This is widely scattered in Appalachian and Atlantic Coastal regions, but with disjunct localities west to the Ozarks. It usually grows in sandy streambeds and oxbows that can dry out in summer. Variation needs further study (W). Some material in Ky. may be at least transitional to the broadly Appalachian I. valida (Engelm.) Clute (= I. engelmannii var. caroliniana A.A. Eat.); see notes under that name.