Kingdom: Plantae

Phylum: Streptophyta

Class: Equisetopsida

Subclass: Magnoliidae

Order: Caryophyllales

Family: Polygonaceae

Genus: Persicaria

Species: glabratum

Description: Denseflower Knotweed is an annual or perennial herbs with red, ascending, swollen stems, often rooting at the nodes, 5-15 cm long, not hairy. Leaves are oblong-lanceolate to narrowly lanceolate, 14-28 cm long, 3-6 cm wide, minutely pustulate, otherwise usually smooth, sometimes with scattered hairs on nerves of lower surface, leaf stalk 0.5-2 cm long, ocreae tubular, usually 20-30 mm long, apex not ciliate, sometimes with a few small bristles ca. 0.5 mm long. Flowers in open racemes, sometimes in paniculate inflorescences 5-10 cm long, each flower on a jointed pedicel; tepals white or pinkish, 3-4 mm long, sometimes sparsely so, glandular punctate. Nuts dark brown to nearly back, broadly ovoid, biconvex or subtrigonous, 2-2.5 mm long, the surface glossy. Denseflower Knotweed is native to South America, parts of Africa and Tropical & Subtropical Asia. In India it is seen in the Western Ghats and the Himalayas upto altitudes of 2100 m.

Uses: pure anthelmintic substance (PGA) has been isolated from the methanol-aqueous extract of the leaf of Polygonum glabrum Willd., a semi-aquatic Sudanese species of the family Polygonaceae. The antiparasitic in-vitro activity of several fractions isolated from the plant, has been examined comparatively with that of PGA. PGA also showed molluscicidal activity against Biomphalaria glabrata and Limnea truncatula Müll. Structural determination of PGA was attempted following data analysis of UV, IR, 13C NMR, 1H NMR and MS spectra and suggests that PGA is a terpenoid.