121 



Sclerolcem diacantha, some withered composites, a grass, and 

 other annuals. Around our camp on Feb. 3 a fewer number 

 was seen. 



The depauperization of species is not altogether attributable 

 to the absence of soil, for long before the crystalline limestone 

 forms the surface of the ground, reduction of size and dis- 

 appearance of species is observable. The main cause must be 

 hygrometric. Rain when it falls must rapidly pass away by 

 absorption over much of the area, or by evaporation from the 

 less pervious surfaces, which, judging from the extreme dryness 

 of the air must be very active, but the rainfall is certainly very 

 small, and precipitation of dew barely possible. That the 

 vegetation has a struggle to maintain itself against such adverse 

 conditions is evidenced by their stunted growth, absence of 

 flowers or fruit, and generally by the blackened, and decayed 

 or decaying appearance that it presents as a whole. Grass in 

 most places was recognised by blackened spots on the surface, 

 whilst the numerous dead or partially leafless shrubs attested 

 to the long period which had elapsed since sufficient rain had 

 fallen to produce growth, or flowers and fruits. Further, 

 whilst all the plants of the desert tracts excepting JZremophila, 

 scaparia presented no traces of flowers or fruit ; individuals of 

 the same species were met with elsewhere in different stages of 

 maturity, and the yellow straws among the blackened tufts of 

 grass bespoke a recent growth. It is probable that after con- 

 tinued rain a vigorous growth of vegetation takes place, grass 

 and other annuals appear, and for a few weeks all seems 

 verdure, but is followed by prolonged droughts, during which 

 the perennial plants only can continue to live. 



The Bunda Plateau is perhaps the least Australian in its 

 botanical features of any part of the continent. The absence 

 or fewness of species of Proteacece, Tliytnelece, Pittosporece, 

 Leguminosce, and Myrtacece make this part of ' Australia quite 

 an anomaly. One can hardly conceive of so vast a tract 

 without gum-trees, casuarinas, grevilleas, hakeas, banksias, 

 xanthorra^as, pimeleas, xerotes, ferns, &c. The desert character 

 of the flora is indicated by the numerical strength, either of 

 individuals or species of CJienopodiacece,. such as Kochia, 

 Pliagodia, and Atriplex, Composite?, Eremopliila, &c, and by the 

 absence or rarity of Proteacece, Myrtacece, Epacridece, &c. 



List of Species of the Bu>T)A Plateau. 



Note. — The species marked by an asterisk have not yet been discovered 

 beyond the limits of this region. Those marked thus f, are recorded for the 

 first time as occurring within South Australia ; or are not included in 

 Schomburgk's Flora of the Province. 



Order Crucifer^:. 



* t Blennodia Richardsi, F. M. (Richards.) 



