Ludwigia perennis L.

Herbs erect, annual, with taproot. Stems 20-100 cm tall, branched, subglabrous or minutely puberulous on younger parts. Petiole 2-15 mm, winged; leaf blade narrowly elliptic to lanceolate, 1-11 × 0.3-2.7 cm, lateral veins 6-12 per side, submarginal vein inconspicuous, base narrowly cuneate, apex subacute. Sepals 4, rarely 5, deltate, (1.3-)2-3.5 mm, glabrous or minutely puberulous. Petals yellow, elliptic, 1-3 × 0.7-2 mm. Stamens as many as sepals, or rarely more; filaments 0.3-0.7 mm; anthers 0.5-0.7 mm; pollen in tetrads. Style 0.7-1.5 mm; stigma globose. Capsule often nodding, pale brown, oblanceoloid, terete, 3-16(-19) mm, 2.5-5 mm in diam., thinly walled, readily and irregularly loculicidal, glabrous or puberulous, sessile or pedicel to 6 mm. Seeds in 2 or more rows per locule, free, brown with fine brown lines, 0.3-0.5 mm, raphe very narrow and inconspicuous. Fl. and fr. Jul-Nov. 2n = 16.

Annual herb up to 1 m tall, subglabrous or minutely puberulent on younger parts. Leaves narrowly elliptical to lanceolate, 1-11 x 0.3-2.7 cm, narrowly cuneate at base, the apex subacute, with petioles 2-15 mm long, winged. Sepals 4(-rarely 5), deltoid, 2-3.5 x 0.7-1.8 mm, glabrous or minutely puberulent. Petals yellow, elliptical, 1-3 x 0.7-2 mm. Stamens as many as sepals, rarely more. Pollen shed in tetrads. Style 0.7-1.5 mm long. Capsules thin-valled, glabrous or puberulent, 3-16(-19) mm long, terete, readily and irregularly loculicidal, sessile or on a pedicel up to 6 mm long, often more or less nodding. Seeds pluriseriate in each locule of the capsule, free, brown with fine brown lines, ellipsoid-rounded, 0.3-0.5 x 0.2-0.25 mm, with narrow, inconspicuous raphe. Gametic chromosome number, n = 8.

Africa, Afghanistan, India, east to S. Japan, Malaysia, Australia, New Caledonia.

Fujian, Guangdong, Guangxi, Hainan, Jiangxi, Taiwan, Yunnan [Bangladesh, Bhutan, India, Indonesia, Japan, Myanmar, Nepal, Philippines, Sri Lanka; Africa (including Madagascar), SE and SW Asia, Australia, Pacific islands (New Caledonia)].

Distribution: Africa, tropical and subtropical Asia, China, through Malesia to tropical Australia and New Caledonia. Rare in Pakistan, in wet places, from sea level to 1000 m. Fl. Per.: Jul-Aug.

200-1400 m

Wet sites such as flood plains, roadside ditches, muddy wallows, abandoned rice paddies; near sea level to 1200 m.

Jussiaea caryophyllea Lamarck; J. perennis (Linnaeus) Brenan; Ludwigia caryophyllea (Lamarck) Merrill & F. P. Metcalf; L. parviflora Roxburgh.

Ludwigia parviflora Roxb., Hort. Beng. 11. 1814 (nomen); Fl. Ind. 1: 440. 1820; Boiss., Fl. Or. 2: 752. 1872; Clarke in Hook. f., Fl. Brit. Ind. 2: 588. 1879. Jussiaea perennis (Linn.) Brenan, Kew Bull. 8: 163. 1953.