Meesia longiseta Hedw., Sp. Musc. Frond. 173. 1801.
Protologue. In turfosis paludosis Sueciae, Berolini, Erlangae, in monte pinifero Franconiae.
Plants small to medium-sized in yellow‑green tufts. Stems to 1 cm high, tomentose below. Leaves somewhat 3-ranked, spreading or wide‑spreading from an erect base, not much altered when dry, 2–3 mm long, ovate‑lanceolate, moderately keeled above, decurrent; apices acute or rounded‑obtuse; margins entire or obscurely and bluntly serrulate, plane or weakly revolute at base; costae subpercurrent; upper leaf cells short-rectangular to narrowly long‑rectangular, 24–50 μm long, thin to firm‑walled, smooth, basal cells laxly rectangular, enlarged, bulging, thin‑walled, to 60 μm long. Synoicous. Perichaetial leaves 4–7 mm long. Setae 6–10 cm long. Capsules 2.0–3.5 mm long, pyriform, curved and asymmetric from an erect neck; opercula bluntly conic, 0.5 mm long; exostome teeth short, blunt or truncate, outer (dorsal) surface lightly thickened and faintly horizontally striate, inner (ventral) surface more strongly thickened than the outer surface, inner trabeculae thickened and projecting, endostome 2–4 times as long as the exostome teeth, basal membrane low, segments narrow, keeled, slightly perforate, outer (dorsal) surface smooth, often with yellow, irregular, often discontinuously thickenings, inner (ventral) surface hyaline, lightly thickened, cilia 2–4, rudimentary. Spores 36–44 μm, brown, lightly papillose.