The Collaborative International Dictionary of English v.0.48:

Flax-plant \Flax"-plant`\, n. (Bot.)
   A plant in new Zealand (Phormium tenax), allied to the
   lilies and aloes. The leaves are two inches wide and several
   feet long, and furnish a fiber which is used for making
   ropes, mats, and coarse cloth.
   [1913 Webster]