BFNA Title: Racopilaceae
Author: W. D. Reese
Date: April 26, 2008
Edit Level: R
Version: 2a

Bryophyte Flora of North America, Provisional Publication

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William D. Reese

Plants medium-sized, creeping, dark green. Stems short to elongate, subpinnate or irregularly branched, with short, spreading branches, densely tomentose in older parts; axillary hairs 5-celled, proximal cell short, brownish. Leaves mostly dimorphic, in 4 rows, twisted-contorted when dry, spreading-erect when wet; large leaves in 2 lateral rows, usually much smaller leaves in 2 dorsal rows; leaves oblong to ovate-acuminate, toothed distally, bordered or unbordered; apex rounded to acute; costa strong; medial cells quadrate to rhomboidal; smooth or 1-papillose. Sexual condition dioicous or monoicous. Perichaetial leaves differentiated. Seta single (rarely two per perichaetium), elongate, smooth. Capsule exserted, straight or curved; operculum beaked or rostrate; peristome double, cilia present or lacking. Calyptra cucullate, rarely mitrate, usually with few to many long, delicate hairs. Spores smooth or rough.


Genera 1(--2), species ca. 66 (1 genus, 1 species in the flora): primarily tropical and subtropical regions of the world.


SELECTED REFERENCE Reese, W. D. 1999. Racopilum tomentosum: First report of its sporophytes in Florida, and observations on its sexuality. Evansia 16: 59--60.


1. RACOPILUM Palisot de Beauvois, Prodr., 36. 1805 * [Greek rachos, rags, and pilo, cap, alluding to the basally torn calyptra of some taxa]


Plants in low tangled mats. Branches sometimes with leafless flagelliform tips. Leaves dimorphic, ovate-acuminate, unbordered; apex acuminate; costa excurrent; medial cells smooth. Sexual condition autoicous, mostly pseudautoicous with dwarf male plants. Perichaetial leaves small, long-awned. Perigonia gemmiform, axillary, with small, long-awned leaves. Capsule curved, sulcate when dry; operculum rostrate; peristome teeth with zigzag median line, cross-striolate proximally, slender and papillose distally; endostome with tall basal membrane, segments delicate, papillose, cilia delicate, nodose, stomates present proximally. Calyptra usually with delicate hairs proximally, sometimes naked with age. Spores smooth.


Species ca. 63 (1 species in the flora): worldwide in tropical and subtropical regions.


1. Racopilum tomentosum (Hedwig) Bridel, Bryol. Univ. 2: 719. 1827


Hypnum tomentosum Hedwig, Sp. Musc., 240. 1801


Lateral leaves slightly asymmetric, oblong-ovate, 1.5--2 x 0.8 mm, coarsely serrate distally, apex broadly acute; costa long-excurrent, medial cells 13--16 \um. Dorsal leaves narrowly triangular-acuminate, 1 x 0.5 mm, costa long-excurrent; medial cells 10--15 \um. Sexual condition autoicous or synoicous. Seta brown, 14--27 mm. Capsule brown, 3--4 mm; operculum obliquely rostrate, 2.5 mm. Calyptra tardily cucullate, 2.5--3 mm. Spores 13--15 \um.


Capsules mature late January. Limestone, tree bases, rotted wood, humus, low humid forests; 0-- 50 m; Fla.; Mexico; West Indies; Central America; South America.


The creeping stems, which are heavily tomentose ventrally in older portions, and the dimorphic leaves twisted-contorted when dry and spreading-erect in 4 rows when wet, make Racopilum tomentosum unmistakable. Some of the Florida specimens have gametoecia (e.g., 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.