Cacalia floridana A. Gray, Proc. Amer. Acad. Arts 19: 52. 1883; Conophora floridana (A. Gray) Nieuwland; Mesadenia floridana (A. Gray) Greene

Plants to 100 cm (weakly rhizomatous). Stems 5-ribbed. Basal leaves: blades (usually with 5 main veins from bases) ovate to elliptic, to 18 cm, margins entire. Cauline leaves: proximal petiolate, ovate, margins crenulate; distal petiolate or sessile, smaller. Involucres 12–15 mm. Phyllaries (light green) ovate, midvein wings uniform or highest at apices. Corollas white or light green, (9–)11–12 mm. Cypselae fusiform, 5 mm (green); pappi 7–8.5 mm. 2n = 50, 52.

Flowering May–Jul. Dry sand ridges, pine-oak woodlands; of conservation concern; 0–20+ m; Fla.

Arnoglossum floridanum is known only from central peninsular Florida.