Silphium mohrii

Plants caulescent, 40-160 cm; fibrous rooted. Stems terete, shaggy-hispid. Leaves: basal persistent, petiolate; cauline usually alternate, sometimes opposite, petiolate or sessile; blades lanceolate to narrowly ovate, 1.5-26 × 0.5-14 cm, bases attenuate to acute, margins coarsely toothed or entire, apices acuminate, faces shaggy-hispid. Phyllaries 14-19 in 2-3 series, outer appressed, apices acuminate to acute, abaxial faces shaggy-hispid. Ray florets 10-20; corollas pale yellow. Disc florets 40-85; corollas pale yellow. Cypselae 6-10 × 4-7 mm; pappi 1-2 mm.

Flowering late summer-early fall. Prairies, clearings, fence rows, sandy soils; 100-400 m; Ala., Ga., Tenn.

Fibrous-rooted from a short rhizome or crown, 6-15 dm, copiously shaggy-hispid, many or most of the hairs of the stem over 2 (to 5) mm; lvs alternate, opposite, or in part ternate, entire or toothed, the basal and lower cauline ones well developed and persistent, with broadly ovate to merely lanceolate, basally rounded or abruptly contracted blade 12-30 נ3-20 cm on a petiole 5-20 cm; cauline lvs progressively reduced upwards, becoming sessile, often ovate; heads several or rather numerous, with ca 13 rays 1.5-2 cm, the disk 1.5-2.5 cm wide. Glades and open woods; Cumberland Plateau region of Ky., Tenn., Ala., and Ga. July-Oct. The Ky. plants, with broad, basally truncate-cordate lower lvs, glabrous invol, and not quite so long and shaggy pubescence on the stem (hairs 2-3 mm), have been described as S. wasiotensis Medley and may be distinct.

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

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