Herbs erect, annual, sometimes woody at base and perennial, often in water and then with elongate pneumatophores on submerged branches. Stems 50-300 cm tall, branched, new growth and inflorescence minutely puberulous. Petiole 3-18 mm; leaf blade lanceolate, 2-9 × 0.5-2 cm, subglabrous or puberulous, lateral veins 7-15 per side, submarginal vein inconspicuous, base narrowly cuneate, apex acuminate. Sepals 4, lanceolate, 2-4 mm, finely puberulous. Petals yellow, fading to orange-yellow, elliptic, 2-3 × 1-2 mm. Stamens 2 × as many as sepals; anthers 0.4-0.6 mm; pollen in monads. Style 1-1.5 mm; stigma depressed-globose. Capsule cylindric, subterete, enlarged in upper 1/6-1/3, 1.5-3 cm, finely puberulous, relatively thinly walled; subsessile. Seeds in inflated upper capsule in 2 or more rows per locule, free, pale brown, ovoid, 0.3-0.5 mm, raphe narrow; seeds in lower capsule in one row per locule, embedded in cube of relatively hard endocarp, brown, 0.7-0.9 mm, raphe ca. 1/3 width of seed. Fl. and fr. Jun-Feb. 2n = 16*.

Africa, Tropical Himalaya, India, east to Taiwan, Malaysia, N. Australia, Polynesia, Tropical America.

Fujian, Guangdong, Guangxi, Hainan, Taiwan, Yunnan [Bangladesh, Bhutan, India, Indonesia, Malaysia, Myanmar, Nepal, Philippines, Singapore, Sri Lanka, Thailand, Vietnam; widespread in Africa, SE Asia, Australia, Pacific islands, South America].

200-500 m

Scattered to common in open wet often disturbed areas, streamsides, roadside ditches, clear agricultural land, or openings in moist forests; near sea level to 800 m.

Jussiaea hyssopifolia G. Don, Gen. Hist. 2: 693. 1832; J. linifolia Vahl; J. micrantha Kunze; Ludwigia micrantha (Kunze) H. Hara.

Ludwigia hyssopifolia, called seedbox and linear leaf water primrose, is a species of flowering plant in the genus Ludwigia, native to the New World Tropics and widely introduced to the rest of the world's tropics. A serious weed of rice paddies, a single plant can produce 250,000 seeds.