Fronds ovoid, 0.4--0.8 mm (x 0.3--0.5 mm), 1.3--2 times as long as wide, 1--1.5 times as deep as wide, rounded or slightly pointed at apex, papilla absent; adaxial surface transparently green, with 1--10(--30) stomates; pigment cells absent in vegetative tissue. 2n = 30, 60.

Flowering (very rare) late spring--fall. Mesotrophic to eutrophic, quiet waters in warm-temperate to tropical regions with mild winters; 0--600 m; probably introduced; Calif., Fla.; South America (Colombia, Ecuador); e Asia; Pacific Islands (Hawaii).