Erigeron allocotus is a species of flowering plant in the family Asteraceae known by the common name Bighorn fleabane. It has been found only in the Bighorn Mountains of north-central Wyoming and southern Montana.

Erigeron allocotus is a short, branching shrub rarely more than 18 cm (7 inches) tall. Leaves are 3-lobed. The inflorescence generally consists of 2 or 3 flower heads per stem, each head with sometimes as many as 40 small yellow disc florets and surrounded by a ring of up to 40 white or blue ray florets.

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