Plants: small. Stems: irregularly branched. Stem: and branch leaves similar, triangular or ovate; margins weakly toothed to entire; ecostate or costa single; medial laminal cells more than 5:1. Seta: red-brown, 0.8–2 cm. Capsule: suberect, inclined, or rarely erect, symmetric; operculum conic; peristome perfect. North America, Europe, Asia, Atlantic Islands, Pacific Islands.
Species 11 (5 in the flora). Isothecium occurs mainly in temperate to subtropical regions and grows in dense, pendent wefts with creeping stems. The primary stem leaves are squarrose and distant, and erect-spreading, strongly imbricate, or occasionally wide spreading. The setae are smooth; the peristome is yellow.