133 The South Australian Naturalist. 



THE GEOGRAPHICAL DISTRIBUTION OF SOUTH 

 AUSTRALIAN PLANTS. 



Bj J. B. Clelancl, M.D. 



The distribution of our South Australian plants is a 

 matter ol" very considerable interest. As an example, may I 

 quote the ease of the only Geebung we i)ossess, Persoonia 

 junii3erina. Scattered plants may be met with in our hills from 

 neai- Mount Lofty to Mylor, Kuitpo, Mount Compass, and on 

 to the Waitpinga scrub near Phicounter Bay. In the Adelaide 

 district it probably occurs in a number of other localities, 

 and Tate records it for District T. (the ''90-niile desert"). It 

 is recorded for Mctoria and for the southern high- 

 lands of New South Wales. It is evidently a widely- 

 distributed species. Is there a more or less direct con- 

 nection between its South Australian habitats and its 

 Victorian ones, and do the latter connect up with those of 

 New South Wales? We do not know, for as yet no one has 

 systematically attempted to ascertain and record its exact 

 distribution. Now in Victoria there are at least eleven species 

 of Pej'soonia. in New South Wales 32, and in Western Australia 

 25. Why have we only one species in this State? Is this the 

 only remaining member of the genus, a number of other species 

 having disappeared, or does it represent a specially vigorous 

 member which in distribution has at present outstripped its 

 fellows, ])ut will be followed later by other members? What 

 an interesting study this species will make when we know 

 reasonably accurately its actual distribution in the three States 

 as well as the areas occupied by its fellow species. So much 

 for an example of an interesting species, and there are un- 

 dou])tedly very many more of equal interest, did we only know 

 something of their distribution. 



There has recently been propomided a new theory of plant 

 and animal distribution, termed the theory of **age and area," 

 for which the authors claim great importance. According to 

 this theory the older the genus or the species, the more widely 

 distri])uted in area are its members, conditions being suitable. 

 In general, also, the older the genus the greater are the num- 

 ber of its species. According to this view, Persoonia juniperina 

 should be one of the oldest species of the genus in the Eastern 

 States. 



The study of the distribution of our plants, therefore, not 

 only offers an interesting field of investigation for local pur- 

 poses, and one the fringe of which has l)een barely touched, 

 but it may also help in deciding the value to be attached to the 



