The Collaborative International Dictionary
Rhamnaceous
Rhamnaceous \Rham*na"ceous\, a. (Bot.) Of or pertaining to a natural order of shrubs and trees ( Rhamnace[ae], or Rhamne[ae]) of which the buckthorn ( Rhamnus) is the type. It includes also the New Jersey tea, the supple-jack, and one of the plants called lotus ( Zizyphus).
Wiktionary
rhamnaceous
a. Of or pertaining to plants in the family Rhamnaceae, the buckthorns.