Wildflowers-What is a ‘Good Season’?—Main Club October Meeting Report

In October the main branch was lucky to get Greg and Bronwen Keighery along to talk about WA wildflowers, the focus of their working lives since the 1970s. Greg has worked as a scientist for Kings Park and WA government (CALM, then DPaW, and now DBCA i.e. Dept. Biodiversity, Conservation and Attractions) and Bronwen as a teacher and an EPA (Environmental Protection Agency) and also private consultant botanist—notably on the Swan Coastal Plain.

Western Australia is world famous for the number and diversity of its native wildflowers. Here we have the whole gamut from superb flowering trees, shrubs, orchids and herbs with taxa now numbering around 17 000. The state is a third of Australia’s area and contains tropical, arid and temperate areas, each with their own suite of wildflowers. The topic of the talk was where and when can they be seen? And what is a good season?

But firstly—what are ‘wildflowers’? Is it the golden balls of Nuytsia floribunda (WA Christmas Tree) at Windy Harbour, or the bunch of gazanias on a roadside?

One of the first requisites for a good season is rainfall: its timing, duration and amount. Western Australia has 27 bioregions found in three districts: Kimberley, Desert and Southwest. The Kimberley has summer rain, the Desert has erratic rainfall and the Southwest gets winter rain.

Another determinant is geology and soils. WA has very old soils (270 million years for most of the state) and thus they are nutrient poor. The landscape is generally flat. The soils vary widely from sand to clay to rocky (limestone, laterite, ironstone and “granite”) but support a rich flora, a high diversity peaking around Mt Lesueur, Stirling Range and the Perth area (this latter area has only recently been recognized). There are numerous ways plants overcome poor soils. Examples were shown of haustoria* from Nuytsia attached to sedge roots (it is a hemi-parasite).

The Kimberley District reaches its greatest diversity in the wet (when it is often not accessible) with some 150 species of grasses some of which grow to well over head height. The presence of drier, typically upland areas and wet clay flats increases the diversity. The species growing in water change as the water level dries up e.g. Nymphioides indica.

The desert areas have erratic rainfall with many grass species, Asteraceae and Acacia. Grevillea wickhamii is outstanding. A Calandrinia found at Kirkalocka has tuberous storage roots enabling a mass display in November. Granite rocks support a range of unique plants such as the Stylidium scintillans on rocks near Paynes Find.

The Southwest has a much longer flowering season e.g. Acacias have a sequence of species flowering over a long period of time. Even in dry years there will be flowers. Hot fires which boost the soil nutrients can cause a burst of flowering the next season. The fields of flowers we associate with everlastings in drier areas also occur in this area. We were shown clearings in the southwest covered with Podothecas (yellow Asteraceae) and another of Waitzias in a Wandoo forest; Lake Muir has fields of everlastings  Grasses such as the Austrostipa elegantissima are present. Often wetter and drier areas are adjacent with the consequent diversity in a small area.

Trachymene coerulea (Swan River Lace Flower) is an interesting annual on Rottnest and Garden Islands: it grows each year from seed but in other areas it needs fire. Fortunately European botanists took seeds from the islands to send to Europe where it was propagated and is one of the most widely grown native plants there.

Where can we find the wildflowers? Look for a patch of bush, walk in and look. Google Earth can help pick out promising areas. Survey the Bureau of Meteorology records the past few months to find possible areas of desert flowers. Go to Florabase and search by shire and set months to find what is flowering. Along the mulga/eucalyptus line is the everlastings area—especially if there have been good rains.

A good map of areas is needed—the Wildflower Society used to do this with support from the Tourist Bureau. Some Shire Visitor Centres do have information (notably Dalwallinu.) Unfortunately no two seasons are the same and the clearing of land and road verges (even where there are priority flags) still occurs.

A question from the audience about productive use of our flora had Greg discussing a project for growing Platysace as a root vegetable. A sweet product was grown experimentally in sufficient quantities in natural soil—but no one was prepared to back it.

In conclusion, the Keigherys stated that wildflowers are the basis of our tourist industry. We need to advertise them and extend the knowledge of them from the fields of everlastings to the huge array of our unique plants—their intrinsic beauty and their many adaptations (e.g. pollination, poor soils and the South West’s hot dry summers.)

Margaret Larke

*A specialized structure of a parasitic fungus or plant, used to absorb nutrients and water from the host plant.