Bryum exile Dozy & Molkenboer, Ann. Sci. Nat., Bot., ser. 3, 2: 300. 1844; Brachymenium exile (Dozy & Molkenboer) Bosch & Sande Lacoste

Plants green to yellow-green. Stems 0.5-1(-2) cm, slender, stringlike when dry, evenly foliate. Leaves folded adaxially along costa around stem when dry, ovate, weakly to strongly concave, 0.4-1(-1.5) mm; margins plane; apex broadly acute-rounded; costa percurrent to short-excurrent, apiculus occasionally present; proximal laminal cells abruptly quadrate, 1:1; medial and distal cells 8-12(-14)µm wide, (3-)4-5:1. Specialized asexual reproduction by leaf axil bulbils, bulbils 1 or 2 per axil, rounded, 200-750 µm, primordia present, leafy, arising from near base or mid bulbil, and by rhizoidal tubers, brown, spheric, 100-200 µm, cells smooth. [Capsule erect, red-brown, 1-2(-3) mm; hypophysis thick, rugose; peristome strongly reduced; endostome not or occasionally partly adherent to exostome, basal membrane low, segments reduced, split, perforations absent, cilia absent].

Concrete, rock; low elevations (0-10 m); Fla., N.Mex.; West Indies; Central America; South America; se Asia; Africa; Pacific Islands; Australia.

Gemmabryum exile is one of the most distinctive and easily identified species in the genus, with very slender stringlike stems and small infolded leaves that are ovate with plane margins.