no 



'i'hough the main communities on Pearson Island are at present in an active 

 state, the ultimate fate of the islands will be a bare granite reef if the present 

 cycle of denudation continues. Middle and Southern Pearsons show no community 

 higher than Olcaria-Lcucopogon thicket. 'Fhe outlying islands appeared to have 

 few, if anv, bushes upon tliem. The rate of degeneration upon Northern 

 Pearson, however, will remain slow, provided the flora is protected from 

 malicious fires. 



flora. 



■ A complete list of the vascular plants collected is given in Appendix II. 

 It comprises 52 species, though, as the islands were visited in the dry season, the 

 list is probably incomplete as far as herbaceous plants are concerned. The 

 most important families are: Chenopodiaceae (10 species), Compositae (9 

 species), and Gramineae (5 species). 



No member of the Leguminoseae was found on the islands. None were 

 found in the flora of Franklin Island. ^^^ Considering that the Leguminoseae 

 is the family represented by the greatest number of species in the Australian 

 Flora, ^'*^ its apparent absence is remarkable. 



The Myrtaceae are represented by three species, but no Eucalypt is present. 

 This, again, is a surprising feature, for mallee Eucalypts occur on the coast 

 of the neighbouring mainland. 



The Centrolepis appears to be new, but it was obtained with fruits only. 

 An attempt is being made to raise it from seed, and. if successful, the plant will 

 be described later by Mr. J. M. Black. 



In the list given below the growth forms according to Raunkaier's system 

 are also stated. There are three species of low trees (Microphanaerophytes, 

 5-7 per cent.) and 19 species of shrubs (Nanophanaerophytes 36 per cent.), 

 making altogether a phanaerophyte flora of 41-7 per cent, lliis is very nearly 

 the phanaerophyte percentage for the normal spectrum (43 per cent.), but there 

 are no other trees than microphanaerophytes and there is an overwhelming 

 preponderance of shrubs. 





Total number 











District. 



of Species 



Percentage of Species 



belonging 



to each Life Form. 





considered. 



MM. M. N. Ch. 



H. G. 



HH. Th. 



E. S. 



Pearson Island . . 



53 



— 57 36 28-3 



1-9 — 



— 282 



— — 



Franklin Island . . 



34* 



— — 15 38 



— — 



— 47 



— — 



Ooldea 



188 



•5 19 23 14 



4 -5 



— 35 



4t - 



Natal 



3,034 



3 14 14 19 



18 18 



5-5 6-5 



1 1 



Normal Spectrum 400 6 17 20 9 27 3 1 13 3 1 



The number of dwarf shrubs or herbaceous perennials is 15. These have 

 no special protection for their buds, but are mat plants, cushion plants, or grow in 

 tussocks (Chamaephytes 282 per cent. ) . The percentage is more than three times 

 that of the normal spectrum. On the Franklin Islands the percentage was even 

 higher. This may partly be attributed to the rather special habitat in wind- 

 swept islands, but there may be other reasons. When examining the arid type 

 of flora at Ooldea, Adamson and the writer '^"^ found a rather high percentage 



*The total number of species is so small that the percentages may be misleading unless 

 taken in a general way as emphasising the abundance of chamaephytes and therophytes and 

 the ai)scnce of most of the other life forms. 



t The epiphytes here were hemiparasites, very prominent in arid districts of South Aus- 

 tralia, for which no provision is made by Raunkaier's system. 



t^) Osborn, T. G. B., he. cit., p. 204, 1922. 



(■" Maiden, J. H., Australian Vegetation, Federal Handbook on Australia, p. 166, 1914. 



0«) Adamson, R. S., and Osborn, T. G. B., On the Ecology of the Ooldea District. Trans. 

 Roy. Soc. S. Austr., xlvi., p. 558, 1922. 



