Flaxleaf Fanpetals discovered in Darwin
Staff from the Northern Territory (NT) Herbarium were recently involved in a collaboration to document the occurrence of an apparent new species of introduced plant in the Darwin region.
Herbarium Research Associate Kym Brennan asked for assistance (a rare event for anyone who knows Kym 😊!) from Herbarium staff to identify a plant he had encountered in early January from a rehabilitation area in Casuarina Coastal Reserve.
From the initial photos of the quite attractive white and maroon flowers, the previously unknown plant was suspected to be a species of Sida (also commonly known as Flaxpetals not currently recorded from Australia. Staff from the Herbarium attended the detection site with colleagues from NT Parks and Wildlife, Weed Management Branch and the Australian Government Department of Agriculture, Fisheries and Forestry to obtain specimens of the plants for confirmation.
Examination of the plant specimens in conjunction with available literature pointed towards the suspected identity of the plants as Sida linifolia being correct. This species also has the common name Flaxleaf Fanpetals in the horticultural trade and on the internet. Flaxleaf Fanpetals has not previously been recorded in Australia and there are only a handful of reference specimens from overseas currently available at larger interstate Herbaria for comparison purposes. As a final means of confirming the plant’s identity, we were able to send both the images and the morphological description of the Darwin material to colleagues in Brisbane, Canberra, Sydney and Melbourne who were able to undertake comparisons with these reference specimens and support our identification.
The plant is quite distinctive when flowering with a relatively large showy white to cream flower with prominent red/maroon bases to each petal with the large central floral tube (staminal tube) bearing bright yellow stamens giving the appearance of a ‘mini-hibiscus’. The trick is catching them – evidence from both Darwin and overseas suggests that flowers only open for 1-2 hours just after midday.
Flaxleaf Fanpetals is thought to be native to the Americas and Tropical Africa and is introduced to India, Thailand, New Caledonia and Hawaii with recent evidence suggesting that it is spreading through South-East Asian countries including Malaysia and Indonesia.
Subsequent sleuthing on the citizen science iNaturalist platform turned up images of additional possible Flaxleaf Fanpetals plants from another area of Darwin photographed in September 2024. Herbarium Botanists Lou Elliott and Aiden Webb were able to confirm the presence and identity of the species from this second location on the following day.
Once the plant’s identity was confirmed, this triggered a report of a new species incursion for Australia to the interjurisdictional National Biosecurity Management Consultative Committee (NBMCC) from the Weed Management Branch. While some species in this genus (e.g. Sida acuta) are declared weeds in the Northern Territory, initial observations of the plant suggest that it will not have significant impact. A formal weed risk assessment will be undertaken by the department.
While this plant is not on any lists of plants identified as significant new weed threats, documenting new invasions is an important part of understanding the way new plants arrive in Australia and informs our ability to mitigate the impact of plant invasions.
The Herbarium would be appreciative receiving further records of the Flaxleaf Fanpetals to further build our understanding of its distribution in the NT. This detection illustrates the important part that herbaria play in the ‘biosecurity pipeline’ where the first step in responding to a potential incursion is confirming the correct identification in question. Having a verified and authoritative collection of reference material – or a network of willing colleagues to be able to draw on – significantly increases our ability to respond rapidly to incidents of this nature.
