Erigeron

Its English name, fleabane, is shared with related plants in several other genera. It appears to be derived from a belief that the dried plants repelled fleas^[10] or that the plants were poisonous to fleas.^[11] Botanist Thomas Meehan, though, calls "fleabane" a misnomer for North American species, rarely used in the United States "until it was employed in botanical works".^[12]

The generic name Erigeron is derived from the Ancient Greek words ἦρι (êri) "early in the morning" and γέρων (gérōn) "old man", a reference to the appearance of the white hairs of the fruit soon after flowering^[13] or possibly alluding to the early appearance of the seed heads.^[14] The noun γέρων is masculine,^[15] so that specific epithets should have masculine endings (e.g. glaucus) to agree with it. However, authors have incorrectly used neuter endings (e.g. glaucum), because the ending -on resembles the ending of Ancient Greek neuter second declension nouns, as Augustin Pyramus de Candolle did in his 1836 account of the genus.^[16]

The species may be annuals, biennials, or perennials. They are well-branched with erect stems, characterized by their numerous white, lavender, or pink ray flowers and yellow disc flowers. Some members of this group have no ray flowers. The pappus (=modified calyx, forming a crown) is shorter than in Aster and consists of bristles. The ray florets are narrower than in Aster but are longer than the involucre (=whorled bracts).

Many species are used as ornamental plants, with numerous named cultivars such as 'Wayne Roderick', 'Charity', 'Foersters Liebling', and 'Dunkelste aller' ("The darkest of all" with semi-double, deep-violet flower heads).^[17][18]

Erigeron species are used as food plants by the larvae of some Lepidoptera species including Bucculatrix angustata, Coleophora squamosella (which feeds exclusively on E. acris), Schinia intermontana, Schinia obscurata (both of which also feed exclusively on Erigeron), Schinia sexata (which feeds exclusively on E. glabellus) and Schinia villosa. Above-ground biomass of Erigeron in montane meadows decreases with decreased water availability/increased temperatures.^[19]

As of 2020^[update] Royal Botanic Gardens, Kew's Plants of the World Online lists around 460 species of plants in the genus Erigeron.^[2] Selected species include:

The following names are not accepted as of 2020^[update] in Royal Botanic Gardens, Kew's Plants of the World Online database:^[2]

• Erigeron acer – blue fleabane
• Erigeron corymbosus – long-leaf fleabane
• Erigeron greenei – synonym of Erigeron angustatus
• Erigeron hultenii – Hulten's fleabane