The Collaborative International Dictionary
Blackthorn \Black"thorn`\, n. (Bot.)
A spreading thorny shrub or small tree ( Prunus spinosa), with blackish bark, and bearing little black plums, which are called sloes; the sloe.
A species of Crat[ae]gus or hawthorn ( Crat[ae]gus tomentosa). Both are used for hedges.
Sloe \Sloe\ (sl[=o]), n. [OE. slo, AS. sl[=a]; akin to D. slee, G. schlehe, OHG. sl[=e]ha, Dan. slaaen, Sw. sl[*a]n, perhaps originally, that which blunts the teeth, or sets them on edge (cf. Slow); cf. Lith. slywa a plum, Russ. sliva.] (Bot.) A small, bitter, wild European plum, the fruit of the blackthorn ( Prunus spinosa); also, the tree itself.
Wikipedia
Prunus spinosa (blackthorn, or sloe) is a species of Prunus native to Europe, western Asia, and locally in northwest Africa. It is also locally naturalised in New Zealand and eastern North America.
Usage examples of "prunus spinosa".
Resembles the Blackthorn or Sloe (Prunus spinosa), but is less thorny and has straight, not crooked branches, covered by brown, not black bark, only a few of the old ones terminating in spines, the younger ones downy.