“horn-leaved earth moss”
How to recognize Tortula acaulon: Horn-leaved earth moss, formerly known as Phascum acaulon or Phascum cuspidatum, is a small, yellow-green cushion moss that grows on the ground on disturbed bare soil. The 2-3.5 mm long leaves are ovate-acuminate, with the costa or midrib extending well past the apex of the blade of the leaf, forming a long yellow-red awn. The cells have C-shaped papillae. The sporophytes grow with a 0.3 mm long stem, and, being tightly clasped by the surrounding leaves, are hidden from view. The 1-1.5 mm capsules are ellipsoid to globose with a blunt apiculus and are cleistocarpous which means they open along an irregular tear to release the spores.
Where to find Tortula acaulon: Horn-leaved earth moss grows scattered or clustered on bare patches of clayey, usually calcareous soil in fallow fields and roadsides. Sporophytes mature in winter or early spring. The species is known from several widely scattered locations in Ohio, and, like several other mosses of arable land, is probably more common than the few records indicate.