This northeastern species has been rarely reported from Ky. (M). Verified colls. (det. by J.B. Phipps) are known only from BATH (GH: Horsey #1781, Olympia) and OLDH (DHL: H. Woodward #2999, field on Old Zaring Rd. to the Univ. of Lousiville Farm). However, Ky. was not included in the range for succulenta provided by FNA 9. This species is distinguished from calpodendron as follows (FNA 9): new growth glabrous (versus pubescent); thorns on twigs usually numerous (versus often absent); leaves often blue-green, with impressed venation (versus often yellowish green, without impressed nerves), upper surfaces usually glabrous (versus persistently appressed-pubescent); sepal margins glandular-serrate to glandular-laciniate (versus nearly entire or shallowly glandular-serrate); anthesis 1-3 weeks earlier. It is reportedly triploid; the closely related, more widespread northern species, C. macracantha Loddiges ex Loudon is tetraploid (FNA 9).