6. MacrothamniumFleisch. 南木藓属 nan mu xian shu
Hedwigia 44: 307. 1905.
Plants medium-sized to large, dull or slightly glossy, yellowish green or yellowish brown, in loose or dense mats. Main stems elongate and prostrate; secondary stems usually curved, sometimes nearly dendroid, irregularly or regularly 1–3-pinnately branched, central strand poorly developed, consisting of small and thin-walled cells, an inner parenchyma of larger cells with thin walls, and a sterome of small, thick-walled cells, the epidermis usually not differentiated from the sterome, but occasionally with larger, thin-walled and hyaline cells; paraphyllia absent; pseudoparaphyllia triangular or lanceolate; rhizoids on tips of branches and main stems, few. Stem leaves and branch leaves differentiated; stem leaves erect to spreading, cordate, reniform or broadly ovate, obtuse, acute or acuminate at apex, usually cordate at base, decurrent or not decurrent, somewhat concave, occasionally somewhat plicate; margins reflexed at base, serrate above, serrulate below; costae double, 1/4–1/2 the leaf length, sometimes indistinct; median leaf cells narrowly oblong to linear, approximately 5–12:1, smooth or rarely finely papillose, pitted or slightly pitted at base; alar cells not differentiated, or sometimes conspicuously inflated; branch leaves more closely arranged, spreading, rounded ovate or oblong, acute or short-acuminate at apex, not or slightly decurrent; costae weak; laminal cells prorate; alar cells not differentiated. Dioicous. Perichaetia on main stems. Setae elongate, smooth, reddish; capsules erect or slightly inclined, symmetric, usually with a short apophysis, constricted below the mouth or irregularly plicate when dry; exothecial cells isodiametric or rectangular, stomata superficial at base of capsules; annuli consisting of 2–3 rows of small cells, sometimes absent; opercula conic; peristome double; exostome teeth yellow, orange yellow, reddish brown at base, lanceolate, slightly bordered; outer surface irregularly or regularly cross-striate and papillose, rarely perforated along median line; endostome segments yellow, smooth or papillose, narrowly perforated; basal membrane 1/4–1/2 the length of segments; cilia 2–4, nodulose or absent. Calyptrae cucullate, smooth, naked. Spores spherical, finely papillose, 8–33 µm in diameter.