The Great Sandy Desert, says Australia's Department of Environment and Natural Resources, is a vast expanse where red sand plains and dunes can stretch to the horizon. Covering more than 110,000 square miles of western and northern Australia, it has two climate zones. The northern desert has an arid tropical climate, while the south is temperate and subtropical. Rainfall across the desert averages just 8.77 inches per year. The sparse moisture limits the desert's plant life to a few very tough shrubs, trees and grasses.
Parkinsonia (Parkinsonia aculeata), says the Australian Government, is a prickly bush that can grow 26 feet high. Its multiple stems have flat, narrow green leaves up to 11 inches long. Sharp curving pines guard the leaves' bases. A shallow-rooted bush, Parkinsonia has three-quarter-inch flowers with four drooping yellow petals, and a single standing orange or orange-splotched petal. Brown or olive-green oblong seed pods follow the flowers.
Parkinsonia normally flowers in the winter and drops its seeds in spring, but mature plants may bloom at any time. Seeds can survive for years, germinating in hot, wet weather. Settlers introduced the plants as ornamental hedges, but they have naturalized throughout northern Australia. They grow wild along streams and rivers, thriving in wet clay soil but also tolerant of hot, dry conditions. Unchecked, parkinsonia forms thickets that choke out all other plants.
Hummock grasses (Triodia) are the dominant plants of the Great Sandy Desert's dunes. They tolerate the desert's infertile sand plains and arid conditions, according to the Australian National Resources Atlas and McQuarie University. Also called spinifex or porcupine grasses, they form large domes with green exterior leaves. Their centers contain dead leaves and heavy mats of stems. Soft when new, the leaves stiffen and curl as they mature. The largest hummock grasses can be more than 6 feet tall and up to 9 feet wide. Some plants appear as rings when their dead centers collapse, leaving only a circle of outer leaves.
White Dragon Tree
The northern desert's Dragon Tree Soak is a 12-acre swamp with a fresh-water spring. It lies in the midst of a white dragon tree (Sesbania formosa) woodland, according to the Australian Natural Resources Atlas. While this tree usually stands from 25 to 40 feet high, some specimens reach 65 feet. A rapidly growing perennial, white dragon tree has upright branches and white flowers. It's useful for shade, erosion control, and as a privacy fence. The trees young leaves and seedpods are edible, says the United Nation's Food and Agriculture Organization.