May, i942 The Queensland Naturalist 29 
only gentle undulations. Sand is a substance which is 
easily shifted by wind, and as winds are frequent, there 
is the possibility of huge unstable areas. Under these 
circumstances, few plants can establish themselves. Once 
a plant has established itself, however, some degree of 
stabilisation of the sand is effected, and other plants 
appear, until a more or less definite though very open 
plant-cover appears. The crests of the dunes are never 
vegetated though the sides may be. In the Arunta Desert 
one of the most characteristic plants of the lower slopes of 
the dunes is the 4 4 Sandhill Canegress” ( Zygochloa para - 
doxa). This is a densely shrubby grass about 3-4 feet high 
with long creeping underground stems as well, and is a 
most effective sand-binder. On the lower slopes also, a 
profusion of brilliantly coloured flowers appear after rain 
— white, yellow, lilac, pink. Very large areas of sand- 
desert occur in Western Australia. 
In the second type, Stony Deserts, the surface is com- 
posed of a layer of boulders of various sizes (l have seen 
them as large as a man’s head) or occasionally of sheet 
rock. These deserts seem, on the whole, to be more sterile 
than sand-deserts, though in Australia they grade imper- 
ceptibly into better country. In Australia they are fre- 
quently called 4 4 gibber plains.” Sturt’s Stony Desert on 
both sides of the Queensland-South Australia border 
belongs to this type. The rock fragments or 4 ‘gibbers” 
overlie an orange-coloured soil, and sometimes may not 
completely cover the soil. Shrubs and small usually 
crooked trees occur here occasionally, particularly on 
slopes, commonly species of Acacia and Erernophila. The 
most interesting are the fairly widely spread Erernophila 
Lair oh ei with showy crimson flowers, and the rare 4 4 waddy- 
wood” ( Acacia Pence), with the heaviest but one of all 
known timbers. Smaller plants are mostly grasses and 
members of the salt-bush family, many of them annuals. 
In some parts of the Australian stony deserts, but 
more particularly in the sandy deserts, the so-called 
44 spinifex” is prominent. The name, which has nothing 
to do with the botanical Spinifex, is applied to the 
numerous species of Trioclia and Plecirachne. These are 
two genera of grasses of peculiar appearance. They form 
large more or less hemispherical masses up to 9 feet in 
diameter and up to 4 feet high, with stout spinelike leaves 
