Plants 40-120 cm; caudices branching, woody. Stems usually 1, erect, glabrous, sparsely hairy in arrays. Leaves: basal when present similar to proximal cauline; proximal cauline often withering by flowering, tapering (sometimes rather abruptly) to short, winged petioles, blades ovate-lanceolate, 60-100(-150) × 30-40(-50) mm, thin, margins coarsely serrate, apices acute, abaxial faces hirsute on main nerves, adaxial sparsely hirsute to somewhat scabrous; mid to distal cauline subsessile to sessile, blades lanceolate, 20-50 × 5-20 mm, gradually reduced distally, margins entire. Heads 20-150, secund, in open paniculiform arrays, proximal branches elongate and widely divergent, sometimes pyramidal-secund with proximal branches short and recurved-secund. Peduncles 1.7-2 mm, sparsely to moderately short hispido-strigose, bracteoles 2-7, ovate, grading into phyllaries. Involucres 3-4 mm. Phyllaries (16-18) in 2-3 series, unequal; outer ovate, acute, inner linear-lanceolate, obtuse to acute. Ray florets 3-6; laminae 1-2 × 0.5-1 mm. Disc florets 4-7; corollas 2.7-3 mm, lobes 0.5-1.1 mm. Cypselae 1-1.6 mm, finely hairy; pappi ± 2.5 mm. Solidago helleri is possibly a hybrid of S. ulmifolia with S. delicatula.
Stems 4-12 dm, glabrous or nearly so below the infl, mostly solitary or paired from a caudex or short rhizome; lvs numerous, thin, sharply serrate, loosely hirsute at least on the midrib and main veins beneath; basal lvs wanting or with well developed, elliptic to elliptic-obovate blade abruptly contracted to the petiole, but generally soon deciduous; lowermost cauline lvs tending to be soon deciduous and smaller than the persistent ones just above, which are ovate or rhombic-ovate to elliptic or lance-elliptic, acute or acuminate, broadly short-petiolate or tapering and subsessile, mostly 6-12 נ1.2-5.5 cm, the lvs thence ±reduced upward, those at the base of the infl generally small, relatively broad, and often numerous; infl paniculiform, with recurved- secund branches, these generally few, elongate, and divergent, the heads crowded; invol 2.5-4.5 mm; rays 3-5, minute; disk-fls 4-7; achenes short-hairy; 2n=18. Woods; N.S. to Ga. and Fla., w. to Minn., Kans., and Tex. Ours is var. ulmifolia.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.