The boab trees are icons of the Kimberley, Western Australia. They have bizarre, twisted leafless branches during the dry season and wreathed with brilliant green during the wet season. Boab trees are found throughout much of the Kimberley region of W.A. and the neighbouring Victoria River region of the N.T. They attract attention because of their striking and unusual shapes.
Large, showy, cream, fragrant flowers occur usually during the summer and autumn months. They open early in the evening and are pollinated that night. Each flower lasts for only a day or two before falling.
Individual flowers are short lived and are pollinated at night, mainly by hawkmoths. Fruit bats, possibly other bats and birds also visit the flowers but seem to have little involvement in pollination.
During the dry season, they lose their leaves and leave behind massive nuts. These nuts are either oval or round in shape.
The scientific name of the Australian boab tree is Adansonia gregorii, (Family : Malvaceae). It is related to the Madagascan and African Adansonia species known as baobabs.
There are 9 species of Adansonia in the world. Of the 9 species, 6 are native to Madagascar, 2 are native to mainland Africa and Arabian Peninsula and one is native to Australia. They have similar bottle-like appearances. The Australian boab trees and the African and Madagascan boabab trees might share a common ancestor as Africa was joined to Australia in Gondwanaland around 65 million years ago. As 6 species are native to Madagascar, this may depict geographical isolation can lead to divergent evolution and speciation.
Back in the ancient times, the boab was seen as a proud and arrogant tree and the Dreamtime spirits pulled the boab trees out of the ground and stuck them back into the earth upside down. The twisted branches might be actually the twisted roots.
The Aborigines of the Kimberley Region regard boab trees to have strong spiritual significance as well as many other uses.
The central wood pulp is spongy containing water. It can be a source of life saving water.
The leaves and sapling tap roots are edible and very nutritious. Pulp from the seed-pod is high in vitamin C. The seeds can be eaten raw or roasted. Edible Australian plants are called ‘bush tucker’.
The fibrous inner bark can be used for rope, baskets and nets.
A red dye is made from the outer layer of tree roots. The bark is also used to treat fever, as it contains properties similar to quinine.
The empty seed-pods can be used for storage, and also carved for ceremonial purposes.
When the dark surface of the boab fruit is scratched away it reveals a light colour underneath. Motives include native animals like snakes, kangaroos, emus, tortoises, boabs trees, landscape are commonly carved onto the fruit.
The fruit can also be painted with dots of various colours.
The colour, size and hardness of the nuts depends on the location of the tree. They are good souvenirs for tourists to take home from the Kimberley.
A mature boab tree can grow up to 15 metres and have a swollen trunk that can reach a massive girth of up to 20 metres. The age of a boab tree is difficult to determine as old tree trunks are hollow and have no annual rings. Experts have suggested that some of the very large boab trees could be thousands of years old.
This is the famous Prison Boab Tree near Derby at the west coast. The hollow tree trunk has a circumference of over 14 metres and the door is a metre wide and two metres high. It was used as a “prison cell” in the 1890s by the local police to lock up Aboriginal prisoners over night, on their way to Derby for sentencing.
These ancient trees are regarded as cherished individuals with unique personalities. Aboriginal people treat them with respect.
Boab trees are indeed the icon of Kimberley.
I would like to thank Ms Seanna McCune of Botanical Information Service, National Herbarium of New South Wales for her guidance and advice.
I would also like to thank Lizi (Tour Director of AAT Kings) for her wonderful organisation and dedication to her job. Her passion about the beauty of Kimberley and the culture of the Aboriginal people is inspiring. I also wish to thank Warren the driver who took good care of all of us during the tour. Both Lizi and Warren made our trip of the Untamed Kimberley safe and highly enjoyable.
Further readings :
https://en.wikipedia.org/wiki/Adansonia (with photos of 5 different species of Adansonia)
Deane Jill (2008) Histrees Boabgraphies Vocation Education & Training Publications WA. ISBN 978-0-9752268-9-6