Hypnum vesiculare Schwagrichen, Sp. Musc. Frond. Suppl. 2(2,2): 167, plate 199 [bottom]. 1827; Ectropothecium vesiculare (Schwagrichen) Mitten; Vesicularia caloosiensis (Austin) H. A. Crum

Stems with branches horizontal, somewhat flattened, simple; epidermal cells in 2-4 rows, walls thick, inner cells larger, walls thick, central strand cell walls thin. Leaves somewhat contorted when dry, plane, sometimes falcate-secund; ventral branch leaves ovate to oblong-ovate, 1.1 mm; apex apiculate to acuminate; alar cells not or slightly differentiated; basal laminal cells more elongate than distal cells; distal cells lax, hexagonal to oblong-rhomboidal, 2.5-5:1, walls thick to thin; dorsal and lateral branch leaves ovate, broadly oblong-ovate, or ovate-lanceolate, 1.1 mm; apex acute to acuminate; basal laminal cells more elongate than distal cells; distal cells hexagonal, oblong-hexagonal to somewhat rhomboidal, 2.3-4.1:1, walls usually thick; marginal cells noticeably narrower. Seta 1.3-2.1 cm, flexuose, curved just below capsule. Capsule 0.9 mm; exothecial cells quadrate to rectangular, walls thin, often collenchymatous; stomata at extreme base of capsule; exostome teeth brown.

Capsule maturity unknown. Shaded, moist soil, humus, logs, rock, submerged rock in running water; low elevations; Fla., La.; Mexico; Central America; South America.

Vesicularia vesicularis has been introduced in greenhouses, for example, at the Missouri Botanical Garden Climatron©, and on sides of goldfish pools in California.