75. Leucodontaceae Schimper
Richard H. Zander
Plants medium-sized to large, in loose mats. Stems creeping, sympodial, stoloniferous; secondary stems ascending, irregularly branched, branches few to many, curved or in whorls; paraphyllia absent; radiculose on primary stems. Leaves crowded, imbricate when dry, spreading when moist, ovate, ovate-lanceolate, or cordate-ovate; margins entire, serrate, or serrulate; apex acuminate or acute; ecostate or costa double or more [single], short; alar cells differentiated, many; laminal cells ovate to elliptic, smooth, rarely singly papillose, or occasionally prorate, walls thick; basal cells longer. Sexual condition dioicous; perigonia axillary or borne on secondary stems or branches, deltoid-apiculate or gemmiform; perichaetia borne on main stem or lateral branches. Seta short to elongate. Capsule erect, immersed to exserted, smooth; annulus present or sometimes absent; operculum conic or oblique-rostrate; peristome double; exostome teeth 16, pale; endostome basal membrane low or absent, segments absent, weakly developed, or rarely well developed, cilia absent. Calyptra cucullate, naked or hairy. Spores anisosporous, occasionally large, papillose.
Genera 7, species ca. 40 (3 genera, 6 species in the flora): nearly worldwide, except Australia, Oceania, and Antarctica; temperate and tropical regions.
Leucodontaceae have been circumscribed variously in recent years, with the broad concept of M. G. Manuel (1974) modified by recent phylogenetic reappraisals (W. R. Buck and B. Goffinet 2000) of the taxonomic position of Alsia and Forsstroemia (in Leptodontaceae), Bestia (in Lembophyllaceae), Dendroalsia (in Cryphaeaceae), and Pseudocryphaea (in Rutenbergiaceae). The main traits of Leucodontaceae are the epiphytic habit, sympodial stems with curved, ascending secondary branches, ovate to ovate-lanceolate leaves, costa usually absent or short and double, laminal cells ovate or elliptic, thick-walled, seldom papillose, and endostome commonly reduced.
SELECTED REFERENCE Manuel, M. G. 1974. A revised classification of the Leucodontaceae and a revision of the subfamily Alsioideae. Bryologist 77: 531-550.