Compilation
Symphyotrichum expansum

Plants (10–)70–150 cm. Stems usually simple, often with short, leafy branches proximally. Heads 20–100, in open, diffuse arrays, primary branches longer than peduncles. Involucres 5–6.2 mm. Phyllaries 30–42, sub-ulate to lanceolate, narrow, green zones narrowly lanceolate. Ray florets (23–)27–37(–42) in (1–)2 series; laminae usually white, sometimes pink, 1.9–3 × 0.2–0.5 mm, longer than pappi, drying in 1–2 coils (apices shallowly to deeply lobed). Disc florets (6–)8–15; corollas 3.4–4.4(–4.7) mm. Cypselae 1.5–2.7 mm; pappi 3.5–3.8(–4.2) mm. 2n = 10.