This globally threatened species occurs in s. Ill., w. Ky., c. Tenn., n. Miss. and n. Ala. It grows mostly in thin woods and edges with base-rich soils at the base of rocky slopes on Mississippian limestone, generally near streams, roads or field edges (Woods 2005). It has disappeared from some sites in the northern part of its range, but a few sites are clustered in or near the Land-Between-the-Lakes of Ky. (LYON, TRIG) and Tenn. (Stewart & Montgomery Cos.). It deserves to be cultivated and replanted for full recovery, and for its large edible tubers of possible ethnobotanical interest; these are 15-20 cm wide (Woods 2005). Recent management of some sites by KSNPC, USFS and others, with thinning of competing trees, has led to much improvement in vigor of the plants. Associated species of interest at Land-Between-the-Lakes and elsewhere include Arundinaria gigantea and, especially along trails, Tragia cordata. Without flowers or fruits, distinction from americana can be difficult; petioles are generally longer (ca. 6-8 cm versus 2-6 cm), and other leaf dimmensions tend to be larger (Woods 2005). Vines can grow up to 5-6 m high (as can americana), sometimes climbing up Arundinaria, with which it may have evolved.