Xanthorrhoea (/zænθoʊˈriːə/) is a group (genus) of about 30 types (species) of plants that store water and have flowers. They belong to the Asphodelaceae family. These plants only grow in Australia. People call them by many names like grasstree, grass gum-tree (for those that produce resin), kangaroo tail, balga (in Western Australia), yakka (in South Australia), yamina (in Tasmania, from the palawa kani language), and black boy (or "blackboy"). The most common type is Xanthorrhoea australis, and some of these names are used just for this species.
Description
The dead "trunk" of Xanthorrhoea is a hollow ring made from old leaf bases. The plant moves nutrients through bundles in the center. The soft tissue inside breaks down over time.
All Xanthorrhoea plants live for many years and have a special growing part in their stem. Many types grow a stem above the ground, but some do not. The stem can take up to 20 years to appear. The plant starts as a bunch of stiff, grass-like leaves, and the main stem grows slowly underneath. The trunk is rough because it is made from old leaf bases around the thickened stem. Some plants have one stem, some grow branches if the main growing point is hurt, and others naturally have many branches.
The flowers grow on a long spike above a bare part called a scape. This spike can be over 3–4m (9.8–13.1ft) long in some types. The plants flower at certain times, which can be different for each type, and often after a bushfire. Fires burn the leaves and blacken the trunk, but the plant survives because the dead leaves around the stem protect it from the heat.
Xanthorrhoea plants grow slowly. Some grow between 0.8–6cm (0.31–2.36in) each year. They grow faster when the weather and rain are good. After they are established, the growth speed varies a lot between types. For example, a five-metre-tall (16ft) tall Xanthorrhoea that grows fast might be 200 years old, but a slower-growing one of the same height could be 600 years old.
The name Xanthorrhoea means "yellow flow" in Ancient Greek, named for its yellow resin. It was named in 1798 by James Edward Smith. Some other Australian plants look similar, but are not related, and have sometimes been confused with Xanthorrhoea.
Names
People call Xanthorrhoea by many names like grasstree, grass gum-tree, and kangaroo tail. The name grasstree is also used for other plants. In Western Australia, it is called balga, a word from the Noongar language. The name "black boy" was used for many years because the blackened trunk after fire looks like a dark figure, but this name is now seen as offensive. In Tasmania, the plant is called yamina by Aboriginal people. In South Australia, it is called yakka or yacca, likely from the Kaurna language. The Ngarrindjeri people call it Bukkup.
Xanthorrhoea plants only grow in Australia. They are found in all states and territories. Some types grow only in small areas, while others are found in many places.
Grasstrees grow in coastal heaths and wet or dry forests in Australia. They can survive drought and frost. They usually grow in very well-drained, poor soil. They have shallow roots that get nutrients from decaying leaves and store food in their stems.
These plants have special features to survive fires. The thick dead leaves around the stem protect the plant from heat. Fire clears dead leaves and helps the plants flower. After fire, the soil is richer with ash, which helps the plant grow. These slow growing plants were among the world's first flowering plants.
Xanthorrhoea also has a helpful relationship with fungi in its roots. The fungi help the plant get water and nutrients, especially in poor soil. However, the plant can get sick from a disease called phytophthora dieback, which harms its roots and can kill it.
Growing Xanthorrhoea
You can grow Xanthorrhoea from seeds, which are easy to collect and start. They grow slowly but can reach about 10cm (3.9in) tall with leaves up to 1.5m (4ft 11in) in 10 years. It can take 30 years to grow a big trunk. Most plants sold in nurseries are taken from the wild and are expensive. Many nursery plants die because they get too much water. The best way to move these plants is with a lot of soil around their roots.
Xanthorrhoea is very important to the Indigenous Australian people. They use it in many ways. The flower spike can be used as a light handle for spears. It is also soaked in water and the nectar from the flowers gives a sweet-tasting drink.[source?] The flowers can be soaked in water to make a sweet drink. The flowers can also show direction because flowers on the sunny side open first.
The resin from the plant is used to make spears. and as glue for fixing things like water containers and didgeridoos. The dried flower stalk can be used to make fire by rubbing it with another stick. In Tasmania, Aboriginal people use the leaves for weaving.
In the past, resin from Xanthorrhoea was used in Australia for:
↑Campbell, Colin (25 February 2006). "Grass Tree". Gardening Australia. Australian Broadcasting Corporation. Retrieved 14 August 2018.
↑Hopper, S.; Lambers, H. (2014), "9. Human relationships with and use of Kwongan plants and lands", Plant life on the sandplains in southwest Australia: a global biodiversity hotspot: kwongan matters, Crawley, Western Australia UWA Publishing, pp.287–90, ISBN978-1-74258-564-2
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