Erigeron corymbosus Nutt.

Perennials, 10–50 cm; taprooted, caudices usually with relatively slender and short, often woody branches. Stems ascending (often purplish proximally), hirsutulous (hairs spreading-deflexed), eglandular. Leaves basal (usually persistent) and cauline; basal blades linear-oblanceolate, (30–)60–160 × 3–8(–14) mm, cauline 3-nerved, gradually or little reduced distally (bases attenuate), margins entire (apices acute), faces hirsutulous, eglandular. Heads 1–10(–16) in loosely corymbiform arrays (on branches from distal ¹ / 2 of stems, often well beyond middle). Involucres 5–7 × 7–13 mm. Phyllaries in 2–3 series, flat, densely hirsute to hirsuto-villous, sometimes sparsely minutely glandular. Ray florets 35–65; corollas blue or less commonly pink, 7–13 mm, laminae coiling at apices. Disc corollas 4–5.3 mm. Cypselae 2–2.5 mm, 2-nerved, faces sparsely strigose; pappi: outer of setae, inner of 20–30 bristles. 2n = 18.

Erigeron corymbosus is a North American species of flowering plants in the family Asteraceae known by the common name long-leaf fleabane. It is found in western Canada (British Columbia) and the western United States (Washington, Oregon, Idaho, Montana, Wyoming, Utah).

Erigeron corymbosus is a perennial herb up to 50 cm (20 inches) tall, forming a taproot. Each branch produces an array of up to 16 flower heads, each head with 35–65 blue or pink ray florets plus numerous yellow disc florets.