Both of our species are natives of Eurasia, rarely escaped from cultivation.
1. Calyx cleft nearly to the base, the lobes at least 7 mm long and narrowly linear-attenuate.
1. Calyx cleft about half to 2/3 to the base, the lobes ca. 2–5 mm long and narrowly lanceolate to triangular.
All species found in Anchusa
MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. May 16, 2022. https://michiganflora.net/genus.aspx?id=Anchusa.