Hypnaceae

Diagnosis: Plants slender to medium-sized in mostly pale-green, thin mats. Stems long-creeping, to 10 cm long, the branches complanate-foliate, < 1 cm long. Stem and branch leaves somewhat differentiated, ventral, dorsal and lateral stem leaves strongly differentiated, the ventral ones symmetric, oblong-ovate, 0.65-0.95 mm long, gradually long-acuminate, the dorsal ones somewhat asymmetric, ovate, 1-1.3 mm long, gradually acuminate, concave, the lateral ones strongly asymmetric, often cultriform, ovate-oblong, 0.85-1.2 m long, ± abruptly acuminate, concave; all stem leaves with margins distantly subserrulate throughout, plane; cells long-hexagonal to linear, 8-20:1, smooth but with thickened end walls given the impression of prorulae, somewhat porose toward the insertion; alar cells mostly yellow, 2-4 cells enlarged in extreme basal angles, oblong, sometimes absent on one side of the lateral leaves. Branch leaves with dorsal and lateral leaves differentiated, the dorsal ones 1/2 as many as the later ones, symmetric, erect-spreading, lanceolate, 0.8-1.1 mm long, gradually acuminate, the lateral ones somewhat asymmetric, wide-spreading, sometimes subfalcate, oblong-ovate, 1.1-1.3 mm long, gradually or ± abruptly acuminate, somewhat concave; all branch leaves with margins subentire to serrulate throughout, the lateral leaves more strongly toothed, plane to narrowly recurved above; cells linear to linear-flexuose, 10-20:1, smooth, sometimes becoming shorter in the acumen, somewhat porose toward the insertion; alar cells yellow, 3-5 cells enlarged in extreme basal angles, oblong. Sporophytes not seen.

Distribution: Central America; Caibbean; Western and Northern South America, Brazil; Central Africa, Madagascar

Ecology: On tree trunks, especially at the bases, occasionally on logs, mostly in moist forest.

Notes: The heterophyllous leaves with yellowed insertions are distinctive.

Basionym: Hypnum trinitense Müll. Hal.

Basionym Citation: Synopsis Muscorum Frondosorum omnium hucusque Cognitorum 2: 284. 1851.

Other Published Figures: W. R. Buck. 1998. Pleurocarpous mosses of the West Indies. Plate 121 (1-10).