Polemonium

1. Leaflets lance-elliptic (often 2–4 times as long as broad), 19 or more on lower leaves; fruit sessile.

P. caeruleum

1. Leaflets ovate to lance-elliptic (often less than twice as long as broad, but sometimes narrower), 17 or fewer; fruit short-stalked.

P. reptans

All species found in Polemonium

Polemonium caeruleumGREEK-VALERIAN 
Polemonium reptansJACOB'S-LADDER 

Citation:

MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. November 24, 2017. http://michiganflora.net/genus.aspx?id=Polemonium.