Article by Rhea Phelan, vector & pest plant officer, Sunshine Coast Council
The Mexican bean tree (Cecropia spp.) is native to Central and South America. Its hollow stems provide a home for species of Azteca ants. The leaves of the Mexican bean tree are also eaten by these ants as well as sloths who take up to a month or more to digest a leaf and who are one of the few species not scared off by the ants.
The Mexican bean tree is a fast growing tree and a pioneer of tropical forests in central and south America. In Australia however, without sloths and ants to slow down its growth, it has the potential to outcompete native plants and pose a threat to riparian and rainforest ecosystems.
Mexican bean tree is considered as one of the top 100 World’s worst invasive species by the International Union for the Conservation of Nature Invasive Species Specialist Group. For this reason, Cecropia pachystachya, C. palmata and C. peltate are declared in Queensland as restricted invasive plants under the Biosecurity Act 2014 (Qld).
Due to the success of the Mexican bean tree surveillance program run by Biosecurity Queensland and Sunshine Coast Council, the tree has not yet become established on the Sunshine Coast.
A couple of trees have been found in gardens on the Sunshine Coast in Buderim, Mount Mellum and Glenview. The biggest tree with a 1 metre diameter was found on council land in Maleny. Luckily these trees were found before they were spread by bats or birds into surrounding bushlands.
If you think you have seen one of these trees please check that it fits the description provided by Biosecurity Queensland:
- fast-growing tree 10-20m tall, sometimes up to 25m tall
- leaves are alternate, 10-50cm wide, resemble paw-paw leaves
- lower leaf surface is densely covered with white hairs
- leafstalks are usually 23-30cm long
- hollow stems, flowers and fruits are key features
- yellow flowers are arranged in clusters of spikes, 12-18cm
- fruit is cylindrical, ovoid to oblong-ovoid, somewhat flattened, 3.3-3.7mm long, with soft, sweet flesh around many small seeds.