Our October talk was by our group member Rupert Wheeler, who shared his considerable research into the unusual plants native to the red centre in the Northern Territory in Australia.
This vast, sparsely populated area is so called due to the red sands which have formed as iron-rich rocks of former mountains have weathered away. The main urban centre is Alice Springs and there are striking geological and landscape features in the area. This includes Lake Amadeus which is the remnant of an inland ocean that has been slowly drying up over millions of years, leaving a series of small islands amongst the salt crust. Kata Tjutta, 36 domes including the largest, Mount Olga, was probably one massive mound 600 million years ago that has since eroded away. It is formed of conglomerate, a sedimentary rock consisting of cobbles and boulders of varying rock types including granite and basalt, cemented by a matrix of red sandstone.
With 10 inches of rain per year, plants in this area have evolved to survive fire and drought, extreme heat and in some cases frost too. Some plants benefit from the regeneration that occurs after a bush fire, such as the Bush Tomato which is most productive at one year old. A common feature of plants is that seeds are very hard and take a long time to germinate.
Rupert began his tour at the Standley Chasm, 18 metres deep and formed where a vertical seam of Dolomite has eroded away. Plants he observed here included the very rare Flannel Flower, a white daisy which clings to the rock face and has total population of 1000 plants.
A large number of plants in the area have a long tradition of use by local people. For example the Apple Bush, with apple-scented foliage, is used for the treatment of colds by placing up the nose or within a pillow. The Desert Rattlepod is a xerophyte with waterproof seeds that are toxic to livestock but they ooze a white liquid that people consume as a sweet treat. The bark is used as a twine and the leaves are medicinal.
The Desert Oak is takes an unusual form in its youth. These young plants grow a single stem and focus all their energies on growing a tap root, which can reach down 40 feet. It may be many years before the tree finds a sufficient, deep source of water to enable branching. The needle-like ‘leaves’ are in fact stems and what look like nodes are very small leaves. These leaves drop and form a ground cover that prevents other plants from growing and competing with the tree for nutrients and water.
We really enjoyed discovering the landscape and plants of this striking area and their use by the local people who have valued them for millennia. Many thanks to Rupert for sharing his knowledge and amazing photos with us.
