The Collaborative International Dictionary of English v.0.48:

Chelone \Che*lo"ne\, n. [Gr. chelw`nh a tortoise. So named from
   shape of the upper lip of the corolla.] (Bot.)
   A genus of hardy perennial flowering plants, of the order
   Scrophulariace[ae], natives of North America; -- called
   also snakehead, turtlehead, shellflower, etc.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Chelone
    n 1: herbaceous perennials: shellflower [syn: Chelone, genus
         Chelone]