Erigeron acer is a widespread species of herbaceous flowering plant in the family Asteraceae. Common names include bitter fleabane and blue fleabane. The species is native to Canada, colder parts of the United States, northern, central, and southeastern Asia, and most of Europe.
Erigeron acer is a biennial or perennial herb up to 100 cm (40 inches) tall, producing a taproot and a woody rhizome. One plant can produce many small flower heads, each with pink, lilac, or occasionally white ray florets and yellow disc florets.
Subspecies and varieties: Erigeron acris subsp. acris Erigeron acris subsp. angulosus (Gaudin) Vacc. Erigeron acris subsp. arctophilus (Rech.f.) Rech.f. Erigeron acris subsp. asadbarensis (Vierh.) Rech.f. Erigeron acris subsp. botschantzevii Erigeron acris subsp. brachycephalus (H.Lindb.) Erigeron acris subsp. droebachensis (O.F.Müll.) Arcang. Erigeron acris subsp. kamtschaticus (DC.) Erigeron acris var. khasianus (Hook.f.) Erigeron acris subsp. lalehzaricus. Erigeron acris subsp. mesatlanticus (Maire) Maire Erigeron acris var. multicaulis (Wall. ex DC.) Erigeron acris subsp. phaeocephalus. Erigeron acris subsp. podolicus (Besser) Nyman Erigeron acris subsp. politu (Fr.) H.Lindb. Erigeron acris subsp. pycnotrichus (Vierh.) Grierson Erigeron acris subsp. staintonii.