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(Polygonum persicaria), a plant of the family Polygonaceae. A perennial herb measuring 20–60 cm tall, lady’s thumb has lanceolate leaves whose upper surface is frequently marked with a dark spot. The flowers are in compact terminal racemes. In the USSR, lady’s thumb grows in the European part, the Caucasus, Middle Asia, Siberia, and the Far East. The plant is encountered in meadows and along riverbanks and the shores of lakes; it also grows as a weed in fields, orchards, and gardens. Lady’s thumb contains tannin, essential oil, pectin, flavone derivatives, vitamins C and K, and mucilage. A liquid extract of lady’s thumb is used medicinally as a mild laxative and as a hemostatic for hemorrhoidal and uterine bleeding.