Alternanthera polygonoides sensu Standley
Perennial herb with a stout vertical rootstock, mat-forming with numerous prostrate branches which root at the nodes, mats to c. 80 cm across. Branches ± white-villous when young (especially at the upper nodes), finally glabrescent and yellowish or reddish, striate. Leaves moderately white-villous when young but finally glabrescent on the upper surface and thinly hairy below, 8-43 x 2-12 mm, the elliptic, oval or obovate lamina obtuse or subacute at the apex, narrowed below into a long, indistinctly demarcated petiole which in the larger leaves almost equals the lamina in length. Inflorescences sessile, axillary, solitary or 2-3 together, ± globose or finally ovoid, 4-8 mm in diameter; bracts firm, membranous, white, ovate-acuminate, mucronate with the ex-current midrib, c. 2.75 mm, bracteoles similar but smaller and slightly narrower, c. 2.5 mm, falling with the fruit. Tepals white, subequal, oblong-lanceolate, acute, the outer two 3-4.5 mm, the inner three 2.5-4 mm, all prominently 3-nerved to about the middle and darker in the nerved area, mucronate with the excurrent midrib, ± pilose in the lower half with patent, white, minutely barbellate hairs. Stamens 5, all fertile, at anthesis slightly exceeding the ovary and style, the alternating pseudostaminodes much shorter than the filaments, oblong, dentate about the apex. Ovary compressed, narrowed below; style very short, broader than long. Fruit compressed, narrowed below; style very short, broader than long. Fruit compressed, orbicular-obcordate, c. 1.75-2 mm, seed discoid, c. 1.25 mm, brownish, shining, faintly reticulate.
Type: roadside near the sea, Rio de Janeiro, Brazil, St. Hilaire 223 (P, holotype!).
Distribution: A native of tropical America from Mexico and the West Indies south to Brazil, becoming widespread as an introduced weed in India, Java and other parts of the Old World tropics.
On sandy clay or sandy loam, habitat not noted in Pakistan; elsewhere usually on flat, rather bare ground, not infrequently where subject to periodi¬cal inundation.