Plants: small to large, in dense mats. Stems: creeping, branches ascending to erect. Leaves: strongly crisped and inrolled, rarely erect-appressed when dry, erect-spreading to squarrose-recurved when moist, lanceolate to ligulate-lanceolate, not rugose; margins entire to crenulate; apex sharply acute, obtuse, or obtusely apiculate; costa percurrent to excurrent; basal laminal cells rectangular to elongate-linear; distal cells irregularly hexagonal to rounded-elliptic, 7–11 µm, in vertical rows, smooth to papillose or mammillose only over lumina, papillae 1 to many, conic; marginal cells not distinct from basal. Sexual: condition autoicous; perichaetial leaves similar to stem leaves. Seta: 5–12 mm. Capsule: exserted, ovate, narrowly ovate to ovate-oblong when old and dry, plicate below mouth; stomata superficial; peristome single; exostome teeth 16, sparsely striate. Calyptra: mitrate, lacerate, basal lobes many, smooth, naked or hairs few, plicate, covering entire capsule. Spores: isosporous or anisosporous, unicellular. se United States, Mexico, West Indies, Central America, South America, Asia, Africa, Australia.
Species ca. 460 (1 in the flora). Distinguishing characters for Macromitrium include prostrate creeping stems with many short, erect branches, terminal sporophytes, a mitrate, plicate calyptra, and a propensity for a chestnut brown color.