76 PLANT HABITS AND HABITATS IN THE 



been formed. The species has a heavy root-crown and a thickened 

 stem-base, from which numerous branches arise. The entire aspect 

 of the species is shrub-like, with the "canopy" top so common among 

 AustraUan shrubs and trees. 



Isolated Species and Mixed Communities. 



Should the vegetation of the Copley region be studied from the 

 standpoint of its distribution, it would be found that all gradations 

 exist between the mono-specific communities above sketched and 

 geographically isolated individuals. As a matter of fact, possibly 

 most of the species occur mingled in this manner. Whether such small 

 communities or isolated individuals represent recent introductions 

 or survivals from populous mixed communities are matters of interest, 

 but this study throws no light on the problem. It is evident that the 

 controlling factor of the hill-slope flora is the single one of moisture 

 and that it is apparently a fortuitous mingling of mostly unrelated 

 elements. This is in sharp contrast to the flora of many species of the 

 Copley plain, which is bound by edaphic ties. In other words, the 

 conditions noted are the usual ones controlling the plant distribution 

 in an arid or semi-arid region. 



It is not especially unusual to find a single species of woody perennials 

 represented in any area by one specimen only. For example, one or 

 two specimens only of Hakea leucoptera occur on the top of Table 

 Mountain (plate 11 a), although there is a small colony of about 20 

 widely separated individuals on low slopes at the head of a draw at 

 the east base of Mount Deception Range west of Copley. It was not 

 seen apart from these two situations. At Copley the species has the 

 habit of a small tree, about 5 meters high, with a pronounced canopy- 

 shaped crown. The leaves are needle-like (plate 12d) and the whole 

 appearance of the species is as one well adjusted to very arid condi- 

 tions. It is one of the species which has probably suffered little by 

 the advent of the white man and his varied activities. It is not eaten 

 by his animals or used by him as a fuel. For these reasons the oc- 

 currence of the species as to its distribution in the Copley region 

 probably represents its reaction to the physical environment only. 

 Such a remark might also be made regarding smaller woody peren- 

 nials, as the Eremophilas and Cassias. 



Another woody perennial which occurs sparingly is Petalostylis 

 labicheoides. This species was found at the south and west base of 

 Table Mountain, in a straggling group or two of few individuals. It 

 was seen in no other place. The shrub has a very striking appearance, 

 but imperfectly shown in plate 12, a and c. Several branches of ap- 

 proximately equal length are fairly well clothed with compound leaves 

 which carry 15 to 31 leaflets. Thus the leaf-area is large, although the 

 leaflets are rather small. 



