Shark Bay’s Tree Heath
The tree heath is the most diverse and complex plant community in Shark Bay found in the ‘overlap’ between two major botanical provinces, the South West and the Eremaean. It contains about half of the flowering plant species endemic to Shark Bay. The plants of the tree heath are valuable in understanding how species adapt to different environments and the factors which limit plant distribution and abundance. The tree heath occurs nowhere else in Western Australia and was a factor in Shark Bay being declared a World Heritage Area, and features some rare and priority species.
Eucalypts, Proteacae and other plants from the woodlands of temperate southwestern Australia mingle with the Acacia, samphire and spinifex scrublands of the desert. This heathland features scattered trees no more than 6 m high, such as one-sided bottlebrush and dune wattle, interspersed with species of Eucalyptus, Lamarchea and Eremaea. The understorey features Hakea, Calytrix (starflower), Baeckea, Scholtzia, Pityrodia and Melaleuca, plus numerous herbs and grasses.
Another feature of tree heath is the presence of unusually large forms of shrubs, a phenomenon some botanists have called ‘gigantism’. Heath species such as Ashby’s banksia (Banksia ashbyi) and Shark Bay grevillea (Grevillea rogersoniana) have exceptionally large specimens in Shark Bay, at the northern limits of their range. The reasons for the presence of these ‘giant’ shrubs are not fully understood.
Tree heath extends from the southern parts of Nanga and Tamala Station down to the inland section of Zuytdorp Nature Reserve. For example, it can be seen on the road to Useless Loop, about 25 km from the Shark Bay Road turnoff.
Clcik here for a map of the area.
Special plants found nowhere else
A large number of plants are restricted, or almost entirely restricted, to the tree heath community. These include:
- Beard’s mallee (Eucalyptus beardiana), an endangered species;
- Shark Bay grevillea (Grevillea rogersoniana), a priority species;
- The wattle Acacia drepanophylla, a priority species;
- The herb Macarthuria intricata, a priority species;
- Shark Bay featherflower (Verticordia cooloomia), a priority species;
- Shark Bay mallee (Eucalyptus roycei);
- Prickly woollybush (Adenanthos acanthophyllus); and
- Hakea stenophylla.<
Beard's mallee (Eucalyptus beardiana)
What is a ‘priority species’? Click here to find out. You can also learn more about Shark Bay’s rare and endangered species here.
For more information about Western Australian plants check out the West Australian Herbarium’s FloraBase.