Plants 50-300 cm (weakly rhizomatous). Stems round. Basal leaves: blades ovate to narrowly lanceolate or lance-linear, to 30+ cm, margins usually entire. Cauline leaves: proximal petiolate, ovate to narrowly lanceolate or lance-linear, margins usually entire; distal sessile, smaller. Involucres 8-10 mm. Phyllaries (± purple-tinged) lance-ovate, midveins not winged (tips acute to acuminate, papillate). Corollas usually white or greenish, rarely purplish, 8-9(-10) mm. Cypselae fusiform or clavate, 4-5 mm (dark brown, 7-8-ribbed); pappi (5-)6-7.5 mm. 2n = 50, 52, 56.

Flowering (May-)Aug-Oct(-Dec). Wet, sandy woods, lowlands, savannas, roadsides; 0-300 m; Ala., Fla., Ga., La., Miss., N.C., S.C., Tex.

Arnoglossum ovatum is the most variable species in the genus (as implied by synonymy). Extreme forms (very narrow-leaved, e.g., Cacalia lanceolata form, and broadly ovate-leaved forms) look very distinctive; intergradations occur. Differences could be because of dysploid chromosome races, variances in habitat, or some unknown factors.