From the Greek poly (many), trichos (a hair) and the Latin -astrum (indicating likeness or inferiority), in reference to the relationship to Polytrichum.

Dioicous. Plants loosely caespitose, bright green to brown. Stems erect, simple or branched. Rhizoids restricted to stem base and bases of lowermost scale-like leaves. Leaves appressed, erect-spreading when dry, erect-spreading to distinctly recurved when moist; lamina linear-lanceolate, gradually narrowing to a sharp apex, with ovate to subquadrate abaxial cells; margin serrate with large teeth, distinctly upcurved to flat, unistratose; sheathing base ovate, abruptly or gradually narrowing to lamina, with subquadrate to rectangular cells with firm walls; costa slightly excurrent, reddish brown, apically sharply serrate with abaxial teeth; lamellae almost covering the lamina.

Calyptra hairy. Setae usually solitary, terminal or pseudolateral by subperichaetial innovation, smooth. Capsules erect or slightly inclined, pale to dark brown; urn cylindrical, terete to faintly plicate; exothecial cells smooth, subquadrate to elongate, with firm walls; stomata restricted to basal hypophysis; operculum rostellate. Peristome teeth c. 64, pale brown; epiphragm thick. Spores with a granulose surface.

A genus of approximately 15 species in both hemispheres. Represented in Australia by two non-endemic species.

Polytrichastrum is a pioneer plant of open soil and peat.

Polytrichastrum G.L.Sm., Mem. New York Bot. Gard. 21(3): 35 (1971). Type: Polytrichastrum alpinum (Hedw.) G.L.Sm.

J. Hyvönen (2012), Australian Mosses Online 48. Polytrichaceae. Australian Biological Resources Study, Canberra. Version 20 June 2012. 

First published as: J. Hyvönen (2006), Polytrichaceae: Polytrichastrum, Fl. Australia 51: 137–140. Australian Biological Resources Study, Canberra & CSIRO Publishing, Melbourne.