Ipomoea batatas (L.) Lam. is the cultivated sweet-potato (often called “yam,” a name more strictly applying to the monocot genus Dioscorea).
1. Corolla salverform, red, with stamens and pistil conspicuously exserted; sepals with subulate subterminal appendages; leaves deeply and ± palmately divided into narrow lanceolate segments.
1. Corolla funnelform, blue to purple or white, with stamens and pistil shorter; sepals various; leaves not divided or only broadly 3–5-lobed.
2. Stems glabrous or nearly so; sepals obtuse to rounded, at most hispidulous toward margin beneath (more uniformly hispidulous above).
2. Stems pubescent; sepals acute or acuminate, with long stiff hairs beneath, especially toward base.
3. Calyx ca. 17–25 mm long, the sepal lobes narrowed to prolonged linear-acuminate tips; peduncles rarely as long as calyx (flowers often nearly sessile).
3. Calyx ca. 11–15 (–16) mm long, the sepal lobes ± oblong and acute; peduncles longer than the calyx.
All species found in Ipomoea
MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. December 10, 2017. http://www.michiganflora.net/genus.aspx?id=Ipomoea.