Plants 70-140 cm. Stems strongly ridged (glabrous or sparsely pubescent). Basal leaves: (petioles 10-45 cm) blades (with 3 main veins from bases) broadly ovate or elliptic, 12-15(-20) cm (bases cuneate, decurrent onto petioles), margins entire, sinuate, crenulate, or denticulate. Cauline leaves: proximal petiolate or sessile (mid stem sessile, bases broadly cuneate), blades narrowly ovate, margins entire, sinuate, crenulate, or denticulate; distal petiolate or sessile, smaller. Involucres (8-)9.5-10(-12) mm. Phyllaries (pale green) ovate, midvein wings uniform or highest at apices. Corollas white or greenish, sometimes tinged with purple, 7-8(-9.5) mm. Cypselae fusiform or clavate, 4 mm (dark brown, 6-8-ribbed); pappi 5-7 mm. 2n = 50.

Flowering Sep-Nov. Shaded, wet areas of hillside seepages, thickets, and swamps; of conservation concern; 0-100 m; Ala., Fla., Ga.

Arnoglossum sulcatum occurs in the Florida panhandle and adjacent Georgia and Alabama.