From the Greek poly (many), trichos (a hair) and the Greek adelphos (a brother), in reference to the close relationship to the genus Polytrichum.

Dioicous. Plants loosely caespitose, dark green to brown. Stems erect, simple (rarely branched). Rhizoids restricted to subterranean part of stem. Leaves appressed when dry, recurved when moist; lamina linear-lanceolate, gradually narrowing to an acute apex, with ovate to subquadrate dorsal cells; margin serrate with unicellular teeth, distinctly upcurved, unistratose; costa slightly excurrent, reddish brown, apically sharply serrate with abaxial teeth; sheathing base ovate, gradually or abruptly narrowing to lamina, with subquadrate to rectangular cells with firm walls; lamellae almost covering the lamina.

Calyptra sparsely hairy. Setae usually solitary, terminal or pseudolateral by subperichaetial innovation. Capsules inclined, pale to dark brown; urn with 2 distinct angles (crescent-shaped in cross-section); exothecial cells subquadrate, with firm walls; stomata restricted to basal third of capsule; operculum rostellate. Peristome teeth 64, pale brown; epiphragm thin, attached to peristome teeth apices. Spores with a granulose surface.

Native.

A genus of about ten species in Australia, New Zealand, New Guinea, South America and Tristan da Cunha. Represented in Australia by the non-endemic P. magellanicus.

Polytrichadelphus magellanicus is a pioneer of soil in open habitats.

Polytrichadelphus (Müll.Hal.) Mitt., J. Proc. Linn. Soc., Bot. 4: 97 (1860). Type: Polytrichadelphus magellanicus (Hedw.) Mitt.

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

First published as: J. Hyvönen (2006), Polytrichaceae: Polytrichadelphus, Fl. Australia 51: 136–137. Australian Biological Resources Study, Canberra & CSIRO Publishing, Melbourne.