Silphium integrifolium
Fl. Bor.-Amer. 2: 146. 1803.
Plants caulescent, 40–200 cm; fibrous rooted. Stems terete to slightly square, sparsely scabrous or glabrous (sometimes glaucous). Leaves: basal caducous; cauline opposite, sessile; blades lanceolate to ovate, 2–23 × 0.1–11 cm, bases round to caudate, margins finely serrate or entire, apices acute to acuminate, faces hispid, scabrous, or glabrous. Phyllaries 17–37 in 2–3 series, outer appressed, apices acute to acuminate, abaxial faces glabrous, hispid, pilose, or scabrous, sometimes stipitate-glandular. Ray florets 12–36; corollas yellow. Disc florets 70–225; corollas yellow. Cypselae 9–14 × 6–10 mm; pappi 1–4 mm.
Distribution
Ont., Ala., Ark., Ill., Ind., Iowa, Kans., Ky., La., Mich., Miss., Mo., N.Mex., Nebr., Okla., S.Dak., Tenn., Tex., Wis., Wyo.
Discussion
Varieties 2 (2 in flora).
Selected References
None.
Key
| 1 | Phyllaries: abaxial faces usually hispid, pilose, or scabrous, rarely glabrous; ray florets 12–22 | Silphium integrifolium var. integrifolium |
| 1 | Phyllaries: abaxial faces glabrous; ray florets 20–36+ | Silphium integrifolium var. laeve |