Solidago caesia L.

Solidago caesia is sometimes defined more broadly to include the erect-stemmed S. curtisii and S. ouachitensis.

Plants (20–)35–80(–100) cm; rhizomes woody, caudexlike. Stems 1–10+, usually blue to purple, glaucous, arching, straight , usually simple, occasionally with 2–3(–4) elongated lateral branches, glabrous or slightly strigose in arrays. Leaves: basal withering by flowering; proximal to mid cauline sessile, blades lanceolate, (47–)70–100(–150) × 8–20(–30) mm, margins serrate (with 0–24 teeth per side), apices acuminate, faces abaxially glabrous or sparsely hairy, adaxially sparsely hairy; distal sessile, blades narrowly lanceolate, (20–)40–70(–100) × (3.4–)5.6–11(–17) mm, margins entire to slightly serrate, faces glabrous or sparsely hairy. Heads 9–380, in short, secund, axillary and terminal racemo-paniculiform clusters (4.4–)13–36(–58) cm. Peduncles 2–10 mm, sparsely to moderately strigose; bracteoles linear, 1–8. Involucres narrowly campanulate, (3.5–)4.8–6(–7.2) mm. Phyllaries in ca. 3 series, unequal, outermost lanceolate (1–1.7 mm), acute, innermost linear-oblong (2.3–4 mm), 1-nerved, obtuse to acute. Ray florets 1–6; laminae (1.5–)2–3(–4) × ca. 1 mm. Disc florets 3–6(–9); corollas 2–3(–4) mm, lobes (0.5–)1–1.5(–2) mm. Cypselae 1–2(–2.5) mm, moderately to densely strigose; pappi 2–3(–3.7) mm.

Aster caesius (Linnaeus) Kuntze