Scientific name: Aponogeton bullosus
Conservation status: Aponogeton bullosus (A. bullosus) is listed as Endangered in Queensland (Nature Conservation Act 1992) and nationally (Environment Protection and Biodiversity Conservation Act 1999). It is considered a high priority for conservation under the Department of Environment and Heritage Protection Back on Track species prioritisation framework.
A. bullosus is a tuberous plant that reproduces more than once and lives for more than one year in freshwater aquatic environments. The enlarged fleshy stems (tubers) take root in the sand on rocky stream beds. Leaf clusters emerge from the top of the tuber, are mostly submerged, and have a crinkled and bubbly appearance (This leaf form is known as ‘bullate’, hence the name ‘bullosus’). Leaves are lance-shaped, narrow, semi-transparent, have prominent leaf veins and range from 7-30 cm in length. Flower stems are 8-30 cm long and produce yellow, cone-shaped flower spikes which are often submerged. Fruits are elongated, have a short beaked top, and are 5-6 mm long and 3-4 mm wide.
Habitat and distribution
This species occurs in shallow, cool, fast flowing rivers and streams, on granite sand surfaces. A. bullosus is restricted to north-eastern Queensland, from Innisfail to the Atherton Tableland.
Life history and ecology
Flowering and fruiting in A. bullosus occurs between June and October. Flowers may emerge above the waters surface for a short time for pollination and fruits then develop underwater.
Weeds are a major threat to this species. Encroachment of exotic weeds in the riparian zone, such as Paramatta grass (Sporobolus africanus), water lettuce (Pistia stratiotes), elephant ears (Alocasia sp.) and other invasive water weeds, compete with A. bullosus and degrade its habitat.
Illegal collection for the aquarium trade is also a major threat to this species. This plant is highly desirable and is used for the ornamental value of its bullate (blister like in appearance) leaves. A. bullosus now appears to be restricted to a single population and as it is a difficult to maintain in cultivation, demand for replacement plants threatens the wild population.
In the Innisfail area, habitat for this species may be under pressure from development. It is also important to maintain a riparian strip of vegetation to provide shade over the stream, as the species appears to prefer areas where there is good canopy cover along streams.
What can you do to help this species?
- Do not collect A. bullosus plants or plants of other threatened Aponogeton species from the wild.
- Eradicate exotic weeds from habitat supporting threatened Aponogeton species as these weeds may degrade habitat and compete with and possibly exclude native species.
- Prevent the introduction of new exotic weeds. For example, avoid dumping aquarium plants, animals, gravel or water into waterways and wetlands.
- Maintain canopy cover along streams.
Aston, HI. 1973. Aquatic plants of Australia: a guide to the identification of the aquatic ferns and flowering plants of Australia, both native and naturalized. Melbourne University Press, Carlton, Victoria.
Department of Sustainability, Environment, Water, Population and Communities (SEWPaC). 2007. Aponogeton bullosus in Species Profile and Threats Database, SEWPaC, Canberra.
EPBC Act Conservation Advice, Aponogeton bullosus, Department of Sustainability, Environment, Water, Populations and Communities, Canberra.
Stephens, KM and Dowling, RM. 2002. Wetland Plants of Queensland: A Field Guide. CSIRO Publishing, Collingwood, Victoria.
* Requires Adobe Reader