Ludwigia epilobioides Maxim.

The fine distinction found between typical Ludwigia epilobioides and subsp. greatexii in Japan is not apparent in other material of this species. The two taxa are therefore not separated in this treatment.

Young shoots of this species are sometimes used to feed farm animals.

Herbs erect, often stout, annual. Stems 15-130 cm tall, well-branched, subglabrous or finely puberulous. Petiole 3-15 mm; leaf blade narrowly elliptic to narrowly lanceolate, 1-10 × 0.4-2.5 cm, subglabrous or puberulous, lateral veins 8-13 per side, submarginal vein inconspicuous, base narrowly cuneate, apex acuminate. Sepals 4 or 5, rarely 6, deltate, 1.5-4.5 mm, puberulous. Petals yellow, obovate, 1.8-2 × 0.7-1.2 mm. Stamens as many as sepals; filaments 0.5-1.2 mm; anthers 0.4-0.7 mm; pollen in monads. Style 0.5-1.2 mm; stigma globose. Capsule light brown, sublinear and terete, 1-2.8 cm, 1-2 mm in diam., puberulous, relatively thinly walled, wall often detaching at maturity, leaving columns of seeds attached to vascular strands; subsessile. Seeds in 1 or 2 rows per locule, each locule loosely enclosed in a column of spongy, light brown endocarp that disintegrates easily into 1- or 2-seeded units, light brown with dark red-brown stripes, 0.8-1.4 mm, raphe inconspicuous. Fl. May-Aug, fr. Jun-Oct. 2n = 48*.

Anhui, Fujian, Guangdong, Guangxi, Guizhou, Hainan, Hebei, Heilongjiang, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Jilin, Liaoning, Nei Mongol, Shaanxi, Shandong, Shanxi, Sichuan, Taiwan, Yunnan, Zhejiang [Japan, Korea, Russia (Amur region), Vietnam].

Often common in low moist places such as paddy fields, ditches, steam banks; near sea level to 1600 m.

Jussiaea fauriei H. Léveillé; J. greatrexii H. Hara; J. japonica H. Léveillé; J. parmentieri H. Léveillé; J. philippiana H. Léveillé; J. prostrata var. fauriei (H. Léveillé) H. Léveillé; J. prostrata var. parmentieri (H. Léveillé) H. Léveillé; J. prostrata var. philippiana (H. Léveillé) H. Léveillé; Ludwigia epilobioides subsp. greatrexii (H. Hara) P. H. Raven; L. greatrexii (H. Hara) H. Hara; Nematopyxis japonica Miquel.