Although undoubtedly related to the crus-galli group of thorns, this does not appear to have been found wild in N. America, although it has been suggested that a wild putative hybrid between crus-galli and macracantha is the same. This theory is supported by the shape of the nuts, which have hollows on the inner faces as in macracantha, only not so deep. Whatever its origin, C. prunifolia is one of the most admirable of all thorns. It is a tree up to 20 ft high, forming a rounded head of branches, wider than high, often reaching to the ground, and densely leafy; young shoots glabrous; spines rigid, sharp, 11⁄2 to 3 in. long. Leaves varying from roundish ovate or oval to obovate; 11⁄2 to 31⁄2 in. long, 11⁄2 to 21⁄2 in. wide; toothed nearly to the base, glabrous and brilliant dark green above; pale, dull and either glabrous or slightly downy on the midrib and veins beneath. The leaves turn a rich glowing crimson in autumn. Flowers 3⁄4 in. diameter, produced during June in rounded corymbs with hairy stalks; calyx-lobes glandular-toothed, not downy; stamens ten to fifteen, anthers pink. Fruit rich red, 5⁄8 in. long, globose, falling with the leaves in October. From crus-galli it is well distinguished by its wider leaves, hairy flower-stalks, and early falling fruit.
C. ovalifolia (Hornemann) DC., differs in the following respects from prunifolia: leaves somewhat downy on both surfaces; stamens fifteen to eighteen; but there are intermediate forms.
C. splendens Lodd. – Loudon makes this synonymous with C. crus-galli arbutifolia, a quite glabrous tree, whereas all the trees I have seen under the name of C. splendens are simply C. prunifolia as described above, i.e. with invariably downy flower-stalks, and leaves glabrous, except sometimes on the chief veins beneath.
In Dendroflora, No. 4 (1967), p. 27, H. J. Grootendorst points out that the thorn offered by some nurseries in the Netherlands as C. crus-galli ‘Splendens’ is a clone of C. prunifolia distinguished by its very broad crown (the specimens at Kew by the Rose Garden are narrow-crowned, with pendulous branches).