Bian Xu

Herba Polygoni Avicularis (Bianxu) Common Knotgrass Herb Common Knotgrass Herb is the dried aerial part of Polygonum aviculare L. (Fam. Polygonaceae). The drug is collected in summer when the leaves are growing luxuriantly, removed from the roots and foreign matter, and dried in the sun. Description Stems cylindrical and somewhat flattened, branched, 15-40 cm long, 2-3 mm in diameter. Externally greyish-green or brownish-red, with fine and slightly prominent longitudinal striations; nodes slightly swollen, with pale brown membranous stipulate sheaths, internodes about 3 cm long; texture hard, easily broken, fracture with a white pith. Leaves alternate, almost sessile or short petioled; lamina frequently fallen off, crumpled or broken, when whole, lanceolate, margin entire, both surfaces brownish-green or greyish-green. Odourless; taste, slightly bitter. Identification (1) Powder: Greyish-green. The epidermal cells on both surfaces of leaf with almost straight anticlinal and striated pe