Plants 30-90 cm; caudices, sometimes also creeping rhizomes as well. Stems usually 1-3, ascending to erect, scabrous to loosely puberulent. Leaves: basal and proximal usually withering by flowering, tapering to long-winged petioles, blades oblanceolate, 30-100 × 7-20(-30) mm, margins serrate or crenate, mid usually largest, apices acute to obtuse, acuminate, faces scabrous; mid and distal cauline subsessile (1 mm) or sessile, blades (sometimes ± shiny) elliptic to oblanceolate, 10-50 × 5-15(-25) mm, greatly reduced distally, grading into bracts, firm, bases convex-cuneate to rounded, margins finely serrate , often 3-nerved, nerves usually distinct abaxially, faces distinctly scabrous. Heads 20-260, in paniculiform arrays, narrowly to broadly secund, pyramidal, branches recurved, secund. Peduncles 0.5-2 mm; bracteoles 1-5, linear-lanceolate to ovate, minute, grading into phyllaries distally. Involucres narrowly campanulate, 3-5 mm. Phyllaries in 3-4 series, unequal, oblong, midnerves swollen distally, obtuse or acute to slightly acuminate. Ray florets 4-7; laminae 2-3.5 × 0.2-0.7 mm. Disc florets 4-6; corollas 3 mm, lobes 1 mm. Cypselae 1.5-2.5 mm, sparsely to moderately short-strigose; pappi 3 mm. 2n = 18, 36. Flowering Aug-Oct. Open rocky places, dry woods, especially calcareous soils; 0-600 m; Ark., Ga., Ill., Kans., Ky., La., Mo., N.C., Okla., S.C., Tex. Solidago radula is disjunct in Georgia, North Carolina, and South Carolina. J. R. Beaudry (1969) reported a diploid from Smithville, Dekalb County, Tennessee; that has not been confirmed.
Plants 4-12 dm from a caudex, at least sometimes with creeping rhizomes as well; stem scabrous to shortly and loosely hirsute; lvs chiefly cauline, numerous, firm, elliptic or lance-elliptic to rather narrowly elliptic-obovate, subsessile, obscurely to evidently toothed or the upper entire, ±evidently trinerved, subglabrous, or more commonly scabrous-hirsute (seldom more softly spreading-hairy), mostly 2-5 times as long as wide, the larger ones 3-8 נ1-3 cm; infl paniculiform, with densely fld, ±recurved-secund branches, or occasionally simple and nodding; invol glabrous, 3.5-5.5 mm, its bracts relatively broad and firm, acutish to more often obtuse or broadly rounded; rays 4-7,
2-3.5 mm; disk-fls 4-6; achenes short-hairy; 2n=18. Open, rocky places and dry woods, especially in calcareous soil; Mo. and s. Ill. and w. Ky. to Okla., La., and Tex.; N.C.; Ga.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.