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The Grass Tree: Its Uses and Abuses
Grass trees 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 arenaria, Xanthorrhoea nana and Xanthorrhoea minor, with the first species being most widely represented in the woodland communities.
Few populations remain due to degradation
|A hillside of grasstrees
Photo: Alfred Guhl
For nearly two centuries, land managers have showed 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.
||Developing fruits on a Xanthorrhoea sp.
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 share many attributes.
They are very slow growing, with some elderly specimens being amongst the oldest living plants on a worldwide scale, 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 tcapsules containing a few hard black seeds. Their excellent horticultural 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 the young grow at a rate of only a centimetre or so a year.
Transplanting from the bush is not recommended, unless imminent development will destroy the plant. Transplanting requires diligence and heavy equipment to extract the very deep underground stems and roots, whilst keeping the residual soil attached. Flooding the root zone helps maintain an intact root system and digging the new sites hole prior to the arrival, followed by deep watering of the plant's roots zone, aids the chances of survival.
|The original 'super glue'
Although not specifically a plant for fibre it was 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 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 wanned, but sets hard when cold. It had a number of uses including;
The versatility of this resin in the every day lives of the aborigines, made it a valuable trading item and was traded amongst tribes for other important collectables.
- Forming glue by mixing it with charcoal, beeswax or fine sand and dust.
- Gluing the cement stone heads to wooden handles and spears to shafts and tips.
- Waterproofing bark canoes and water carrying vessels.
A traditional Aboriginal favourite
Grass trees were a 'staple' plant for the aborigines, providing food, drink, fibre and materials for making implements and weapons.
Food and drink
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 the observing the dead leaves in the centre of the grass tree 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. A citric flavoured alcoholic brew could be made from fermenting the nectar over 3 to 5 days. An extra tang was added to the brew by crushing a few 'formic' ants into the beverage.
Early colonial use
The resin was important for colonists, beginning with its regular use in the early settlers dwellings, but declining in importance as plastics and acrylics superceded it, towards the middle part of the twentieth century. These uses included;
- Burned resin produced a pleasant scent which was common in early churches.
- The resin was the basis for a low cost spirit to manufacture varnishes, used on furniture and floors in settlers' houses.
- A stove polish and a metal coating for tins, used in meat canning and on brass instruments, were formulated from the resin.
- The resin was used for sizing paper, in soap making, perfumery and in manufacturing early gramophone
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.
From the newsletter of ASGAP's Wildlife and Native Plants Study Group, Summer 2001-02
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Australian Plants online - March 2004
Association of Societies for Growing Australian Plants