- Name also: Bitter Fleabane
- Latin synonym: Erigeron acer
- Family: Daisy Family – Compositae, subfamily Asteroideae
(formerly Aster Family – Asteraceae)
- Growing form: Annual or biennial, occasionally perennial herb.
- Height: 20–50 cm (8–20 in.). Stem erect, branchless until inflorescence, grooved, hairy–glabrous, often reddish brown (sometimes brownish or green).
- Flower: Single flower-like less-than-10 mm (0.4 in.) capitula surrounded by involucral bracts. Capitula’s ray-florets purple, brownish red or white, tongue-like; intermediate florets thread-like (sometimes lacking); disc florets yellow, tubular, small. Stamens 5. Pistil of 2 fused carpels. Involucral bracts overlapping, narrow, sharp-tipped, usually hairy, with glandular hairs, green–red. Capitula usually abundantly corymbose–in a racemose cluster.
- Leaves: In basal rosette and alternate on stem (sometimes rosette lacking). Rosette leaves and lowest stem leaves stalked, uppermost stalkless. Blade narrowly obovate–lanceolate, with entire margins–shallow-toothed, usually both sides straight-haired (sometimes virtually glabrous).
- Fruit: Hairy–virtually glabrous, yellowish brown, 1–2 mm (0.04–0.08 in.) long achene, tip with white–yellowish–reddish–brownish unbranched hairs.
- Habitat: Roadsides, meadows, dry meadows, meadows, old lawns, wasteland, gravel pits, rocky outcrops, river banks, hillsides, gravel shores.
- Flowering time: June–August.
- Endangerment: Ssp. decoloratus is vulnerable.
Genus Fleabane’s scientific name Erigeron comes from the Greek words eri, ’early’ and geros, ‘becoming grey’. Of the species that grow in Finland, ‘going grey while still young’ is a good way of describing blue fleabane at least, which grows very abundantly: its most common subspecies ssp. acris is actually greyish with dense hair from the moment it germinates. It is common and in some places abundant in the south of the country on rocky outcrops, dry meadows and banks.
Blue fleabane is very diverse, and there are even glabrous subspecies. Ssp. droebachiensis is noticeably sparsely haired and might even be glabrous. The northernmost of the species and perhaps the most different-looking is ssp. politus, which is quite common in Lapland. Its stem and leaves are also almost glabrous, but the most noticeable thing is perhaps the scarcity of its capitula. Ssp. brachycephalus grows furthest east and is a paler colour than the rest: the capitula’s ray-florets are white or light purple at most, its leaves are greenish or brownish and it lacks the reddish colour of the others. The inflorescence on vulnerable ssp. decoloratus is even paler, and it has even less capitula. It has a very small habitat, originates from Finland and is a species which only grows in the north-east of the country and behind the eastern border with Russia. A total of four different fleabane species grow in Finland, although the three others are rare Lapland fell plants. They usually only have solitary heads which terminate a branchless stem.