Rhamnus \Rham"nus\, n. [NL., from Gr. "ra`mnos a kind of prickly shrub; cf. L. rhamnos.]

(Bot.) A genus of shrubs and small trees; buckthorn. The California Rhamnus Purshianus and the European R. catharticus are used in medicine. The latter is used for hedges.

Source: Webster's Revised Unabridged Dictionary (1913)
 

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].

Source: Webster's Revised Unabridged Dictionary (1913)