Grass Tree , one of the English names given to plants of the genus xanthorrhoea, which are also called grass-gum trees and black-boys. They belong to the order liliaceoe, and are especially distinguished by their crowns of long, pendulous, grass-like leaves, from the centre of which arises a long stem bearing at its summit a dense flower spike looking somewhat like a large cat-tail (typha). Some species have very short stems, while others have trunks 6 to 18 ft. high, which, with their singular tufts of leaves, form a striking feature in the Australian landscape. X. arborea, X. australis, both arborescent, and X. hastilis, nearly stemless, are the best known species, as they are the principal ones in cultivation as ornamental greenhouse plants. Two resins obtained from these plants have been known for some time; one is yellow and called Botany Bay resin and gum acaroides, and the other red, resembling dragon's blood, and known as black-boy gum. They are aromatic, contain cinnamic and benzoic acids, and have the general properties of the balsams proper.

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