Herb, annual, glabrous, to 25 cm tall; rhizome absent; stolon present. Leaves submersed, or emerged; emerged leaves pale green to green-brown, petiole terete, 1.2-9.5 x 0.04-0.08 cm, basal sheath 1 cm long, blade linear, 1-7.4 x 0.2-0.5 cm, margin entire, apex acute, base attenuate, basal lobes absent, veins 3-5, pellucid markings absent; submersed leaves pale green, sessile, blade linear, to 5 x ca. 0.2 cm, margin entire, apex acute, base tapering, veins 1-3, pellucid markings absent. Inflorescence umbelliform or rarely racemose, erect, with 1 or 2 whorls, overtopping leaves, not vegetatively proliferating, to 6 x to 8 cm; whorls with 4-6 flowers; peduncle terete, not winged, 12-40 x 0.1-0.2 mm; rachis, if present, between whorls terete, not winged; bracts shorter than pedicel subtended, united, connate half of length, coarse, deltoid, 2.8-4.9 x 1-2.1 mm, delicate, apex acute, not dilated basally; pedicels in flower and fruit spreading, cylindrical, 0.5-3 x 0.03-0.05 cm. Flowers 0.6-0.8 cm wide; sepals in flower and fruit slightly appressed, 2.5-2.9 mm, with 3-5 veins, not papillose; petals clawed, 2.5-4.1 x 1.5-3 mm, claw ca. 1 mm long; stamens 9, filaments ca. 0.5 mm long, anthers basifixed, ca. 1 mm long, apex obtuse; carpels 15-20. Fruit flattened, obovate, 0.8-1.5 x 0.8-1 mm, 0-3-ribbed, without keel, eglandular, beak lateral, erect, 0.1-0.2 mm long.
Guyana present, S Brazil present, northeastern U.S.A present
from northeastern U.S.A. to S Brazil; over 70 collections examined, including 4 from Guyana (GU: 4).
Sold as an aquarium plant under German commercial names of "Zartblättriger Froschlöffel" and "Kleinblättriger Froschlöffel", and English names "Pigmy chain-sword" and "Dwarf Amazonian Swordplant".