The Yegetatiox of Western Australia. 
liii. 
vince, or at any rate from a littoral source. Their development suggests 
that as halophytes they have been e(juipped for the dry and saline tracts 
of the Ercmea. Indeed, it may be said that they are principally developed 
in the Eremea as psammophytes or halophytes. 
Together with Eremophila, the genus Cassia assumes considerable physi- 
ognomic importance in the Eremea, being developed most extensively in 
the sandy areas. The development of an indumentum of felt has enabled 
these plants to endure extreme aridity without any loss of leaf-surface, a 
fact which is curious when it is considered that the only species of the genus 
which has invaded the marginal areas of the South-\^’est Province, has its 
leaves reduced to two or three terete segments. The desert species — 
C. clesolata and C. SiMrtii — are examples of the plants which, endowed with 
a thick felted indumentum, have, without any reduction in leaf-area been 
not only able to exist here, but become increasingly important in the more 
arid regions of the north, extending into the steppe formation. 
Perhaps the most remarkable tree of the Mulga country, and of the 
Eremea generally, is the Kurrajong {Brachychiton Gregorii). This tree, which 
attains to a height of seven metres, has the spreading branches and dense 
leafy crown of Platanus^ which it somewhat resembles ; its large bright green 
broad leaves are partially or completely deciduous, and its trunk and roots 
store water which is used in periods of excessive drought, at the time when 
leaf-fall takes place. It is an alien aristocrat of the Eremea, cpiite unlike 
any other growth form, and while of undoubted palaeotropic origin, has 
extended as far south as temperate latitudes. It is still in evidence at Westonia, 
Bullabulling, and at Lake Lefroy near Widgiemooltha. 
The number of palaeotropic elements amongst the undergrowth of the 
mulga bush is surprisingly large : examples are Breweria^ which extends 
also into the northern parts of the South-West Province, Tecoma, Justicia, 
Plectronia, Pomax, Hibiscus^ Gossypium, and amongst the lianes, Marsdenia, 
Parana, and Pentatropis. They are found principally in the shade of the 
larger species, often clustered round the stems (especially Ruellia), or in stony 
soils. 
Most, if not all of the woody elements of the mulga bush, possess seeds 
remarkable for their longevity. The seeds of some species of Acacia, for ex- 
ample, may lie in the soil in a viable condition for upwards of a century — a 
factor of considerable importance when we consider the capricious nature 
of the rainfall and the periodic desiccation by drought which characterises 
the region. In addition, the species of Acacia, unlike those of more favoured 
regions, produce their blossoms shortly after rain falls. Blossoming may occur 
twice in the same year, or on the other hand, it may be withheld for a number 
of years. There is thus no regular flowering season for the species of this 
genus, while on the other hand, the species of Eremophila and Prostanthera, 
Dodonaea, etc., appear to have prolonged regular seasons. In fact, the species 
of Eremophila bear at least some flowers almost throughout the year. 
The wealth of the ephemeral flora of the mulga country is one of the 
most remarkable of its characteristics. The formation is typically one of 
widely spaced shrubs with bare exposed soil, but after suitable winter pre- 
cipitations the whole area is carpeted with an amazing wealth of annual herbs 
which cover it with colour. These consist mainly of Compositae : wide 
stretches of Helipterum splendidum and Cephalipterum Drummondii in the 
alluvial soils appear from a distance like patches of freshly fallen snow ; the 
sandy areas are carpeted with Cala?idrinia, Erodimi, the handsome rose-pink 
Velleia rosea, purple Bellida, the gold of Helipterum Battii and H, Charsleyi, 
