An Australian plant of the genus Xanthorrhoea, 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.