Isopterygium latebricola (Schimper) Delogne; Leskea latebricola (Schimper) Wilson; Plagiotheciella latebricola (Schimper) M. Fleischer

Plants in dense mats, light green to yellowish, glossy. Stems to 2 cm, 0.5-1 mm wide across leafy stem, prostrate to erect, ± complanate-foliate. Leaves erect-spreading, basally imbricate, ovate-lanceolate, symmetric, concave, 0.7-1.5 × 0.2-0.5 mm; margins plane or narrowly recurved nearly to apex, entire at apex or sometimes with few serrulations; apex acuminate, not abruptly contracted; costa ending just beyond leaf base, often ecostate; alar cells rectangular, 26-72 × 12-19µm, in 1-5 vertical rows, terminating in 1 cell at base, region triangular; medial laminal cells 52-150 × 4-10µm. Specialized asexual reproduction usually present as propagula, 57-108 × 7-14 µm, of 3-6 cells borne in leaf axils, or in clusters without stalks on abaxial leaf surface, or sometimes at leaf apices. Sexual condition dioicous, rarely fruiting. Seta light brown to orange-brown, 0.6-1 cm, straight. Capsule erect or rarely inclined, light brown to orange-brown when mature, straight or rarely somewhat arcuate, 0.5-1.2 × 0.2-0.6 mm, smooth, slightly wrinkled at neck when dry; operculum conic-apiculate to short-rostrate, 0.4-0.6 mm; endostome cilia absent, or 1 or 2, rudimentary. Spores 9-13 µm.

Capsules mature summer. Swamps, fens, marshes, inundated woods on rotten logs, stumps, base of trees, humus; low elevations (50-100 m); N.B., Nfld. and Labr. (Nfld.), N.S., Ont., Que.; Conn., Mass., Mich., Minn., N.J., N.Y., Ohio, Pa., Wis.; Europe.

Plagiothecium latebricola a rare species of northeastern North America, where it always occurs in wet habitats. The species is the smallest in the genus and is distinguished by short stems to 2 cm; erect-spreading, mostly symmetric, somewhat concave leaves 0.7-1.5 mm; medial laminal cells 4-10 µm wide; tapering decurrencies composed of rectangular cells; and erect, straight capsules that are not contracted below the mouth.