WordNet sense 1 (hairy perennial Eurasian herb with yellow daisylike flowers reputed to destroy or drive away fleas):

feabane mullet, Pulicaria dysenterica

WordNet sense 2 (common North American weed with linear leaves and small discoid heads of yellowish flowers; widely naturalized throughout temperate regions; sometimes placed in genus Erigeron):

horseweed, Conyza canadensis, Canadian fleabane, Erigeron canadensis