Brachychiton is a genus of 30 or more species, most of which occur in tropical parts of Australia in dry areas or in rainforest. They are large shrubs or trees. One of the most commonly cultivated is the Illawarra flame tree (Brachychiton acerifolius) which is popular due to its spectacular crimson flowers. The Kurrajong (B.populneus) is one of the most widely distributed and is also a common tree in cultivation.
The bottle tree is a small to medium sized tree which may reach 18-20 metres in height although it is usually much smaller in cultivation in cooler areas. It has a characteristic bulbous trunk which gives rise to the common name and which makes the tree unmistakable. Leaves are about 100 mm long and may have entire margins or be deeply lobed. The cream, bell-shaped flowers occur in clusters at the ends of the branches in spring, but are not especially conspicuous. The flowers are followed by seed capsules which contain many large seeds.
B.rupestris is commonly cultivated and is hardy in a range of climates although it may be slow growing. The bottle shaped trunk may start to be noticeable at around 5-8 years of age. It tolerates a range of soils.
Propagation from seed is relatively easy without any pretreatment. The seeds are surrounded in the capsule by irritant hairs and are best collected using gloves.
Photo: Brian Walters