very short exostome teeth in a single series and a large, conspicuous, 16-plicate, conic endostome. Calyptrae very small.
Discussion:Fertile plants are unmistakable owing to large, asymmetric capsules immersed among greatly differentiated and considerably enlarged perichaetial leaves with excurrent costae. Sterile plants (sometimes confused with members ofthe Pottiaceae) are easily recognized by bistratose leaf cells. In leaf sections it can be seen that the cells are superimposed in such a way that those of one layer alternate with those of the other. The position of rhizoid initials, in circular areas at the abaxial bases of costae, is highly distinctive.