The Collaborative International Dictionary of English v.0.48:

Crown-imperial \Crown"-im*pe"ri*al\ (-?m-p?"r?-al), n. (Bot.)
   A spring-blooming plant (Fritillaria imperialis) of the
   Lily family, having at the top of the stalk a cluster of
   pendent bell-shaped flowers surmounted with a tuft of green
   leaves.
   [1913 Webster]