Description from Flora of China
Achyranthes repens Linnaeus; Alternanthera repens (Linnaeus) Link.
Herbs annual. Stem diffuse, creeping, much branched, 20-30 cm tall, densely rigidly hairy. Petiole 3-10 mm, glabrous or hairy; leaf blade ovate, obovate, or elliptic-obovate, 1.5-4.5 × 0.5-1.5 cm, unequal in each pair, glabrous or annexed pilose, base acuminate, apex obtuse. Heads sessile, 1-3, axillary, white, globose or oblong, 5-10 mm. Bracts lanceolate, ca. 4 mm, spiny at apex; bracteoles lanceolate, 3-4 mm, apex acuminate, without spines. Tepals unequal, outer 2 lanceolate, ca. 5 mm, 3-veined below, rigid after anthesis, midvein stretching into spines; central segment elliptic, 3-3.5 mm, compressed; inner 2 small, enclosing ovary. Stamens 5; filaments 0.5-0.8 mm; pseudostaminodes shorter than filaments, entire or irregularly dentate. Style very short. Utricles brown, broadly ellipsoid, 1-1.5 mm. Fl. May, fr. Jul.
One of us (Clemants) notes that the name Alternanthera pungens has been misapplied here and that this taxon should instead be treated as A. caracasana Humboldt et al.
Roadsides. Fujian, Sichuan [native to South America; naturalized in Bhutan, Myanmar, Thailand, ?other parts of Indo-China, Australia, and United States].