From The Collaborative International Dictionary of English v.0.48 :
Snowdrop \Snow"drop`\, n. (Bot.)
A bulbous plant ({Galanthus nivalis) bearing white flowers,
which often appear while the snow is on the ground. It is
cultivated in gardens for its beauty.
[1913 Webster]
Snowdrop tree. See Silver-bell tree, under Silver, a.
[1913 Webster]
From WordNet (r) 3.0 (2006) :
snowdrop
n 1: common anemone of eastern North America with solitary pink-
tinged white flowers [syn: wood anemone, snowdrop,
Anemone quinquefolia]