The first records of naturalisation of an unusual tree have very recently been made in coastal south-east Queensland.
The autograph tree (Clusia rosea) is a small, crooked-trunked tree reaching about 8 m tall, with very large and conspicuous dark glossy green, paddle-shaped leaves. When broken, stems and leaves exude a copious yellow sap, that hardens into a resin-like substance, that is mildly toxic.
The plant is named from the curious fact that leaves can be written on using a pencil, and the resulting message remains like green calligraphy on the living leaf, so long as the thick leaf persists.
The pink and white flowers are large (to 8 cm across), developing from ping-pong ball-sized buds. Larger trees can produce aerial roots, that have distinctive lenticels (corky patches) along their length. These look rather like large Pandanus stilt-roots. The large fruits split to reveal many reddish seeds.
Examples of this plant have escaped cultivation in the Coolum district and have spread into adjacent bushland. Hardworking Queensland Parks and Wildlife Service rangers have identified and removed up to 20 individuals in recent months, from the popular Mount Coolum National Park and several other nearby areas. We have them to thank as effective Weed Spotters for detecting this new weed species.
Clusia rosea has been clearly demonstrated to invade coastal plant communities in the Hawaiian Islands of Maui, Oahu, Kauai, and the Big Island, and has become weedy in some Sri Lankan ecosystems. There is also evidence of weediness in parts of South Africa. The species is problematic, as it can germinate high in the forks of trees, and become hemi-epiphytic, sending down roots that eventually strangle the host tree. This arboreal habit makes it difficult to detect, and therefore harder to control than most other tree weeds on the Sunshine Coast.
Many people are now looking for this newly invading plant species across coastal Queensland, including QPWS rangers, habitat restoration workers, professional botanists, and local council Bushcare officers. The species is not listed as either restricted or prohibited matter under the Biosecurity Act 2014. However, autograph tree is now proven as the latest environmental weed within south-east Queensland. Early detection and control will prove much more cost-effective than waiting for this species to become as widespread as it has now become in parts of the Hawaiian Islands.
The autograph tree is being considered for listing as a ‘locally significant’ invasive plant species under a proposed review of the Sunshine Coast Council Biosecurity Plan. Other councils may also be considering listing as part of their local government Biosecurity Plans.
If you live in coastal areas of Queensland, keep on the lookout for autograph tree seedlings or plants. Record images, record location details and contact the Queensland Herbarium on (07) 3199 7671, email a photo to Queensland.Herbarium@qld.gov.au, use the weed spotter app for Android smartphones or contact Biosecurity Queensland on 13 25 23.