Facts About the Grass Tree


There is perhaps no other single plant other than the gum tree (Eucalyptus) that lends the look of the Australian outback to a landscape than the grass tree (Xanthorrhoea spp.). From a distance it looks like a skinny stump with an ornate, grass-like head. Up close you notice its sharp leathery leaves and blackened stem from recent bushfires. Although hardiness depends on species, these subtropical plants grow best where frosts are rare or mild, such as in U.S. Department of Agriculture hardiness zones 9 through 12.


Grass trees comprise 66 species in the plant genus Xanthorrhoea, which is found only on the continent of Australia. They grow in coastal heathlands as well as wet and dry forests across the mainland and the island of Tasmania.


Aboriginals referred to these tree-like shrubs as "balga," a word translated into English as "black boy." Fire is a frequent aspect of the Australian bushlands and once the plant endured a wildfire, its foliage would be scorched away and its trunk-like stem blackened with soot. It is also called balga grass and the grass tree because of the thin leaves that resemble tufts of narrow grass blades emanating from the tip of the stem. The botanical name Xanthorrhoea comes from the Greek words meaning "yellow" and "discharge", referring to the gum exuded from the stem base.


Grass trees are evergreen shrubs that are tree-like in habit, described as arborescent. This slow-growing plant develops a thick trunk-like stem, with a tuft of linear, light olive-green leaves protruding from the tip. Depending on species, these grass-like leaves are short or long. Dead leaves persist and droop downward on the stem. Flowering occurs when a singular, narrow, upright spike towers up from the leaf cluster to bear hundreds of small, white flowers in an inflorescence. The seeds that later develop from a blossom reside in a dry capsule that splits open to propel the three to six seeds far from the mother plant. The core or endosperm of the seed is rich in oil.

Aboriginal Uses

Native Australians found a use for all parts of the grass tree according to the Australian National Botanical Garden. Nectar from the flowers was enjoyed as food or soaked in water as a sweet beverage while the dried flower stalk could be used as fire kindling or for making spear shafts. The stalk's soft base could be drilled by hand to start fire. The most tender young leaves' soft basal tissues were eaten while the tough, mature leaves acted like cutting utensils. Resin from the stump could be used as an adhesive. Moreover, the resin could be made into lacquers and varnishes and protected metal from rusting.

Growing Insights

Grass trees need a well-draining, sandy soil with occasional application of an organic manure or bone meal, according to Australian Plants Online. A sugary solution added annually to the root zone tends to promote beneficial mycorrhiza in the soil. Do not overwater the plants. They grow quite well from seed and should be planted where they are to permanently grow, since they resent root disturbance and transplant poorly. Within Australia, there are restrictions that limiting the harvest of plants or seeds as many grass tree species are endangered because of habitat loss from human development.

Keywords: Xanthorrhoea, Australian plants, Outback shrubs, black boy

About this Author

James Burghardt has written for "The Public Garden," "Docent Educator," nonprofit newsletters and for horticultural databases, becoming a full-time writer in 2008. He's gardened and worked professionally at public and private gardens in Colorado, Florida, Minnesota, New York, North Carolina and Pennsylvania. He has written articles for eHow and GardenGuides.