72. Solidago rigida Linnaeus, Sp. Pl. 2: 880. 1753.
Aster rigidus (Linnaeus) Kuntze; Oligoneuron rigidum (Linnaeus) Small
Plants 30–150 cm ; caudices branching, woody. Stems 1–10+, erect, stout, hairy. Leaves: basal and proximal cauline usually present at flowering, abruptly narrowed to long petioles, blades ovate to rhombic, 80–200 × 24–50 mm, firm, flat, margins entire to crenate, sometimes undulate, apices obtuse to acute, faces densely hairy; mid to distal cauline sessile, blades ovate, 30–50 × 15–17 mm, stiff, greatly reduced distally, margins entire or finely serrate, sometimes undulate, apices acute to obtuse. Heads 9–190, in corymbiform arrays, compact or branches long and spreading, densely hairy throughout. Peduncles 3–15 mm, strigillose-canescent, bracteoles 1–3, linear-lanceolate. Involucres campanulate, 6–8 mm. Phyllaries in 3–4 series, unequal, oblong, conspicuously striate (3–5 pronounced nerves), obtuse. Ray florets 6–13; laminae 1.4–5.4 × 1.2–1.9 mm. Disc florets 14–35; corollas 4.3–6.1 mm, lobes 0.6–1.1 mm. Cypselae (obconic) 0.8–1.7 mm (ribbed), glabrous or strigillose apically; pappi 3–4 mm.
Subspecies 3 (3 in the flora): North America.
Solidago rigida is divided into three subspecies with distinct morphologies and partially overlapping ranges. Intermediates occur between the subspecies in areas of sympatry.