Polygonum perfoliatum

Species: Polygonum perfoliatum

English Name: Spiny Knotweed

Chinese Name: 杠板歸

Family: Polygonaceae

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.

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– Wu ZY, Raven PH, Hong DY (eds) (2003). Flora of China, Volume 5: Ulmaceae through Basellaceae. Science Press, Beijing, and Missouri Bot Garden Press, St. Louis