Whitethorn meaning : Crataegus monogyna, a hawthorn species native to Europe, northwest Africa and western Asia. Bursaria spinosa, a small Australian shrub. Vachellia constricta, formerly Acacia constricta, whitethorn acacia, a shrub in the family Fabaceae. Ceanothus leucodermis, chaparral whitethorn, a shrub in the family Rhamnaceae.