Rotala wallichii (Hook. fil.) Koehne

Herbs, perennial, to 30 cm, aquatic with emergent inflorescence, amphibious, or terrestrial. Stem solitary, rarely branched, slender. Leaves whorled; aerial leaves 3-12-whorled, linear to oblong, apex obtuse or 2-cleft; submerged leaves typically more numerous, filiform, distinctly longer than aerial leaves, 1.5-2.5 cm, apex 2-cleft. Bracts much reduced in inflorescence, oblong or ovate, 2-3 mm. Flowers 5-8-whorled per node, shortly pedicellate in a bracteate raceme; bracteoles short, less than 1/2 length of floral tube. Floral tube 4-merous, campanulate, translucent, ca. 1.5 mm; sepals 4; epicalyx absent. Petals 4, showy, light red or pink, orbicular, longer than floral tube. Stamens 4; anthers reaching margin of floral tube. Ovary globose, ca. 1 mm in diam.; style included, shorter than ovary. Capsules globose, ca. 1 mm in diam., 2-valved. Seeds ca. 0.7 mm. Fl. and fr. autumn and winter.

Ponds, wet places. Guangdong, Taiwan (Pingdong) [India, Indonesia, Malaysia, Myanmar, Thailand, Vietnam].

Hydrolythrum wallichii J. D. Hooker in Bentham & J. D. Hooker, Gen. Pl. 1: 777. 1867; Ammannia myriophylloides Dunn; A. wallichii (J. D. Hooker) S. Kurz.