Polygonum beyrichianum Chamisso & Schlechtendal, Linnaea 3: 42. 1828; P. meisnerianum (Chamisso & Schlechtendal) M. Gómez var. beyrichianum (Chamisso & Schlechtendal) Meisner

Plants annual, 3-10 dm; roots not also arising from proximal nodes. Stems erect or scandent, ribbed, glabrous or pubescent with tufted hairs and glandular hairs; prickles 1-1.5 mm. Leaves: ocrea brownish, cylindric, 8-20 mm, chartaceous, base inflated or not, sometimes with prickles, margins oblique, eciliate or ciliate with bristles 0.2-0.5 mm, surface glabrous or, rarely, glandular-pubesent; petiole 0.1-0.5 cm, leaves sometimes sessile; blade usually linear-lanceolate to lanceolate, rarely hastate, 5.5-14 × 0.8-1.5 cm, base cordate to truncate or cuneate, margins entire or, rarely, hastate, ciliate, apex acuminate, faces abaxially and adaxially usually glabrous, rarely appressed-pubescent with eglandular hairs, sometimes also with glandular hairs, major veins retrorsely prickly. Inflorescences capitate or racemelike, uninterrupted, 4-15 × 3-8 mm; peduncle 10-80 mm, stipitate-glandular at least distally, often with retrorse prickles proximally; ocreolae overlapping, margins eciliate or ciliate with bristles to 0.5 mm. Pedicels mostly ascending, 2-3.5 mm. Flowers 2-3 per ocreate fascicle; perianth white to pink, glabrous, accrescent, not becoming blue and fleshy in fruit; tepals 5, connate ca. 1/ 2 their length, broadly elliptic to ovate, 2.3-3 mm, apex obtuse; stamens 5, filaments distinct, free; anthers yellow or pink, ovate; styles 3, connate to middle. Achenes included, dark brown to black, 3-gonous, 3-4 × 2-3 mm, shiny, smooth.

Flowering Jun-Oct. Swamps, wet ditches, thickets; 0-80 m; Fla., Ga., La., S.C., Tex.; Mexico; West Indies; Central America; South America; se Africa.