Senecio plattensis Nutt.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Biennial or short-lived perennial 2–7 dm from a short caudex, sometimes also stoloniferous, ± persistently floccose-tomentose until flowering time or later, at least as to the stem, lower lf-surfaces, and invols; basal lvs narrowly or broadly elliptic or ovate to suborbicular or broadly oblanceolate, crenate-serrate or some deeply lobed, the blade and petiole to 10 × 3 cm; cauline lvs conspicuously reduced upwards, becoming sessile, ± pinnatifid; heads several or rather many, the disk 6–12 mm wide; invol 4–6 mm; achenes usually hirtellous; 2n=44, 46. Prairies and other dry, open places; Great Plains, and irregularly e. to s. O., Tenn., N.C., and Va., mostly inland from the coastal plain. May–July. Passes into nos. 6 [Senecio tomentosus Michx.] and 8 [Senecio pauperculus Michx.].