Shui Ding Xiang

Shui Ding Xiang is the whole herb of Ludwigia adscendens (Onagraceae), a perennial aquatic or amphibious plant of ponds, ditches and slow streams across tropical and subtropical Asia. Stems are creeping or floating, 30–100 cm long, rooting at the nodes and bearing conspicuous spongy white pneumatophore floats at submerged nodes. Leaves are alternate, oblanceolate to elliptic, 2–6 cm long, glabrous, with rounded apex and tapering base. Solitary axillary flowers stand on slender pedicels and bear five obovate creamy-white petals 8–14 mm long with a yellow basal blotch, surrounding ten stamens and a five-locular inferior ovary. The capsular fruit is cylindrical, 1.5–2.5 cm long, splitting irregularly to release numerous small seeds.