This occurs mostly in mesic woods on base-rich soils in eastern states, except the southeastern Coastal Plain. Compared to perfoliata (FNA 26), grandiflora has leaves minutely pubescent on veins below (versus glabrous) but flowers smooth within (versus granular-pubescent). Also, there is usually just one leaf below the lowest branch (versus 2-4). Flowers are usually deep orange-yellow (versus paler stramineous yellow, and capsules lobes have truncate beaks (versus attenuate).