Thuidium

• Authority

  Sharp, Aaron J., et al. 1994. The Moss Flora of Mexico. Part Two: Orthotrichales to Polytrichales. Mem. New York Bot. Gard. 69 (2)

• Family

  Thuidiaceae

• Scientific Name

  Thuidium

• Description

  Genus Description - Fairly robust plants in dull, green, yellowish, or brownish, loose mats. Stems creeping to ascending, often 1-3-pinnate and often frondose; paraphyllia abundant, papillose, branched-polymorphous. Stem and branch leaves differentiated. Stem leaves ovate or subcordate, acuminate, narrowed to the base and somewhat decurrent, generally ± biphcate; margins ± revolute below, not or somewhat toothed above; costa ending below the apex or, rarely, excurrent; cells mostly uniform, rounded- to oblong-hexagonal, firm- or thick-walled, unipapillose or, less often, pluripapillose at back. Leaves of primary branches often rather similar to stem leaves; leaves of secondary and tertiary branches much smaller than the other leaves, concave, with erect margins, mostly ovate, acute or sometimes obtuse or rounded, usually ending in a tmncate cell with more than 1 papilla, and costa shorter and weaker. Perichaetial leaves elongate, erect, pale, lanceolate or ovate-lanceolate, long-acuminate, sometimes ciliate at the margins; costa ending in the acumen or subpercurrent; cells elongate, smooth or somewhat papillose. Setae elongate, smooth; capsules inclined to horizontal and ± curved, oblong-cylindric, smooth; annulus of 2-3(-4) irregular rows of cells; operculum conic or convex-conic, often obliquely rostrate; exostome teeth yellow or yellow-brown; cilia of endostome ± nodulose, in groups of 2 to 4 (rarely rudimentary or lacking). Calyptrae naked.

• Discussion

  Regularly pinnate branching, abundant paraphyllia, papillose leaf cells, and obvious differentiation of stem and branch leaves are important features of the genus. It differs from Cyrto-hypnum in its larger size, dioicous inflorescences, leaf cells papillose only at back, and smooth setae.