Tall Jacob's-ladder, Tall Jacob's Ladder: Polemonium acutiflorum (Synonym: Polemonium caeruleum ssp. villosum)
Northern Jacob's-ladder, Northern Jacob's Ladder: Polemonium boreale ssp. boreale (Synonyms: Polemonium boreale ssp. richardsonii, Polemonium boreale var. villosissimum)
Jacob's-ladder: Polemonium pulcherrimum (ssp. lindleyi or ssp. pulcherrimum ?)