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):

shellflower
    n 1: showy perennial of marshlands of eastern and central North
         America having waxy lanceolate leaves and flower with lower
         part creamy white and upper parts pale pink to deep purple
         [syn: shellflower, shell-flower, turtlehead,
         snakehead, snake-head, Chelone glabra]
    2: cultivated for its shining oblong leaves and arching clusters
       of white flowers with pink shading and crinkled yellow lips
       with variegated magenta stripes [syn: shellflower, shall-
       flower, shell ginger, Alpinia Zerumbet, Alpinia
       speciosa, Languas speciosa]