Ludwigia adscendens (L.) Hara

The plant is used medicinally for its febrifugal and antiswelling properties.

Herbs perennial, with creeping or floating stems, rooting at nodes, with white, erect, short (1-3 cm), spindle-shaped pneumatophores in clusters at nodes of floating stems. Floating stems to 400 cm, terrestrial stems 20-60 cm, much branched, tips ascending, glabrous or densely villous. Petiole 5-20 mm; leaf blade oblong to spatulate-oblong, 0.4-7 × 0.7-3 cm, glabrous, lateral veins 6-13 per side, submarginal vein not prominent, base narrowly cuneate or attenuate, margin entire, apex obtuse to subacute. Sepals 5, deltoid-acuminate, 5-11 mm, glabrous or villous. Petals creamy-white with yellow base, obovate, 9-18 × 6-10 mm. Stamens 10; filaments white, 2.5-4 mm; anthers 0.7-1.8 mm; pollen in monads. Style white, 4-10 mm, glabrous; stigma discoid. Capsule light brown with dark brown ribs, cylindric, terete, 1.2-2.7 cm, 3-4 mm in diam., glabrous or villous, thickly walled, tardily and irregularly dehiscent; pedicel 1.5-5.5 cm. Seeds in one row per locule, firmly embedded in coherent cubes of woody endocarp fused to capsule wall, pale brown, oblong or elliptic, 1.1-1.3 mm, raphe inconspicuous. Fl. Apr-Nov, fr. May-Nov. 2n = 32*.

Subtropical Himalaya, India, east to China, Malaysia, Australia.

Fujian, Guangdong, Guangxi, Hainan, Hunan, Jiangxi, Taiwan, Yunnan, Zhejiang [India, Indonesia, Japan, Malaysia, Nepal, Pakistan, Philippines, Sri Lanka, Thailand; widespread in Africa, S and SE Asia, Australia].

200-600 m

Wet swampy places, flooded rice paddies, often floating in water at edges of ponds, tanks, ditches; near sea level to 1600 m.

Jussiaea adscendens Linnaeus, Syst. Nat., ed. 12, 2: 297; Mant. Pl. 1: 69. 1767; J. repens Linnaeus.

Ludwigia adscendens, the water primrose, is a species of flowering plant in the evening primrose family. Its native distribution is unclear. It is now a common weed of rice paddies in Asia and occurs also in Australia and Africa, but may have originated in South America.

This plant is a perennial floating herb with white spongy buoys, and can float on water surface as well as creep over the surface of wetlands. The plant has simple leaves with elliptic blades, which are 0.4–7 cm long and 0.7–3 cm wide. Its petioles are 0.5–1.0 cm short. Its cream flowers emerge singly at axils, and each have 5 sepals, 5 petals, and 10 stamens.