Hymenodon
Dioicous or rhizautoicous. Asexual reproduction by filamentous, reddish-brown gemmae in leaf axils (not in Victoria). Mats or tufts on tree fern trunks, rarely on rock. Stems simple or branching in lower quarter (not in Victoria), with rhizoids confined to base; central strand present. Leaves elliptic, ovate or lanceolate, spirally arranged, sometimes appearing distichous, unranked, monomorphic, little altered when dry; apex acute or obtuse, with long, white hairpoint; hairpoint sometimes caducous (not in Victoria); costa subpercurrent to percurrent (not in Victoria); margins crenulate to dentate (not in Victoria), plane, without a border; laminal cells circular or quadrate to short-rectangular, similar throughout, mammillose; alar cells not differentiated. Pleurocarpous; perichaetia and perigonia near base. Capsules vertical to inclined, straight, cylindric, ellipsoid, ovoid or subglobose (not in Victoria), without an annulus or annulus weakly differentiated. Calyptra cucullate, smooth, glabrous. Operculum rostrate. Peristome single; exostome absent (not in Victoria) or of 16 segments, with a low basal membrane; endostome and cilia absent.
Eight species in Malesia, the south-west Pacific, Central and South America and the Caribbean Islands (Tessler 2012); 1 species in Victoria.
The single peristome usually present in Hymenodon was traditionally thought to be an endostome, but scanning electron microscopy of the peristome revealed a cell arrangement consistent with this peristome being equivalent to an exostome (Shaw & Anderson 1986).
SpinningShaw, J.; Anderson, L.E. (1986). Morphology and homology of the peristome teeth in Hymenodon and Hymenodontopsis (Rhizogoniaceae: Musci). Systematic Botany 11: 446–454.
Tessler, M. (2012). A monograph of Hymenodon (Orthodontiaceae). The Bryologist 115: 493–517.
