Cumberland Rosinweed

Plants caulescent, 65–200 cm; fibrous rooted. Stems terete, glabrous. Leaves: basal caducous; cauline opposite, petiolate; blades lanceolate, hastate, ovate, or sagittate, 1–24 × 0.5–18 cm, bases cuneate, or round (distal), or cordate, truncate, hastate, or sagittate (proximal), margins coarsely dentate or entire, apices acuminate to acute, faces sparsely hirsute, hispid, or scabrous. Phyllaries 11–15 in 2–3 series, outer reflexed or appressed, apices acute, abaxial faces scabrous. Ray florets 7–9; corollas yellow. Disc florets 20–40; corollas yellow. Cypselae 7–8 × 5–6 mm; pappi 0.5–1 mm. 2n = 14.

Silphium brachiatum is a species of flowering plant in the family Asteraceae known commonly as Cumberland rosinweed. It is a rare member of the genus Silphium and is native to the southern Cumberland Plateau where it is found in only a few counties of Alabama, Georgia, and Tennessee. It was described by Augustin Gattinger, the first state botanist of Tennessee.