Lupinus is well developed in western North America, whence (perhaps via cultivation) additional species are likely to spread, as has L. polyphyllus.
1. Flowers less than 8 mm long, on pedicels ca. 1–2.5 mm long; annual waif, perhaps not persisting in Michigan.
1. Flowers 10–15 mm long, on pedicels (4–) 5–9 mm long; perennial.
2. Leaflets of larger leaves 8–11, ca. (2–) 2.5–4.5 (–4.8) cm long, apex obtuse to rounded.
2. Leaflets of larger leaves 12–14, ca. 6–11 cm long, apex acute.
All species found in Lupinus
MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. December 5, 2019. https://michiganflora.net/genus.aspx?id=Lupinus.