From The Collaborative International Dictionary of English v.0.48 :
Bugbane \Bug"bane`\, n. (Bot.)
A perennial white-flowered herb of the order
Ranunculace[ae] and genus Cimiciguga; bugwort. There are
several species.
[1913 Webster]
From WordNet (r) 3.0 (2006) :
bugbane
n 1: North American plant having large leaves and yellowish
green flowers growing in racemes; yields a toxic alkaloid
used medicinally [syn: white hellebore, American
hellebore, Indian poke, bugbane, Veratrum viride]
2: a plant of the genus Cimicifuga having flowers in long
racemes or panicles reported to be distasteful to insects