|Xanthorrhoea australis (xanthorrhoeaceae)
A plant with a large rounded crown of long linear leaves on a trunk which can be up to two metres tall. When present the trunk is usually blackened by fires which promote flowering which may be in the form of a spectacular display with hundreds of the tall flower spikes present together. These spikes are packed with flowers which attract a large variety of nectar loving insects and birds. White stamens are a prominent feature of the flowers.
Photo: Launceston Field Naturalist Club
Grass trees or blackboys are very much part of the Australian landscape and uniquely Australian. They fascinated the first European settlers, since they were unlike any other known plant. In fact, they are a living fossil developed early in the evolutionary stakes for flowering plants.
Lumbered with a difficult to pronounce and even more difficult to spell botanical name of Xanthorrhoea, they have recently become prized for their landscape attributes. Tasmania has four species namely Xanthorrhoea australis, Xanthorrhoea areanaria, Xanthorrhoea nana and Xanthorrhoea minor (syn. bracteata), with the first species being most widely represented in the woodland communities.
Few Populations Remain due to Degradation
For nearly two centuries, land managers have shown both apathy and lack of concern towards these very slow growing plants and their associated sandy, well-drained habitats. Today, the communities containing these grass trees are very limited in extent, with many of the remnants subjected to various degradation processes. These are taking their irretrievable toll on the grass tree population, which include land clearing, land improvements and the spread of the phytophthora fungal disease.
A sad story of destruction
This relates to an experience with an exploitative landowner in an outer-suburban area well known for its grass trees, who offered for sale large numbers of magnificent specimens. His aim was to cash in on the grass trees, prior to decimating their woodland community, in order to improve the land for a few sheep.
Although information on the rarity of his resource was sensitively provided, the outcome was the clearing of many acres of this grass tree community and the sale of transplanted specimens to unsuspecting nurseries. The word ‘unsuspecting’ is used because, unless expertly transplanted, they tend to die slowly, leaving the nursery out of pocket, along with many angry customers demanding refunds.
Sadly, even today the remaining grass tree’s survival continues to be threatened, whilst the property remains out of sight from the road and in the possession of the farming family
Features which inspire landscapers and backyard gardeners alike.
Grass trees are related to the lilies, but are placed in a separate family. They are close relatives with the sagg (Lomandra longifolia) with which it shares many attributes. They are very slow growing, with some elderly specimens being amongst the oldest living plants in the world, surviving for many hundreds of years.
Beautiful old examples are survivors of many wild fires and develop into architectural masterpieces. Wild fire can cause their blackened trunk (1 to 2 metres) to branch into two or even more heads. These consist of thick, rough corky bark, surrounded by a whorl of long, wiry leaves with unique flowers.The flowers appear as long cylindrical spikes (1 to 3 metres) arising out of the skirt of grass like leaves, often flowering as a direct response to a very recent wild fire. This ability to be one of the first flowers to appear after a wild fire ensures a food source for many insects and birds, in an otherwise alien, blackened moonscape environment. The tops of these spikes are covered with a dense pattern of tiny white to yellow florets. These in turn produce seed capsules containing a few hard black seeds. Their excellent textural qualities make grass trees prized garden exhibits.
Cultivation is not easy
Cultivation presents great challenges, with the
seed taking up to a year to germinate and young plants growing at a rate
of only a centimetre or so a year.
A Traditional Aboriginal Favourite
Grass trees were a ‘staple’ plant for the aborigines, providing food, drink, fibre and materials for making implements and weapons.
As a food source, the white, tender sections of leaf bases, the growing points of stem and succulent roots were all eaten regularly. The removal of the growing point was rare as it destroyed the plant altogether. The seeds were collected and ground into a flour to provide dough for cooking a type of damper, within the ashes of a wattle wood fire. They frequently dug out edible grubs found at the base of the trunk. The grub’s presence could be detected by observing the dead leaves in the centre of the crown. Small sweet pockets of honey could also be extracted from the carpenter bee’s cellular nests, which were often bored in the soft pith of the flower stalk.
To wash this down, the nectar from the flower could be extracted by soaking it in water filled bark troughs, to produce a thick sweet drink. Fermenting the nectar over 3 to 5 days could make a citric flavoured alcoholic brew. An extra tang was added to the brew by crushing a few ‘formic’ ants into the beverage.
The Original Super GlueAlthough not specifically a plant for fibre it wa s very useful in crafting of aboriginal tools. The light straight flower stalk served as a butt-piece for spears. A tip section of tea tree would then be attached to the end of the spear and hardened in the fire before being used for hunting.
Mainland aboriginals used pieces of very dry flower stalk for making fire with a drilling stick.
The leaves produce a hard waterproof resin, which
could be collected from the base of the trunk. This resin melts when warmed,
but sets hard when cold. It had a number of uses including;
The versatility of this resin in the everyday lives of the aborigines, made it a valuable item which was traded amongst tribes for other important collectables.
Early Colonial Use
The resin was important for colonists, beginning
with its regular use in the early settlers dwellings, but has declined
in importance as plastics and acrylics superseded it, towards the middle
of the twentieth century. These uses included:
Although the grass tree has been of immense value to the aborigines and colonists, its future lies in the hands of the landowners and nature reserve managers, who are blessed with the woodland remnants which support the remaining populations.
It is a true icon of the Aussie bush and as such, provides a unique identity to our Australian landscape.