Adansonia gregorii—often called the Australian baobab or boab—is a unique species native to the Kimberley region in Western Australia and parts of the Northern Territory. It’s the only baobab species found in Australia, while other baobabs are native to Africa, Madagascar, and parts of the Arabian Peninsula.

Adansonia gregorii has the characteristic swollen, bottle-shaped trunk typical of baobab species, although it tends to be smaller than its African relatives. Mature boabs can reach about 10–15 metres in height and have thick, often bulbous trunks that can grow several metres in diameter. The trunk is smooth, greyish, and swollen, especially at the base. The canopy is sparse, with branches extending outward in a way that sometimes gives the tree a unique “upside-down” look, as if the roots were in the air.

Boabs are deciduous, dropping their leaves in the dry season. In the wet season, they produce large, white flowers with a unique, crinkled appearance. These flowers open in the evening and are pollinated by moths and small mammals. The fruit is oblong with a hard, woody shell and contains seeds embedded in a dry, powdery pulp.

Edible and Medicinal Qualities

Like African baobabs, the boab tree has a range of uses:

1. Edible Pulp and Seeds: The boab’s fruit contains a dry pulp that is rich in vitamin C and can be eaten fresh or dried. The seeds inside the fruit are also edible and sometimes ground into flour or roasted as a snack.
2. Medicinal Uses: Indigenous Australians have traditionally used parts of the boab tree for various medicinal purposes. The pulp and leaves are believed to have anti-inflammatory and antimicrobial properties, and the bark has been used to treat fevers and digestive issues. However, scientific studies on these medicinal properties are limited, so these traditional uses are largely based on cultural knowledge.
3. Water Storage: Like other baobabs, the boab stores water in its trunk, making it an essential resource in the arid regions of northern Australia. While not typically tapped for water, its unique capacity for storing moisture is crucial for its survival.

How Did It Arrive in Australia?

There’s still some debate about how the Australian boab arrived. One theory suggests that it might have been carried by ancient ocean currents or dispersed by early human travelers or animals. Another possibility is that it shares a common ancestor with African and Malagasy baobabs, from a time when Africa, Madagascar, and Australia were part of the supercontinent Gondwana. As the landmasses drifted apart millions of years ago, different species evolved independently on each continent.

Growing Adansonia gregorii from Seed

If you’re interested in growing a boab tree from seed, here are the steps:

1. Seed Collection: The seeds are found inside the boab’s fruit. They are hard, oval, and encased in a dry, fibrous pulp.
2. Preparation: Boab seeds have a tough shell, so gently scarify them by rubbing them on sandpaper or nicking them with a file to aid germination. Alternatively, you can soak them in warm water for about 24 hours to soften the outer shell.
3. Planting: Plant the seeds in a well-draining soil mix (a cactus or succulent mix works well) in a pot at least 20–30 cm deep to accommodate the taproot. Boabs grow best in warm, sunny environments, so choose a location that receives plenty of light. Ensure the soil is kept moist but not waterlogged. Avoid over watering, as boabs are highly drought-resistant once established.
4. Care: Boab seedlings are relatively slow-growing but will begin to develop their characteristic thick trunk over time. In Australia, boabs can thrive outdoors in tropical and subtropical regions, but they may need some protection in cooler areas. Fertilize sparingly and ensure the soil is well-draining to avoid root rot.

Boabs are long-lived and, with patience, can make a stunning addition to a garden, showcasing a piece of Australia’s unique natural heritage!

Picture by Whinging Pom from Everywhere, Australia, CC BY-SA 2.0 <https://creativecommons.org/licenses/by-sa/2.0>, via Wikimedia Commons