Show Lower Taxa
Silphium radula
Trans. Amer. Philos. Soc., n. s. 7: 341. 1840.
Common names: Roughleaf rosinweed
Endemic
Plants caulescent, 30–250 cm; fibrous rooted. Stems terete, scabrous, hispid, or hirsute. Leaves: basal persistent or caducous, petiolate; cauline alternate or opposite, petiolate or sessile; blades lanceolate to ovate, 2–22 × 0.5–8 cm, bases attenuate to round, margins coarsely dentate or entire, apices acuminate to acute, faces scabrous, hispid, or hirsute. Phyllaries 18–37 in 2–4 series, outer appressed or reflexed, apices acute, abaxial faces scabrous. Ray florets 12–30+; corollas yellow. Disc florets 100–175; corollas yellow. Cypselae 10–17 × 7–15 mm; pappi 2–5 mm.
Distribution
Ark., Kans., La., Mo., Okla., Tex.
Discussion
Varieties 2 (2 in the flora).
Selected References
None.
Key
| 1 | Basal leaves caducous; ray florets 20–30+ | Silphium radula var. radula |
| 1 | Basal leaves persistent; ray florets 12–18 | Silphium radula var. gracile |