Source : Webster's Revised Unabridged Dictionary (1913)

Grass tree \Grass" tree"\ (Bot.)
   (a) An Australian plant of the genus {Xanthorrh[oe]a}, having
       a thick trunk crowned with a dense tuft of pendulous,
       grasslike leaves, from the center of which arises a long
       stem, bearing at its summit a dense flower spike looking
       somewhat like a large cat-tail. These plants are often
       called ``blackboys'' from the large trunks denuded and
       blackened by fire. They yield two kinds of fragrant
       resin, called {Botany-bay gum}, and {Gum Acaroides}.
   (b) A similar Australian plant ({Kingia australis}).

Source : WordNet®

grass tree
     n 1: elegant tree having either a single trunk or a branching
          trunk each with terminal clusters of long narrow leaves
          and large panicles of fragrant white, yellow or red
          flowers; New Zealand [syn: {cabbage tree}, {Cordyline
          australis}]
     2: any of several Australian evergreen perennials having short
        thick woody stems crowned by a tuft of grasslike foliage
        and yielding acaroid resins [syn: {Australian grass tree}]
     3: gaunt Tasmanian evergreen shrubby tree with slender tapering
        leaves 3 to 5 feet long [syn: {tree heath}, {Richea
        pandanifolia}]