Fieldiana, Bot., n. s. 1: 6, figs. 1, 2. 1979.
Plants medium-sized to large, in dense to loose mats, green, dark green, yellowish, or brownish. Stems creeping, densely to moderately densely terete-foliate to homomallous, irregularly loosely branched, branches densely terete-foliate to homomallous; central strand present; pseudoparaphyllia with apex obtuse to acute; axillary hairs of 2–4 cells, cells short, 1.5–2.5:1. Stem leaves erect-appressed to erect-spreading, closely foliate, often imbricate, broadly ovate to ovate-oblong, concave, shallowly longitudinally plicate; base scarcely decurrent; margins serrulate to serrate throughout; apex broadly acute, sometimes abruptly cuspidate or short-apiculate; costa short-excurrent, percurrent, or to 80–95% leaf length, stout, terminal spine absent or occasionally present; alar cells somewhat enlarged or almost undifferentiated from adjacent cells; laminal cells elongate to linear, walls moderately thick; basal cells ovate-rectangular, short. Branch leaves slightly differentiated, usually narrower. Sexual condition dioicous; perichaetial leaf acumen slightly reflexed. [Seta reddish, rough. Capsule inclined to horizontal, reddish brown, plump, slightly curved; operculum rostrate; peristome xerocastique, perfect. Calyptra naked. Spores 12–16 µm].
e North America, Mexico, e Asia, Pacific Islands (Hawaii).
Species 4 (2 in the flora).
There are contrasting opinions on the systematic position of Donrichardsia. The genus was described in Amblystegiaceae and subsequently segregated in its own family, Donrichardsiaceae (R. Ochyra 1985). According to S. Huttunen et al. (2006) and Huttunen and M. S. Ignatov (2010), Donrichardsia includes aquatic species closely related to and possibly derived from Oxyrrhynchium, while J. T. Wynns et al. (2009) suggested merging this genus with Oxyrrhynchium. The plants are rigid and not or slightly glossy with stems occasionally curved at their ends; the branches are creeping to ascending; and the axillary hairs are pigmented throughout. Sporophytes have not been found in North America.