This tall woodland herb is widespread in eastern North America, except on the southeastern Coastal Plain (K, W). Before flowering, pallida in Ky. can usually be distinguished from capensis by the glaucous bloom on its young stems and upper leaf surfaces; also, the nodes tend to be more reddish, and the crenulations on leaves tend to be more rounded. I. pallida is reportedly pollinated by bumble-bees in general, while capensis may be largely dependent on humming-birds (as reviewed by Y); hybrids are unknown. Rare plants of pallida with creamy white flowers, named forma speciosa Jenn., have been observed by D. Dourson (pers. comm.) and JC along Indian Creek in MENI.