Type genus of the Rhamnaceae buckthorns

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Buckthorn \Buck"thorn`\, n. (Bot.) A genus ( Rhamnus ) of shrubs or trees. The shorter branches of some species terminate in long spines or thorns. See Rhamnus . Sea buckthorn , a plant of the genus Hippopha["e] .

Wiktionary Word definitions in Wiktionary
n. (context botany English) Any of the plants in the genus ''Rhamnus''; a buckthorn.

Wikipedia Word definitions in Wikipedia
Rhamnus is a genus of about 110 accepted species of shrubs or small trees , commonly known as buckthorns in the family Rhamnaceae . Its species range from 1 to 10 meters tall (rarely to 15 m) and are native mainly in east Asia and North America, but found ...