The driest of the inhabited continents, Australia has 10 deserts covering 18 percent of its land mass. The largest include the Great Sandy, Gibson, Tanami, Great Victoria and Simpson Deserts. Their plants, says the South Australian Arid Lands Natural Resources Management Board, have adapted to surviving on no more than 14 inches of annual rainfall, 10 to 20 percent humidity and drying winds. In doing so, they provide food and shelter for the deserts' Aborigines and wildlife.
Waddy wood (Acacia peuce) is a small to medium tree native to the Queensland and Northern Territory edges of the Simpson Desert. Young trees are recognizable for upright greenish-gray foliage that begins drooping as they mature. Slowly growing up to 50 feet high, these trees once supplied the Aboriginal tribes and Australian settlers with timber for tools and fences. Now, however, they have an endangered status, according to the Olive Pink Botanic Garden. The most significant threats to waddy wood trees are fire, rabbits and grazing livestock.
Desert oak (Allocasuarina decaisneana) is an exceptionally long-lived tree, according to the Australian Broadcasting Corporation (ABC). One theory accounting for their age is that each of the trees’ inner rings corresponds to a rainstorm. In the Australian deserts, however, indefinite periods ranging from hours to years may separate rainstorms. Immature desert oaks have thin, columnar profiles that become broader and bushier over 20 to 30 years. The oaks’ deep taproots can extend as far as 100 feet underground to reach the desert water table.
Desert quandong (Santalum acuminatum) is a parasitic plant that depends on desert oak for its survival. In addition to its deep taproots, desert oak has a network of horizontal roots closer to the soil's surface. Desert quandong gets its nutrients from these horizontal roots, according to the ABC. A shrub or small tree, desert quandong produces edible red or yellow fruit. Mixed with water, the dried fruit pulp is a Vitamin C-rich dietary staple for Aboriginal tribes.
Sturt's Desert Pea
South Australia's floral emblem, Sturt's desert pea (Clianthus formosus) is a spreading, low-growing perennial with downy gray leaves. The foliage hairs are a moisture-retaining adaptation. During spring, desert pea’s stems have stalks bearing clusters of unusual bright red flowers. Their uppermost petals emerge from black pea-like swellings around which the other petals center. Flowering is heaviest following rain. The plants tolerate light frost as well as the desert's soaring summer temperatures, according to the Austrian National Botanical Gardens. In milder climates, the plants may blossom into the summer.