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(Polygala senega), also senega snakeroot, a perennial herbaceous plant of the family Polygalaceae (milkwort). The stem reaches 25 cm in height. The leaves are alternate and lanceolate, and the small greenish or white flowers are in terminal racemose inflorescences. The senega root grows in forests in the temperate zone of North America. The plant is used in medicine. Extracts and decoctions of the roots, which contain saponins (mainly senegin), essential oil, and resin, are used as expectorants.