4. Grimmia donniana Sm. 卷边紫萼藓 juan-bian zi-e xian
Engl. Bot. 18: 1259. 1804. Dryptodon donnianus (Sm.) Hartm., Handb. Skand. Fl. (ed. 3), 270. 1838. Grimmia obtuse var. donniana (Sm.) Hartm., Handb. Skand. Fl. (ed. 5), 377. 1849. Type. United Kingdom: North Wales, July 1802, D. Turner s.n. (lectotype BM, designated by Muñoz 1998b).
small, up to 1.0 cm high, dark green to blackish, in small, dense cushions. Stems
sparsely branched, with well developed central strand in cross section. Leaves
imbricate, slightly curved when dry, spreading when moist, 1.7–2.4 mm long, elongate-lanceolate to narrowly lanceolate from an ovate base, strongly keeled, ending with narrow, nearly smooth, 0.2–0.6 mm long, hyaline hair-points; the lower leaves small, muticous; margins plane throughout, bistratose above; costa single, percurrent, with small median cells in cross section; upper cells bistratose, rounded-quadrate, 7–9 µm wide, with slightly sinuose walls; median cells rectangular, 9–16 µm × 7–8 µm, sinuose; basal marginal cells rectangular, 35–70 µm × 9–11 µm, hyaline, rather thin-walled; basal juxtacostal cells elongate-rectangular, 35–70 µm × 7–8 µm, more or less transparent, with somewhat thickened, straight walls. Autoicous
. Perichaetial leaves
similar to the upper stem leaves; perigonia often on branches arising from older basal parts of stems. Setae
yellowish brown, 1.6–1.8 mm long, twisted to left when dry, straight when moist; capsules emergent, erect, ovate to elliptic, smooth, yellowish brown, 1.0–1.2 mm long; exothecial cells rectangular to rounded-quadrate, thin-walled; stomata near base of urn; annuli consisting of quadrate to short-rectangular, thick-walled cells in 2–3 rows; opercula convex, with short, straight, blunt beaks; peristome teeth erect, lanceolate, yellowish brown, ca. 0.18–0.20 mm long, hardly split and perforate above, outer surface densely papillose in upper half, papillose in lower half, inner surface papillose throughout. Calyptrae
small, mitrate. Spores
9–10 µm in diameter, finely granulose.