Solidago caesia is a perennial herb, 30 cm to 1 m tall, from a stout, woody base, sometimes sparsely colonial from creeping rhizomes, stems slender, waxy, pale blue-green or purplish.
Leaves alternate 6-12 cm long, 1-3 cm wide, narrow, pointed at both ends, margin toothed, stalk none (or small).
Flowers yellow, of two types, in small heads subtended by bracts, ray flowers 3-4, disk flowers 5-8, bracteate base of flower heads 0.3-0.4 cm tall; inflorescence of dense clusters of flower heads in leaf axils along top of stems, sometimes branching in large plants; insect pollinated (Abrahamson and Gadgil 1973); blooms Aug.-Oct.
Fruit dry, achenes, hairy, plumed, wind dispersed.
Wetland status: FACU.
Frequency in NYC: Occasional
Habitat: Undisturbed forest understory, shade tolerant. Tolerates acid soil down to pH 4.0. Often planted in forest understory restorations.