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