Stems: with exterior cells in 2 or 3 rows, small, walls thick, interior cells larger, walls moderately thick. Leaves: with base undifferentiated or occasionally indistinctly decurrent; margins double-serrate from near base; costa stereid cells well developed on both sides of guide cells; juxtacostal basal cells often weakly differentiated, short- to long-rectangular, enlarged, lax or not; medial and distal laminal cells uniform, isodiametric, rounded to 4â6-sided, smooth, walls thick; marginal cells 2-stratose. Seta: wiry. Capsule: striate and flared at mouth when deoperculate; exothecial cells hexagonal [quadrate- to rectangular-rounded], walls moderately thick, somewhat weakly collenchymatous at base; stomata few at base and in neck, superficial. Distribution: se United States, Mexico, West Indies, Central America, South America, Asia, Africa, Pacific Islands, Australia, pantropical and southern temperate regions.
Discussion: Species 10 (1 in the flora).
Pyrrhobryum is characterized by elongate stems, distal and spirally arranged, broadly to narrowly lanceolate or linear-lanceolate leaves with double-toothed, 2-stratose margins, costae distally toothed abaxially, laminal cells mostly isodiametric and similar to near bases, and sporophytes positioned somewhat midway on stems or at bases.