Source : Webster's Revised Unabridged Dictionary (1913)

Pieplant \Pie"plant`\, n. (Bot.)
   A plant ({Rheum Rhaponticum}) the leafstalks of which are
   acid, and are used in making pies; the garden rhubarb.

Source : WordNet®

pieplant
     n : long pinkish sour leafstalks usually eaten cooked and
         sweetened [syn: {rhubarb}]