Coefficient of Conservatism:
Coefficient of Wetness:
R. W. Smith
Forests of diverse sorts, borders of forests, river banks and floodplains, lake shores, ravines, thickets, hillsides, rocky openings; roadsides, fencerows, fields.
A striking species with very long thorns, to nearly 10 cm in some specimens. Two varieties, often recognized as species, occur in Michigan: var. succulenta (stamens ca. 20, anthers ca. 0.4–0.8 mm long) and var. macracantha (Loud.) Eggl. (stamens ca. 10, anthers ca. 1–1.2 mm long). Var. macracantha is widespread, from the Upper Peninsula into southern Michigan, and var. succulenta is only in the Lower Peninsula.