Dale H. Vitt

Plants small to large, in tufts, cushions, or mats, dark green, reddish brown, or olive brown, dull. Stems erect-ascending and often 2-fid, or creeping, branches many, erect or ascending, simple or 2-fid; outer cell walls thick, central strand absent, inner cells uniform, walls thin. Leaves erect-appressed, crowded, spirally twisted, flexuose, crisped, or contorted when dry, erect-spreading to squarrose-recurved when moist, ovate-lanceolate, ligulate-oblong, or lanceolate-linear, ± channeled; base not decurrent (decurrent in Zygodon); margins usually plane to revolute, rarely involute to erect, entire or sometimes denticulate near apex; apex rounded-obtuse, acute, occasionally acuminate, apiculate, or awned; costa strong, ending near apex; alar cells rarely differentiated; basal laminal cells rectangular, elongate-linear, quadrate, rounded, or elliptic; distal cells rounded-hexagonal, rarely rectangular, usually small, papillae 1-4(-6) per cell, conic or 2-fid, rarely smooth or mammillose, walls often incrassate. Specialized asexual reproduction occasional, by gemmae. Sexual condition usually gonioautoicous or dioicous, rarely pseudautoicous or cladautoicous; perigonia terminal or lateral, sometimes occurring on dwarf male plants, budlike, large; perichaetia terminal, further branching occurring by innovations, perichaetial leaves sometimes larger than stem leaves. Seta erect, dextrorse or sinistrorse, smooth or rarely rough. Capsule erect, immersed, emergent, or exserted, ovate to cylindric-fusiform, symmetric, smooth or 8-ribbed, rarely 16-ribbed, sometimes constricted below mouth; exothecial cells rectangular to elliptic, often differentiated into bands; stomata superficial or immersed, usually below mid capsule, well developed; annulus poorly developed or absent; operculum convex to conic, rostrate; peristome double, single, rudimentary or rarely absent; prostome sometimes present, usually fragmentary; exostome teeth 16, usually connate in 8 pairs, erect, recurved, or reflexed, lanceolate, thick, densely papillose or striate; endostome segments 8 or 16 when present, hyaline, thin, linear-lanceolate, alternating with exostome teeth or connate to form rudimentary membrane, cilia absent. Calyptra mitrate or rarely cucullate, usually large and conspicuous, hairy or naked, plicate or not. Spores isosporous or anisosporous.

Genera 22, species ca. 380 (9 genera, 71 species in the flora): nearly worldwide.

SELECTED REFERENCE Vitt, D. H. 1971. The Family Orthotrichaceae (Musci) in North America, North of Mexico. Ph.D. dissertation. University of Michigan.

Lower Taxa

• Amphidium Schimper
• Drummondia Hooker
• Groutiella Steere
• Macrocoma (Hornschuch ex Müller Hal.) Grout
• Macromitrium Bridel
• Orthotrichum Hedwig
• Schlotheimia Bridel
• Ulota D. Mohr
• Zygodon Hooker & Taylor