Toowoomba Field Naturalists: Speaker's Report: May 2016 meeting

Travels in the South-West Corner of Australia ( Report by Jean Gundry and Cheryl Haxen)

Ben and Jean travelled by road in August/September 2014 to WA via the Eyre Peninsula and the Nullarbor to the South-West corner of Western Australia, also known as the SW Botanical Province. Their journey took in areas of heath and shrub land vegetation in the Kwongan, a distinct and interesting vegetation zone and included visits to Cape le Grande National Park (N.P.), Fitzgerald River N.P. and the Stirling Range N.P. A farm-sit near Ongerup afforded time to explore the incredibly rich flora of the region.

The entire area forms part of the Yilgarn Craton, a huge and ancient chunk of granite rock formed 3700 -2400 million years ago. Over time the granite has eroded to deep infertile sands and the remaining outcrops, granite inselbergs, continue to crack and flake, and damp soak areas form in pockets creating an environment for a rich and diverse vegetation ecosystem. In addition, 40 million years ago the sea level was 250 metres higher than today resulting in the area being isolated for a considerable time. This isolation resulted in the evolution of many endemic species of plants. To date 8,500 species have been identified.

Harsh conditions have resulted in hardy species with adaptations for water saving and coping with the nutrient poor soils. Jean showed photographs from a number of vegetation types: the Myrtaceous –proteaceous shrublands, Coastal shrubland on granite, Banksia woodlands, Wodjil thickets, Swamp and Sedge Kwongan and the Stirling Sandstone Kwongan. As in South Africa, the Hakeas are richly represented with examples including Hakea clavata with thick succulent leaves ending in a protective spike and Hakea drupacea (sweet hakea) with needle-like leaves. In contrast she showed Utricularia menziesii (red bladderwort), a carnivorous plant of damp areas. The roots bear minute bladders which expand rapidly when triggered by movement in the water and suck in small aquatic creatures which are digested, providing the nutrients lacking in waterlogged soils. Parasitic plants such as Santalum (Quandongs) and Nuytsia (Christmas tree) have an alternative nutrient-acquisition strategy but are under-represented due to inherent risks such as dehydration and fire.

Most plants in the nutrient-poor soils of the Kwongan have non-mycorrhizal roots termed cluster roots, dense outgrowths which are designed to release carboxylates which enable the uptake of scarce phosphorus. This includes members of the Proteacaea Family which are richly represented here. One exception, Hakea verrucosa (Wheel Hakea) has mycorrhizal associations. Jean also had a number of photographs of plants in the Fabaceae (pea and bean family). Many of this family and others in these harsh environments produce toxins to discourage too much damage by herbivores. Domestic livestock is often affected but native animals have evolved resistance.

Australia is generally special in having such a large number of plants pollinated by animals other than insects, and this meant that Jean and Ben enjoyed spectacular birdwatching – Western spinebills and New Holland honeyeaters feeding on Lambertia, Leptospermum, Lechenaultia etcetera. Dryandra dallanneyi (couch honey-pot) is an exception, it flowers at ground level and is pollinated by honey possums.

There are also problem ferals like cats and even kookaburras which are an introduced species here. However much of interest remains including Carnaby’s cockatoos, Red-tailed and Baudin’s long-billed cockatoos, Elegant parrots, Purple-crowned lorikeets, Mallee fowl, bandicoots, shingleback lizards, Rosenberg’s goanna and the Spotted Thigh frog (Littoria cyclorhyncha) endemic to the area.

WA is very rich in orchids, a highly evolved family of plants most commonly pollinated by insects. A significant number of ground orchids was photographed and Jean had managed to identify most of them. Beautiful shots of cowslip, slipper, wasp, bee and mantis orchids were shown, the last three resembling the insects for which they are commonly named. Some of these resemblances are no accident as they have evolved to attract specific insects to pollinate them sometimes by mimicking the female insect which causes the male to attempt to mate, thereby collecting pollen and transferring it to the next flower he tries to mate with. There were greenhood orchids which trap insects briefly in order to effect pollination. There is only one species known of the sugar orchid (Ericksonella sacharata) which is endemic to just a small region. It smells strongly of musky sweet cinnamon. The stunning sun orchid Eastern Queen of Sheba (Thelmitra aff. Variegata) is a widespread but infrequent inhabitant of the sand heath.

Along the way they discovered individuals and families involved with conservation of these unique habitats and plants. Near Stirling Range NP large areas were cleared post-war of what were considered worthless plants. A million acres a year was the goal. The result was erosion and salinity and there is now remediation in progress, carried out by a growing number of concerned landowners and conservation groups including Bob Brown’s Bush Heritage. Hans Lambers and the team at UWA are working hard on a bid to have the entire Kwongan area World Heritage listed, but with considerable intransigence from the current State government. Thanks to Jean for the wonderful photographs and the many hours of research which made the presentation of such varied interest.