Boabs, Baobabs and Bottles

I’m in the land of the Boab, the Kimberley of northern Western Australia, and I’ve now seen my first Boabs in their natural habitat. Very exciting and worth the seven or so hours of air travel on its own.

Some are without leaves, as they are meant to be in the Barrbana or ‘dry’. Others are in full leaf, as seems right given all the rain…

Three years ago I chatted with Simon Marnie on ABC Radio about how do you tell a bottle tree from a boab, or indeed a baobab? This was pre-blog so I’ll repeat my notes here.

Firstly, the much loved ‘bottle trees’ in the Royal Botanic Gardens are Queensland Bottle Trees, a species of Brachychiton.

Brachychiton also includes the Illawarra Flame Tree and Kurrajong, often with slightly swelling trunks, and many of the species are on display in the 11-year old Kurrajong Arboretum at Mount Annan Botanic Garden.

Brachychiton rupestris, the Queensland Bottle Tree, is quite restricted in its natural distribution, from central to southern Queensland. The common name has a dual meaning as water is stored in the trunk, and the tree trunk looks like a bottle.

The bark itself is quite odd in being green in parts, and photosynthesising like a leaf (helpful when the plant sheds its leaves in late spring, just before flowering).

We often get asked what the difference is between bottle trees and baobabs - or boabs.

Baobab is the common name given to the genus Adansonia, in a different family to Brachychiton but in a similar part of the flowering plant evolutionary tree. There are only six species of Adansonia, four of them in Madagascar, one on mainland Africa and one in Australia.

The famous Dr Livingstone compared trees of the mainland African species, Adansonia digitata, to giant radishes, carrots and parsnips.

In Australia we often lazily drop a few letters and call our species the Boab. Adansonia gregorii grows only in tropical Western Australia and Northern Territory.

We have tried to grow the Australian boab in the botanic garden, but so far unsuccessfully due its dislike of Sydney’s winters. However you occasionally see one of the African species thriving in this region.

Australia’s most infamous Adansonia is probably the Prison Boab near Broome, which was used as to imprison Aboriginal people a century ago – prisoners were chained up inside, or in the shade, of the tree (depending on who tells the story). It’s reputedly 1500 years old.

I finished my chat with Simon by commenting that until we succeed in getting a boab growing, you can enjoy our elderly Queensland Bottle Trees, or watch one of our newest bottle tree acquisitions, a 6-year-old, settle into its prime location near to the Opera House gates.

You could also visit the Kimberley.

Images: Boabs from near Derby, starting with the Prison Boab.