The Castanospermum australe, or Australian Chestnut, stands out with its majestic presence and resilience. Native to the coastal regions of Australia and New Guinea, this tropical tree enhances landscapes with its dense foliage and elegant, upright growth. It often reaches an impressive height of 20 metres, making it an iconic feature of tropical environments. Its long, dark green leaves, arranged alternately with a feathery texture, add a refreshing and naturally sophisticated touch to green spaces.
Each spring, this tropical tree bursts into bloom with stunning clusters of red-orange flowers. These blossoms attract a wide range of pollinators and birds, helping to enrich the biodiversity of its surroundings. Following the flowering period, large woody pods appear, containing black seeds known as black chestnuts. These uniquely shaped seeds often intrigue visitors and spark curiosity.
The Castanospermum australe, or Australian Chestnut, thrives in well-drained, nutrient-rich soils. In Ivato, near Antananarivo, it finds an ideal habitat in the botanical garden of Au Bois Vert. Additionally, its ability to provide dense shade makes it a popular choice for outdoor spaces in hotels, restaurants, and lodges across the region. At the same time, it plays a key role in the aesthetics and design of these spaces, creating a serene and tropical atmosphere.
Beyond its ornamental appeal, this tree actively contributes to the local ecological balance. Its flowers provide nourishment for pollinators, while its lush foliage offers a natural refuge for many bird species. Visitors to the botanical garden admire its beauty and numerous qualities. By incorporating this tree into its landscapes, Au Bois Vert strengthens its commitment to biodiversity conservation while offering a place of wonder and discovery for its guests.
Plant use
The Castanospermum australe is much more than just an ornamental tree. Its seeds, although toxic in their raw state, hold cultural and historical significance. Australia's Indigenous peoples have long used these seeds as a food source, first boiling and leaching them to remove their toxic compounds. These practices highlight the deep ecological knowledge of local communities. In traditional medicine, certain parts of the Australian Chestnut tree are valued for their medicinal properties. Extracts from its seeds have shown potential effects against certain viral and bacterial diseases, though further research is needed to confirm these applications. Beyond its traditional uses, the Australian Chestnut plays a key role in landscaping. Thanks to its dense foliage, it is often planted to provide shade in both public and private spaces. In botanical gardens such as Au Bois Vert, it serves as a major attraction, captivating visitors with its natural beauty and fascinating history. This tree is also highly valued in hotels and restaurants around Ivato for its calming presence and tropical aesthetic. The wood of Castanospermum australe is occasionally used for crafting furniture and artisanal objects, although this remains a niche application due to the tree’s ecological importance. Lastly, it is appreciated as an indoor plant when grown in pots, bringing an exotic touch to any space. At Au Bois Vert, the Australian Chestnut perfectly embodies the balance between aesthetics and sustainability. Its presence in the botanical garden showcases efforts to preserve and highlight iconic tropical species for visitors to Antananarivo.
Key information
| Common name | Australian Chestnut |
| Scientific name | Castanospermum australe |
| Origin | Australia and New Guinea |
| Natural habitat | Tropical coastal regions |
| Life cycle | Perennial |
| Flowering period | Spring |
