Perennial herb with creeping or floating stems, to 60 cm long, rooting freely at nodes, sometimes with white, upward, spindle-shaped aerophores arising in clusters at the node of the floating stem; stems glabrous, branched, the tips ascending. Leaves narrowly elliptic to spatulate-oblong, 0.7-9.5 cm long, 0.4-2.7 cm wide, glabrous, the apex rounded or obtuse, margin entire, base narrowly cuneate or attenuate, the petioles 5-30 mm long. Flowers in leaf axils of ascending stems. Bracteoles deltoid, in pairs near the base of the ovary. Sepals 5, narrowly triangular- lanceolate, deciduous, 8-12 mm long, 1.6-2.5 mm wide, glabrous to hirtellous. Petals 5, pale yellow, broadly obovate, apex truncate or obtuse, sometimes semi-unfolded, base attenuate, 13- 18 mm long, 9-12 mm wide. Stamens 10, antesepalous stamens alternating with slightly shorter antepetalous stamens; anthers indehiscent or barely dehiscent, extrorse, 1.3-1.8 mm long, filaments 2-3.5 mm long. Pollen grains nearly always aborted, shriveled and unstainable. Disc with 5 depressed, V-shaped nectaries each fringed with dense, villous hairs. Style 5-7 mm long, glabrous; stigma discoid. Mature capsules lacking. 2 n= 24. Flowers May-Dec.

TAIPEI: Kuanyinshan, Kuo 4761. KEELUNG: Oldham s. n. 1864. TAOYUAN: Sasaki s. n. 1923. HSINCHU: Hukou, Peng 3215; Hsiangshan, Peng 6334. MIAOLI: Tonghsiao, Peng 5443; Yuanli, Peng 10575. TAICHUNG: by Chungcheng Park, Peng 10409; Tachiahsi, Kao 10054. NANTOU: Puli, DeVol 7502; Suili River, Peng 6556. CHIAYI: city park, Peng 6975. TAINAN: Peimen, Chiali, Morimoto 80. KAOHSIUNG: Doi 20; Henry s. n., s.d. PENGHU: Makung, Anchai, Peng 12755. PINGTUNG: Hengchun, Kawakami & Ito s. n. 1909. HUALIEN: Hsincheng, Chen s. n. 1981.

A natural triploid hybrid species between Ludwigia adscendens (L.) Hara, a tetraploid, and L. peploides (Kunth) Raven ssp. stipulacea (Ohwi) Raven, a diploid; the latter taxon does not occur in Taiwan. Widely distributed in southern China and throughout the lowlands of Taiwan, forming pure stands or mixed with other aquatic weeds in drainage ditches, fallow and wet paddies, along river banks, about waste swampy grounds and the borders of fish ponds or reservoirs.