FLEABANE
horseweed, Canadian fleabane, fleabane, Conyza canadensis, Erigeron canadensis
(noun) common North American weed with linear leaves and small discoid heads of yellowish flowers; widely naturalized throughout temperate regions; sometimes placed in genus Erigeron
fleabane
(noun) any of several North American plants of the genus Erigeron having daisylike flowers; formerly believed to repel fleas
fleabane, feabane mullet, Pulicaria dysenterica
(noun) hairy perennial Eurasian herb with yellow daisylike flowers reputed to destroy or drive away fleas
Source: WordNet® 3.1
Etymology
Noun
fleabane (plural fleabanes)
Any of various species of flowering plants, mostly in two subfamilies in Asteroideae, that typically repel insects
Astereae
Conyza (butterweeds or horseweed)
Erigeron, especially Erigeron acre (blue fleabane)
Inuleae
Inula (yellowheads)
Pluchea (camphorweeds)
Pulicaria (false fleabane), especially common fleabane (Pulicaria dysenterica subsp. dysenterica, formerly Inula dysenterica)
In Cichorioideae, Vernonia (ironweeds).
Source: Wiktionary
Flea"bane`, n. (Bot.)
Definition: One of various plants, supposed to have efficacy in driving
away fleas. They belong, for the most part, to the genera Conyza,
Erigeron, and Pulicaria.
Source: Webster’s Unabridged Dictionary 1913 Edition