fleabane

from WordNet (r) 3.0 (2006)

fleabane
    n 1: hairy perennial Eurasian herb with yellow daisylike flowers
         reputed to destroy or drive away fleas [syn: {fleabane},
         {feabane mullet}, {Pulicaria dysenterica}]
    2: any of several North American plants of the genus Erigeron
       having daisylike flowers; formerly believed to repel fleas
    3: common North American weed with linear leaves and small
       discoid heads of yellowish flowers; widely naturalized
       throughout temperate regions; sometimes placed in genus
       Erigeron [syn: {horseweed}, {Canadian fleabane}, {fleabane},
       {Conyza canadensis}, {Erigeron canadensis}]

from The Collaborative International Dictionary of English v.0.48

Fleabane \Flea"bane`\, n. (Bot.)
   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}.
   [1913 Webster]