WordNet (r) 3.0 (2006):

giant willowherb
    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]