48. Racopilaceae Kindberg
William D. Reese
Plants medium-sized, in creeping mats, dark green. Stems short to elongate, subpinnate or irregularly branched, branches spreading, short, densely tomentose proximally; axillary hairs of 5 cells, basal cell short, brownish. Leaves usually dimorphic, in 4 rows, twisted-contorted when dry, spreading-erect when moist; lateral leaves in 2 rows, larger; dorsal leaves in 2 rows, usually much smaller; oblong-ovate [ovate-acuminate]; margins toothed distally, unbordered [bordered]; apex broadly acute [rounded]; costa single; medial laminal cells quadrate to rhomboidal, smooth [1-papillose]. Sexual condition autoicous or synoicous [dioicous or monoicous]; perigonia gemmiform, leaves small, apex long-awned; perichaetial leaves differentiated. Seta single or rarely 2 per perichaetium, elongate, smooth. Capsule exserted, curved [straight]; operculum beaked or rostrate; peristome double; exostome cross striolate proximally, slender and papillose distally; endostome basal membrane high, papillose, cilia present or absent. Calyptra cucullate or rarely mitrate, hairs usually few to many, long, delicate. Spores smooth [rough].
Genera 2, species ca. 70 (1 in the flora): nearly worldwide; primarily tropical and subtropical regions. The second genus in Racopilaceae is Powellia Mitten with six Asian species.
SELECTED REFERENCE Reese, W. D. 1999. Racopilum tomentosum: First report of its sporophytes in Florida, and observations on its sexuality. Evansia 16: 59-60.