Plants annual, 10-20(-70) dm; roots not also arising from proximal nodes. Stems scandent, ribbed, glabrous, often glaucous; prickles 0.5-1 mm. Leaves: ocrea green, plane to broadly funnelform, 9-14 mm, at least some foliaceous, base inflated or not, without prickles, margins oblique, eciliate, surface glabrous, glaucous; petiole 4.5-8 cm; blade triangular, 4-7 × 4.5-9 cm, base truncate to cordate, usually peltate, margins entire, sparsely retrorsely prickly, apex acuminate, faces glabrous, usually glaucous abaxially. Inflorescences capitate or spikelike, uninterrupted, 5-12 × 5-10 mm; peduncle 10-50 mm, retrorsely prickly; ocreolae overlapping, margins eciliate. Pedicels mostly ascending, 1-3 mm. Flowers 1-3 per ocreate fascicle; perianth greenish white, glabrous, accrescent, becoming fleshy and blue in fruit; tepals 5, connate to ca. 1/ 3 their length, broadly elliptic, 2-3.5 mm, apex acute to obtuse; stamens (6-)8, filaments distinct, free; anthers pinkish, ovate; styles 3, connate proximally. Achenes included, black or reddish black, spheroidal, 3-3.5 × 3-3.5 mm, shiny, smooth. Flowering Jun-Oct. Thickets, streams banks, pastures, forest edges, roadsides, railroad embankments, other moist, disturbed sites; 0-300 m; introduced; Conn., Del., D.C., Md., Miss., N.J., N.Y., Ohio, Oreg., Pa., R.I., Va., W.Va.; Asia. Persicaria perfoliata is an aggressive, fast-growing pest in its native range and in North America. At least some introductions appear to be through the nursery trade (J. C. Hickman and C. S. Hickman 1978; R. E. Riefener 1982). It was collected once in 1954 in British Columbia, but that population did not persist.
Annual, clambering and with reflexed-prickly stems and petioles as in the preceding 2 spp., climbing to several m; lvs thin, glabrous deltoid to hastate- cordate, shortly peltate at base, 3-8 cm, as wide as or wider than long, palmately or pinnipalmately veined; ocreae foliaceous-expanded; upper lvs represented only by the conspicuous, perfoliate ocreae; racemes spike-like, 1-2 cm, few-fld; stigmas 3; perianth 3-5 mm, persistent, thickening to form a fleshy, berry-like, iridescent-blue covering over the rotund-trigonous achene; 2n=24. Native of e. Asia, intr. and established in Pa., Md., and W.Va.; to be expected to spread.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.