1. Racopilum tomentosum (Hedwig) Bridel, Bryol. Univ. 2: 719. 1827.
Hypnum tomentosum Hedwig, Sp. Musc. Frond., 240. 1801
Lateral leaves slightly asymmetric, 1.5-2 × 0.8 mm; margins coarsely serrate distally; costa long-excurrent; medial laminal cells 13-16 µm. Dorsal leaves narrowly triangular-acuminate, 1 × 0.5 mm; costa long-excurrent; medial laminal cells 10-15 µm. Seta brown, 1.4-2.7 cm. Capsule brown, 3-4 mm; operculum obliquely rostrate, 2.5 mm. Calyptra tardily cucullate, 2.5-3 mm. Spores 13-15 µm.
Capsules mature late Jan. Limestone, base of trees, rotted wood, humus, low and humid forests; low elevations (0-50 m); Fla.; Mexico; West Indies; Central America; South America.
Racopilum tomentosum is unmistakable due to the creeping stems, which are heavily tomentose ventrally in older portions, and the dimorphic leaves twisted-contorted when dry and spreading-erect in four rows when moist. Some of the Florida specimens have gametoecia (for example, Philips 97), but only a single collection with sporophytes is known from the flora area (Collier Co., Anderson & Crum 13440, Mosses of North America 595, DUKE, FLAS, LAF). Some duplicates of this issue may lack sporophytes.