fireweed

from WordNet (r) 3.0 (2006)

fireweed
    n 1: tall North American perennial with creeping rootstocks and
         narrow leaves and spikes of pinkish-purple flowers
         occurring in great abundance in burned-over areas or recent
         clearings; an important honey plant [syn: {fireweed},
         {giant willowherb}, {rosebay willowherb}, {wickup},
         {Epilobium angustifolium}]
    2: an American weedy plant with small white or greenish flowers
       [syn: {fireweed}, {Erechtites hieracifolia}]

from The Collaborative International Dictionary of English v.0.48

Fireweed \Fire"weed`\, n. (Bot.)
   (a) An American plant ({Erechthites hiercifolia}), very
       troublesome in spots where brushwood has been burned.
   (b) The great willow-herb ({Epilobium spicatum}).
       [1913 Webster]