The Collaborative International Dictionary of English v.0.48:

Pasque \Pasque\, n. [OF. pasque.]
   See Pasch.
   [1913 Webster]

   Pasque flower (Bot.), a name of several plants of the genus
      Anemone, section Pulsatilla. They are perennial herbs
      with rather large purplish blossoms, which appear in early
      spring, or about Easter, whence the common name. Called
      also campana.
      [1913 Webster]

WordNet (r) 3.0 (2006):

pasque flower
    n 1: any plant of the genus Pulsatilla; sometimes included in
         genus Anemone [syn: pasqueflower, pasque flower]