Please try our next iteration of the Michigan Flora Online here. Beginning on February 1, 2023, michiganflora.net will point to this new site.

The new site offers several benefits over the existing website, including real coordinate mapping, giving a clearer view of the density of documentation as well as more precision about plant distributions and their link to landforms. We will also have the ability to update species pages more regularly, both in terms of new collections and as more existing Michigan specimens are georeferenced. In addition, we have a better photo display, and offer indented keys.

R. W. Smith

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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.

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