10. Bryum caespiticiumHedw. 丛生真藓 cong sheng zhen xian Sp. Musc. Frond. 180. 1801. Hypnum caespiticium (Hedw.) Web. & Mohr, Index Mus. Pl. Crypt. 3. 1803. Type: Europe. Bryum capitellatum C. Müll., Nuovo Giorn. Bot. Ital., n.s., 5: 164. 1898, hom. illeg. Type: China. Shaanxi (Schen-si), May 1896, Giraldi s.n. Bryum sinensi-caespiticium C. Müll., Nuovo Giorn. Bot. Ital., n.s., 5: 165. 1898. Type: China. Shaanxi (Schen-si), Oct. 1896, Giraldi s.n. Plants small, ca. 10 mm high, pale yellowish green, slightly glossy, densely caespitose. Stems erect, branched by innovations. Leaves appressed when dry, not at all twisted, oblong-ovate to elliptical, cucullate near apex; margins slightly recurved below mid-leaf, entire, borders differentiated; costae reddish at base, long-excurrent, ending in long awns; median leaf cells hexagonal, 35–55 µm × 10–14 µm, thin-walled, gradually becoming narrower close to margins; apical cells similar to the median ones; basal cells hexagonal. Dioicous. Setae dark brown, 15–25 mm long; capsules inclined when dry, pendulous when moist, shortly cylindrical to pyriform; neck thick, dark reddish brown; opercula conic, slenderly rostrate; endostome segments perforate; basal membrane ca. 1/2 the height of teeth; cilia long, nodose. Spores 10–15 µm in diameter.
Small to medium-sized, scarcely lustrous plants, usually in dense tufts. Stems short, subflorally branched. Leaves imbricate and appressed when dry, erect-spreading when moist, ovate-oblong to ovate-lanceolate, acuminate, scarcely decurrent, distinctly bordered by much longer, narrower, and thicker-walled cells in 2-3 rows; margins entire, distinctly revolute; costa strong, usually long-excurrent; cells narrowly rhomboidal or narrowly oblong-hexagonal, longer above and rectangular below. Dioicous. Setae slender, usually 1.5-3 cm long; capsules nutant, oblong-pyriform, with a short, slender neck; operculum relatively large, nearly hemispheric, apiculate; endostome segments widely perforate, the cilia well developed, long-appendiculate. Spores 13-15 µm, roughened.
The plants are recognized by their caespitose habit and the oblong-acuminate leaves with reddish bases, recurved to revolute margins and long excurrent costae. See note under Ptychostomum turbinatum.
Plants small to medium-sized, caespitose, yellowish green or reddish green above, brownish below; terricolous. Stems 5-15 mm tall, frequently branching by subperichaetial innovations, densely tomentose below, red to reddish brown; rhizoids red-brown, coarsely papillose, tubers absent. Leaves frequently in successive comal tufts, smaller below, frequently concave, imbricate to erect, slightly twisted when dry, erect to erect-spreading when wet; oblong-lanceolate to ovate-lanceolate or ovate-oblong (1.1-)1.5-2.3(-2.7) mm long; apex acuminate; margins generally recurved to re volute, entire to denticulate at apex; border indistinct. Costa long-excurrent, awn 0.2-0.8 mm long, entire to denticulate above, reddish below; in section subround to round, laminal insertion ventral, ventral stereid band absent, ventral surface cells present, dorsal stereid band strong, stereids in 3-5 rows, dorsal surface cells incrassate, hydroids present between guide cells and stereid band. Upper laminal cells rhomboidal, infrequently pitted, (35-)40-67(-73) µm long, (10-)12-15(-19) µm wide, narrower towards margin; basal cells rectangular, frequently reddish below, pitted. Dioicous. Perichaetia terminal, leaves lanceolate to triangular. Seta 13-30 mm long, yellowish to reddish to reddish brown; capsule pendulous, oblong-cylindrical to clavate, yellowish to yellowish brown or reddish brown, frequently contracted below mouth when dry, urn 1-2 mm long, neck wrinkled when dry, 0.5-1.2 mm long; exothecial cells irregular rectangular, incrassate, smaller towards mouth, 1-3 rows at mouth transversely elongated; stomata on neck, phaneropore; peristome double, exostome teeth narrowly oblong-acuminate, yellowish, hyaline above, finely papillose, endostome segments tapering above, perforated, cilia 2-3, appendiculate, basal membrane high, yellowish or hyaline, smooth or minutely papillose; operculum conic, apiculate; calyptra cucullate; spores yellowish brown, 15-28 µm, minutely papillose.
Gemmabryum caespiticium is almost cosmopolitan in distribution. In southern Africa this species is infrequently collected at high elevations in and around Lesotho.
On moist soil or rocks in semi-shaded to open places; Baja California and Hidalgo.—Mexico; nearly cosmopolitan but absent in tropical and subtropical lowlands.
