Large-root morning glory

Perennials, root relatively large, tuberlike. Stems trailing or twining. Leaf blades ovate, triangular-ovate, or 3-lobed, 50–150 × 50–150 mm, base cordate to sagittate or truncate, margins ± crenulate, surfaces: abaxial tomentulose, adaxial gla­brous, minutely beaded along veinlets. Peduncles tomentulose. Flowers noc­turnal; sepals oblong-elliptic, 16–18 mm, coriaceous, sericeous; corolla white, throat lavender to purple inside, salverform, 50–80 mm.

Flowering Jun–Jul. Beaches, clearings, dunes; 0–40 m; Ala., Fla., Ga., Miss., N.C., S.C.

Ipomoea macrorhiza has been confused with the Mexican and Central American I. jalapa (Linnaeus) Pursh; I. macrorhiza differs by having nocturnal, moth-pollinated flowers with white corollas versus matinal, bee-pollinated flowers with lavender corollas.