Poplar species differ from willow species by having notched or fringed bracts. Buds are covered by several scales, and the number of stamens ranges from 3 to 30. The black poplar is a tall tree with thick bark, triangular-ovate to rhombic-ovate leaves. The buds are elongated-ovate, large, sticky, and fragrant. It grows in the southern regions of the European part of Russia, the Caucasus, Central Asia, and is often cultivated in gardens.
In early spring, swelling but unopened poplar buds (Gemmae Populi) are collected. They contain resin, essential oil, glycosides such as salicin and populin (a benzoyl-salicin derivative), and tannins. They were used as a tincture for their anti-inflammatory properties and are included in the composition of Black Riga Balsam.
An extract in the form of an ointment was used for rubbing into joints to relieve pain. Experiments have demonstrated the bactericidal properties of the poplar bud tincture.