Xanthorrhoea (/zænθoʊˈriːə/) is a genus of about 30 species of flowering plants endemic to Australia and a member of family Xanthorrhoeaceae, being the only member of subfamily Xanthorrhoeoideae. The Xanthorrhoeaceae are monocots, part of order Asparagales.

Names

A reference to its yellow resin,Xanthorrhoea literally means "yellow flow" in Ancient Greek. Smith named it in 1798, from xanthos (‘yellow, golden’) and rhœa (‘flowing, flow’). The invalid Acoroides (‘Acorus-like’) was a temporary designation in Solander's manuscript from his voyage with Cook, originally not meant for publication.

The best-known common name for the Xanthorrhoea is blackboy, based on the purported similarity in appearance of the trunked species to an Aboriginal boy holding an upright spear. Some people now consider this name to be offensive, or at least belonging to the past, preferring instead grasstree and – for its resin-yielding species – grass gum-tree.

In the South West, the Noongar name balga is used for X. preissii. In South Australia, Xanthorrhoea is commonly known as yakka, also spelled yacca and yacka, a name probably from a South Australian Aboriginal language, mostly likely Kaurna.