Growth Rate and Tree Rings

• The growth rate of the mulga is entirely dependent on the amount of water the tree receives. When rainfall is ample, the tree can grow fairly quickly and can gain up to more than three feet in height in a single year. During periods of drought, growth stops completely. This allows the tree to route what water and nutrients is does have toward vital life processes rather than grow, making it well equipped to weather through long periods of drought. When a tree is cut down the growth rings usually indicate how much the tree has grown during each year of it's life, but because the mulga can stop its growth entirely it can go years without new rings developing.
  
  

Branch Patterns and Leaves

• The branches of the mulga tree reach upwards, and are positioned so that they can channel any rainfall in toward their roots. The leaves of the tree are long and thin, allowing rainwater to run down them to the branches instead of running off them to the ground as with large, flat leaves. Because the leaves are so thin, there is also less evaporation off them. This rain capture system allows the tree to make the most of what rainfall it is exposed to, and together with its root system gives the tree an efficient system for collecting water.
  
  

Root Systems

• The mulga tree has a central tap root that can reach up to 7 feet into the ground. This tap root absorbs much of the water that the branches direct into the tree's core. The tree also has a complex system of other roots that reach well beyond the limits of the tree branches. By the time a young mulga is 4 inches tall, it can have a root system that extends up to 10 feet from its base. This allows the tree to absorb rain water that falls to the ground outside of the tree's reach that would otherwise be wasted. The roots also contain bacteria that can break soil nutrients down to their base components, including nitrogen. This means that the tree can survive in the most nutrient-poor of soils.
  
  

Toxins

• The mulga tree has a number of medicinal uses, but when it comes to defending itself against animals searching for food in the barren desert landscape, the mulga has a defense system that helps it keep from becoming lunch. The leaves of the tree have an extremely high protein content. When they are ingested by animals, there is a chemical reaction in the animal's stomach that can kill if enough of the leaves are eaten. In order to be prepared for human consumption, the leaves, bark or tannin is usually prepared by boiling to break it down first.