Plants: large, in thin to loose mats, light green or whitish, sometimes yellowish, dull or somewhat glossy. Stems: creeping or sometimes erect, sparingly and irregularly branched, occasionally simple; hyalodermis present, sometimes indistinct, central strand sometimes present; pseudoparaphyllia absent. Stem: and branch leaves similar, imbricate, somewhat contorted, strongly undulate, especially near apex, ovate to ovate-lanceolate, rarely oblong-lanceolate, not plicate; base weakly decurrent; margins plane, entire or usually serrulate to serrate at apex; apex acute to acuminate, rarely somewhat obtuse; costa double, ending just beyond base, rarely one branch reaching 1/3 leaf length; alar cells differentiated, rectangular; laminal cells papillose, papillae minute, granular, cuticular, much more abundant on abaxial surface. : Specialized asexual reproduction absent. Sexual: condition dioicous; perichaetial leaves narrowly ovate- to oblong-lanceolate, apex acute to acuminate. Seta: dark red, reddish, or light brown. Capsule: inclined to pendulous, cylindric, arcuate or sometimes straight, wrinkled and contracted below mouth when dry; annulus 1- or 2-seriate, deciduous, cells large; operculum conic to rostrate; peristome double; exostome teeth with fine striations between lamellae proximally, papillose distally; endostome basal membrane rather high, segments broad, keeled, cilia 2 or 3, as long or nearly as long as segments. Calyptra: naked. Spores: globose to ovoid, smooth or minutely papillose. North America, Europe, Asia, Pacific Islands (Hawaii, New Guinea).
Species 2 (1 in the flora). Buckiella occurs in terrestrial habitats in temperate, boreal, and rarely tropical woods. Buckiella draytonii (Sullivant) Ireland is endemic to the Hawaiian Islands.
Plants: dark green to yellow-green, glossy or sometimes dull. Stems: 2–6(–8) cm, 0.5–4 mm wide across leafy stem. Leaves: 0.7–4 × (0.2–)0.4–2 mm; alar cells spheric, oval, quadrate, or rectangular, in 1–8 vertical rows, region triangular, or auriculate and oval; basal laminal cells shorter, broader than medial; medial cells 36–180 × 3–21 µm; apical cells often shorter. : Specialized asexual reproduction by 2–7-celled propagula borne on branched stalks in leaf axils or in clusters without stalks on abaxial leaf surface. Seta: yellow or orange to red-brown. Capsule: yellowish, orange-brown, reddish, light brown, or dark red when mature, oblong to ovoid, smooth to striate, often wrinkled at neck, often contracted below mouth when dry; annulus differentiated; endostome cilia 1–3, usually as long as segments or nearly so, nodulose, rarely rudimentary or absent. North America, Mexico, Central America, South America, Europe, Asia, Africa, Pacific Islands (New Guinea), Australia, Antarctica.
Species ca. 90 (6 in the flora). Plagiothecium is a genus of terrestrial habitats in coniferous and deciduous woods, on rotten logs, stumps, bases of trees, humus and soil, frequently overlying acidic cliffs and boulders, sometimes in swamps and marshes, in temperate, boreal and Arctic regions, and in the tropics at high elevations.