The (Kurrajong) Brachychiton populneus is an under utilised Australian native species that has high drought tolerance coupled with an attractive broad-form that provides good shade coverage. The Kurrajong definitely has a role to play in contemporary urban landscapes.
Victoria, New South Wales, Queensland, Northern Territory
Modest size evergreen, broad domed tree of 12 to 15m in height by 12 to 15 m in crown diameter generally with a stout trunk.
Bark is green and smooth on young trees and smaller branches in upper crown, becoming dark, compacted and coarsely fissures on stout trunk to larger branches of maturing specimens.
Foliage discolourous, glossy green above and paler green below. Mostly entire but sometimes with up to 3 small pointed lobes depending on subspecies. Subspecies populneus has mostly entire leaves reminiscent of Poplar (Populus genus) and subspecies trilobus has 3, sometimes 5, narrow lobes and more northerly and inland distribution.
Flowers, appearing in October to December, are cream to pale green bell shaped flowers with pale pink to purple flecks in the throat of the bell.
Fruit are a leathery boat shaped follicle with hairs on the seeds held within.
Drought tolerant, prefers free draining soils. Low tolerance of waterlogged sites and excessive root disturbance. Can be transplanted successfully as a smaller tree (3-4m) but presence of residual tap root can be problematic.
Based on a mature size specimen of Kurrajong (12m crown spread) would require approximately 113m2 area or 68m3 root volume (crown projection method).
Readily available and as advanced specimens of 2-4m stock with generally successful establishment in free draining soils and sunny position. Slow to moderate growth rate.
Uses & management
The tree has been observed to be thriving in the recent drought conditions throughout south-eastern Australia even in comparison to other species recognised as drought tolerant such as many eucalypt species and exotic conifers and evergreens.
It is a terrific dense, broad domed tree offering cool shade suitable for use in average to larger gardens. An ideal street tree and suitable for pruning below electrical services.
Wood properties are low density and fibrous and shows a relatively poor ability to compartmentalise decay. Kurrajong has a generally reliable structure so therefore has a low susceptibility to decay unless wounded by external causes. Avoid trees with included bark forks although even these are rarely seen to have failed.
Foliage can be used as a supplementary source of fodder in conjunction with other types.
Has the potential to self-propagate on disturbed and neglected sites but otherwise has a relatively low weed potential.