Polygonum perfoliatum seeds mature in Oct.杠板归 gang ban gui. Herbs annual. Stems trailing, red-brown, 0.8-2 m, branched, angulate, with retrorse prickles along angles. Petiole 3-8 cm, sparsely retrorsely prickly; leaf blade triangular-peltate, 4-6 × 5-8 cm, abaxially usually sparsely retrorsely prickly along veins, adaxially glabrous, base truncate or subcordate, apex subacute; ocrea tubular, with green herbaceous orbicular wing at apex, 1.5-3 cm in diam. Inflorescence terminal or axillary, spicate, 1-3 cm; bracts ovate-orbicular, each 2-4-flowered. Perianth white or pinkish, 5-parted; tepals elliptic, ca. 3 mm, in fruit dark blue, accrescent, fleshy. Stamens 8, in 2 whorls, included. Styles 3, connate at middle. Achenes included in persistent perianth, black, shiny, globose, 3-4 mm in diam. Fl. Jun-Aug, fr. Jul-Oct.