The may-tree, any species of Crataegus or the species Crataegus monogyna.
Crataegus monogyna, a hawthorn species native to Europe, northwest Africa and western Asia.
Ceanothus leucodermis, chaparral whitethorn, a shrub in the family Rhamnaceae.
Bursaria spinosa, a small Australian shrub.
Vachellia constricta, formerly Acacia constricta, whitethorn acacia, a shrub in the family Fabaceae.