Phascum acaulon Withering, Syst. Arr. Brit. Pl. ed. 4., 3: 768. 1801 (as acaule); Microbryum floerkeanum var. henrici Renauld & Cardot; Phascum cuspidatum Hedwig; P. cuspidatum var. americanum Renauld & Cardot; P. cuspidatum var. henrici (Renauld & Cardot) Wijk & Margadant; P. cuspidatum var. piliferum (Hedwig) Hooker & Taylor; P. cuspidatum var. schreberianum (Dickson) Bridel; Tortula acaulon var. pilifera (Hedwig) R. H. Zander; T. acaulon var. schreberiana (Dickson) R. H. Zander; T. atherodes R. H. Zander; T. atherodes var. pilifera (Hedwig) R. H. Zander; T. atherodes var. schreberiana (Dickson) R. H. Zander

Leaves ovate to oblong-lanceolate, apex acute, mucronate to short-awned, occasionally comparatively long-awned, margins recurved proximally to nearly plane, not or weakly bordered distally with slightly thicker-walled cells; costa excurrent, lacking an adaxial pad of cells, distally narrow, 2(-3) cells across adaxial surface; distal laminal cells distally quadrate-hexagonal, width 13-17 µm, 1:1, weakly simply papillose or smooth. Sexual condition autoicous. Sporophytes immersed. Seta very short. Capsule cleistocarpic, spheric to very short-ellipsoid, erect, mostly 0.9-1.3 mm; peristome absent; operculum not differentiated. Spores (25-)33-40 µm, spheric, densely papillose.

Capsules mature winter-spring. Soil, lawns, fields, banks; low to moderate elevations; Alta., B.C., N.S., Ont., Que., Sask.; Alaska, Ariz., Ark., Calif., Colo., Conn., Del., Fla., Idaho, Ill., Ind., Iowa, Kans., La., Md., Mich., Minn., Mo., Mont., Nebr., Nev., N.J., N.Mex., N.Y., N.C., Ohio, Okla., Oreg., Pa., S.Dak., Tenn., Tex., Utah., Va., Wash., W.Va., Wis.; Mexico; Europe; Asia; n Africa; Pacific Islands (New Zealand).

The varieties pilifera and schreberiana are not recognized here. The former name may be used for plants with long awns, and the latter for robust specimens ranging to 1 cm tall, but intergrades appear to be common.