from
The Collaborative International Dictionary of English v.0.48
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}).
[1913 Webster]