The South Australian Naturalist. 
119 
among the sand. On the West Coast there are several spots 
where the same thing has happened. Tlie sandhills near 
Elliston, denuded of their natural covering, began to drift and 
cover good soil. At great expense Marram grass was estab- 
lished and the sands are held. 
Plants require live things to enable them to grow. These 
are: — (1) Water, (2) warmth, (3) food, (4) air, (5) light. 
Plants do not get moisture from the rain, as \ve catch, water 
in tanks, but by absorbing the water held round the grains of 
soil, in the finest soils the particles .in the soil may liave a sur- 
face of as much as 3 acres in one cubic foot. In the 
sand this surface is a great many times less. .Experiments go to 
show that plants require immense quantities of water, 
amounting probably to 250 times the weight of the plant 
when thoroughly dried. Not only does the sand hold very 
little moisture, but it also has very little humus. Hence 
every plant flourishing on the sandhills must have means 
of getting its necessary supply of moisture from a nig- 
gardly soil, and this it does in many ways, but chiefly by 
producing an immense growth of roots. Many plants store 
up water in special cells (miniature tanks). The sand be- 
comes heated very quickly, and at night cools no less 
quickly. Few varieties of plants can flourish in such con- 
ditions. Some are protected by a furry outercoat, others 
by a hard skin. Every land plant requires a fixed base, 
but the sand provides only a precarious hold; here is ano- 
ther reason for the excessive root formation, and the long 
creeping stems which hold the sand so effectively. The 
moving sand, driven by the wind, acts as a sand blast, espe- 
cially within a few inches of the surface. The hairy in- 
vestiture serve's to protect the delicate tissues of the plants. 
Some leaves, like that of the common grass of the sandflats 
(Sporobolus) are curled up to protect the openings in the 
leaves. In other plants these openings lie in deep pits 
covered with a dense coating of short hairs. Sandhill 
plants on all the temperate coasts of the world have to meet 
i somewhat similar conditions, and hence in all countries 
there is a great resemblance in the flora, only hardy plants 
with special adaptations flourishing on the dunes. 
