Annual herb 5-300 cm tall, often persisting and becoming woody at the base; young growth and inflorescence minutely puberulent; elongate pneumatophores arising from buried submerged roots. Leaves lanceolate, 1-9 cm long, 0.2-3 cm wide, narrowly cuneate at the base, the apex acuminate; submarginal vein not prominent; petioles 2.5-18 mm long. Sepals 4, lanceolate, 2-4 mm long, 0.7-1.2 mm wide, finely puberulent. Petals yellow, fading orange-yellow, elliptical, 2-3 mm long, 1-2 mm wide. Stamens 8, pale greenish-yellow, the epipetalous ones shorter; filaments of episepalous stamens 1-2 mm long, those of the epipetalous ones 0.5-1 mm long; anthers 0.4-0.6 mm wide; 0.2-0.3 mm high, shedding pollen directly onto the stigma at anthesis. Pollen grains shed individually. Disc slightly elevated, with a depressed ciliate nectary surrounding the base of each epipetalous stamen. Style pale greenish-yellow, 1-1.5 mm long; stigma depressed-globose, shallowly 4-lobed. Capsule relatively thin-walled, finely puberulent, 15-30 mm long, 1-1.2 mm thick, subterete, enlarged in the upper 1/6 to 1/3, subsessile. Lower seeds uniseriate in each locule of the capsule, nearly vertical, brown, oblong, 0.7-0.85 mm long, each firmly embedded in a cube of relatively hard endocarp; raphe about 1/3 the diameter of the body. Seeds in upper inflated portion of the capsule multiseriate, free, ovoid, 0.35-0.5 mm long. Lower part of capsule at first marked by distinct bumps corresponding to the position of the uniseriate seeds, but as the endocarp hardens and swells, the capsule becomes smooth. 2n = 16. Flowers Jun-Feb; fruit Jun-Feb.

TAIPEI: Nankang, Peng 7009; Hsintien, Peng 12212. ILAN: Tachou, Chao et al. 4965. TAOYUAN: Shanchuhu, Peng 13523; Lungtan, Peng 7216. HSINCHU: Yulo River, Peng 12138; Shanchiao, Peng 10404. MIAOLI: Tonghsiao, Peng 5440; Yuanli, Peng 11100. TAICHUNG: city, Peng 6338. TAINAN: Hsinhua, Peng 13289; Tungshan, Peng 8901. PINGTUNG: Wanchin, Peng 10136.

Pantropical weed of wet places at low elevations. Rather frequent in Taiwan.