Plants 25-150 cm; rhizomes short to long creeping, forming few- to many-stemmed clones. Stems 1-20+, erect, proximally sparsely to moderately strigoso-villous, distally usually moderately to densely so. Leaves: basal 0; proximal cauline sessile, blades narrowly to broadly oblanceolate, 35-75(-100) × (6-)7.5-14(-20) mm, proximal much smaller, tapering to bases, margins subentire or finely serrulate to coarsely, sharply serrate (teeth 0-9 per side), ciliate, 3-nerved, sometimes obscurely so, apices acute, abaxial faces glabrate to sparsely short-strigose, adaxial glabrous; mid to distal cauline sessile, blades oblanceolate, becoming lanceolate distally, 20-60 × 4-8(-11) mm, largest near mid stem, somewhat to much reduced distally, margins entire or finely serrulate, rarely serrate (teeth 1-8 per side), usually becoming entire to sparsely serrulate distally, ciliate, apices acute, faces glabrous or sparsely strigoso-villous, more so along abaxial nerves. Heads 12-500+, sometimes secund, in short to long, thyrsiform or narrowly secund-pyramidal paniculiform arrays, usually congested, club-shaped to rarely wand-shaped, (2.5-) 10-20 × (2-)4-8(-10) cm, branches usually ascending or sometimes arching spreading. Peduncles 2-7 mm, sparsely to moderately short strigoso-villous; bracteoles 1-3 , linear, rarely minutely stipitate-glandular. Involucres narrowly campanulate, 2.5-3.5(-4) mm. Phyllaries in 3-4 series, strongly unequal, margins sparsely long ciliate, acute, faces glabrous, rarely sparsely minutely stipitate-glandular; outer lanceolate, inner linear-lanceolate. Ray florets (8-)11-15(-17); laminae 1-2.5 × 0.1-0.4(-0.7) mm. Disc florets (3-)5-11(-16); corollas 2.6-3.7(-4) mm, lobes 0.5-1.2 mm. Cypselae (narrowly obconic) 1-1.5 mm, sparsely to moderately strigose; pappi 2.5-3.3 mm. 2n = 18, 36. Flowering Aug-Oct. Sandy, gravelly soils, coastal headlands, thickets, open woods, meadows, along streams and creeks; 0-2800 m; Calif., Oreg., Wash.; Mexico (Baja California). In California, coastal plants of Solidago elongata often have thicker leaves; those of the Sierras are often membranous and obscurely triple-nerved. This species can be similar to S. lepida, which usually has much larger distal cauline leaves.
