Brachychiton rupestris (2008)

By Eric Driskill (June 2008)

Brachychiton is a genus of 31 species of trees and large shrubs native to Australia with one species in New Guinea. Brachychitons were originally classified in the family Sterculiaceae, which is now within Malvaceae.

Many brachychitons are known as “kurrajong” or simply bottle trees. Kurrajong, an Aboriginal word for “fiber-yielding plant,” refers to the use of bark from many of these trees for weaving nets, ropes and baskets. The name Brachychiton is derived from the Greek “brachys,” short; and “chiton,” tunic; which refers to its loose seed coats.

Commonly known as the Queensland bottle tree, B. rupestris is native to eastern Australia in Queensland. It has a characteristic pachycaul trunk, which gives rise to the common name and which makes the tree recognizable. It can grow to over 40 feet in height, and its swollen bottle-shaped trunk is primarily used for water storage. Leaves on every tree are variable from narrow and elliptic to deeply divided.

All Brachychiton species are monoecious with separate male and female flowers on the same plant. The flowers have a bell-shaped perianth consisting of a single series of fused lobes, which is regarded as a calyx despite being brightly colored in most species.

The female flowers have five separate carpels that can each form a woody fruit containing several seeds. The flower color is often variable within species. B. rupestris has clusters of yellow flowers which are hidden in the foliage and are not especially conspicuous.

Plants are easily propagated from seed and grow best in well-draining, slightly acidic soil in full sunshine. The typical plant in habitat or grown in temperate subtropical and tropical climates will develop the unique bottle shape in about five to eight years. Some sources report this to take up to 15 years.

B. rupestris is commonly found in succulent collections in pots and sought for the trunk and roots, which over time can be raised to display a twisting mass of roots which are a work of art with no two alike. Like so many other succulents grown for the hidden treasures which develop under the soil to be raised one day, the Queensland bottle tree is a plant that adapts well to many climates.

I started collecting plants when I was in high school. Growing up in Oklahoma, it wasn’t odd that I started with various opuntias and Echinocereus reichenbachii, since they were readily available on most hillsides in southern Oklahoma. I quickly added to my small collection with any oddity I could find. One of the first succulents I purchased was a B. rupestris.

I have to admit that at the time I didn’t know it was a succulent. In fact I didn’t know those first plants would eventually turn into a hobby I would enjoy for so many years to come.

Not really knowing much about plants, I assumed I had somehow killed my bottle tree when it lost all of its leaves. Not being one to throw anything so cool as that bottle tree away, I simply pulled it out of the pot, beat the dirt off the roots, put it in my desk drawer and forgot about it all together.

Over a year later, I ran across it again and thought it was time to throw it away. When I pulled it out of the drawer, however, I thought the stem still looked a little green. Thinking it had to be dead after loosing all its leaves and being in a drawer with no water or light for over a year, I wasn’t sure what to expect when I potted it up again and watered it a little. I was a little more than surprised when, within a few weeks, it started to leaf out again. Talk about forgiving!

I am not for a minute suggesting you test this theory with your B. rupestris or any other plant, for that matter. What I am suggesting is you give this plant or one of any number of Brachychiton species a try. Most pachycaul species naturally lend themselves to bonsai treatment. I have recently replaced that original B. rupestris with a new plant and will be a bit more gentle when it naturally looses its leaves this time.