Grimmia trichophylla Grev., Fl. Edin. 235. 1824.
Protologue: Scotland. Edinburgh, s. coll.; Arthur's Seat and coast of Fife, Arnott; Lanark Road, Edinburgh, s. coll.; walls between Colinton and the Pentland Hills, s. coll. Lectotype (Geissler & Maier 1995). [Great Britain] near Edinburgh. 1821 (E).
Plants small to large in dense or loose cushions or tufts, brown below, yellowish green to olive‑green, often hoary due to long hair‑points. Stems erect, fastigiate branched, 5–30 mm high, central strand present; rhizoids sparse. Leaves erect to erect‑patent, somewhat twisted when dry, erect‑spreading when wet, 2–2.5 mm long, linear‑lanceolate from a narrowly ovate‑lanceolate base, keeled, long-acuminate, hair‑point long, short or absent, entire or weakly denticulate; margins bistratose, occasionally unistratose, recurved on one or both sides, entire; costa percurrent, terete at back; laminae unistratose except at extremely apex or bistratose in scattered patches; cells smooth, upper cells 6–8 x 6 μm, irregularly quadrate to short‑rectangular or transversely rectangular, incrassate, with straight or sinuose walls, basal cells near costa 20–40 x 6–8 μm, elongate‑rectangular, strongly sinuose, basal marginal cells 8–20 x 12 μm, quadrate to rectangular, with thick transverse walls and thin longitudinal walls. Gemmae usually present, sessile on the dorsal side of the upper lamina. Dioicous. Setae cygneous or flexuose, 2–5 mm long, twisted when dry, yellow. Capsules exserted, 1.5–2 mm long, oblong, horizontal to pendent, furrowed; stomata superficial in neck; opercula erect‑ or oblique‑rostrate, 0.5–1 mm long; peristome teeth 16, narrowly triangular, red, densely papillose, entire or irregularly cleft into 2–3 parts, 200–300 μm long. Spores 10–15 μm, papillose. Calyptrae yellow, mitrate, 1.5 mm long.