96 PLANT HABITS AND HABITATS IN THE 



SIZES AND FORMS OF LEAVES AND PHYLLODIA. 



Measurements were made of the sizes of the leaves and phyllodia 

 of some of the woody perennials growing about Tarcoola and Port 

 Augusta. It was found that these fall into two well-marked groups, 

 namely, those relatively wide and those relatively long. In the former 

 case the relation of width to length is about 2.2 to 1, and in the latter it 

 is about 1 to 15.4. The average breadth of the leaves and phyllodia is 

 about 2.8 mm. in the former and 6.8 mm. in the latter. The average 

 length is 42.8 mm. and 14.8 mm. in the two classes of leaves or phyllo- 

 dia, respectively. The foregoing measurements refer to Tarcoola 

 plants only. So far as those from Port Augusta are concerned, it was 

 found that the narrow type had the following averages: length, 66.3 

 mm.; breadth, 4.8 mm., giving thus a ratio of length to breadth of 

 about 13.8 to 1. A noteworthy feature in the ecology of these plants 

 is that species with narrow type of foliage may occur both along 

 streamways, where the water conditions are relatively good, and also 

 away from the washes, and hence amid more arid surroundings. A 

 more detailed account of the sizes and form, as well as other characters 

 of the foliage of the Port Augusta and Tarcoola plants, appears on 

 pages 111 to 113. 



VEGETATION AND ENVIRONMENT AT QUORN. 



The regions represented in this reconnaissance of the most striking 

 features in the perennial vegetation of the drier portions of South 

 Australia are, according to the terminology here adopted, desert, arid, 

 or semi-arid. Oodnadatta and the Lake Eyre Basin represent the 

 first; Copley and the southwestern portion of the state the second; 

 and Quorn the last. To the latter, however, may be added the mallee 

 region around Blanchtown. There is thus a progressive series so far 

 as the rainfall is concerned. Naturally, and in a manner closely 

 paralleling the increase in rainfall, there is an increase in the amount 

 of vegetation, with a gradual creeping in, as one progresses from the 

 more arid to the less arid regions, of forms less well adapted to with- 

 stand the rigors of intense aridity. There is an increase in the number 

 of species as well. 



To adequately describe as a whole the flora of any of these regions, 

 not to say those with the greatest rainfall, would be a very serious un- 

 dertaking. This, as I have already pointed out, is not the object of 

 this study, which aims rather to investigate types of representative 

 plants and their adjustment to the surroundings in which they are to 

 be found. Although I have pointed this out in the introductory portion 

 of the study, it seems well, in order that there can be no misunderstand- 

 ing, that I refer to it again. This is particularly necessary, inasmuch as 

 the flora at and about Quorn is especially rich and the treatment of it 

 to follow makes no pretense of completeness. 



