The Collaborative International Dictionary of English v.0.48:

Pipsissewa \Pip*sis"se*wa\, n. [From American Indian.] (Bot.)
   A low evergreen plant (Chimaphila umbellata), with narrow,
   wedge-lanceolate leaves, and an umbel of pretty nodding
   fragrant blossoms. It has been used in nephritic diseases.
   Called also prince's pine.
   [1913 Webster]

WordNet (r) 3.0 (2006):

pipsissewa
    n 1: any of several plants of the genus Chimaphila [syn:
         pipsissewa, prince's pine]