Plants: small, green to yellowish. Stems: freely and irregularly branched; hyalodermis absent, central strand present; paraphyllia absent; rhizoids or rhizoid initials on stem or abaxial costa insertion, rarely forming tomentum, slightly to strongly branched, smooth; axillary hair distal cells 1 (or 2), hyaline. Stem: and branch leaves erect to spreading, straight or rarely subsecund, ovate to oblong-lanceolate, not plicate, 0.5–1 mm; base not decurrent; margins plane, entire or denticulate, limbidia absent; apex acuminate, acumen not furrowed; costa single, usually reaching mid leaf, sometimes shorter or to 3/4 leaf length; alar cells often well differentiated, subquadrate to transversely elongate, region broadly ovate or transversely triangular along margin; medial laminal cells short-oblong; marginal cells 1-stratose. Sexual: condition autoicous. Capsule: inclined to horizontal, cylindric, arcuate; peristome perfect; exostome teeth well developed, external surface cross striolate basally, margins dentate or slightly so; endostome basal membrane present, cilia usually well developed. Spores: 9–18 µm. Nearly worldwide.
Species 1. Amblystegium differs from Hygroamblystegium in its smaller size and weaker costa, this less than 30 µm wide at base, most often ceasing mid leaf; the costa rarely reaches 3/4 of leaf length but in such cases is straight, not curved as in Hygroamblystegium. Unlike the latter genus, Amblystegium lacks paraphyllia. Amblystegium is a terrestrial genus that sometimes occurs in swampy but never aquatic or subaquatic habitats.