ARID PORTIONS OF SOUTH AUSTRALIA. 117 



NOTES ON SOME STRUCTURAL FEATURES OF PERENNIALS. 



Although the material at hand was not primaiily collected or pre- 

 pared for anatomical study, i1 was found that by proper handling and 

 treatment it yielded much better results from this point of view than 

 was at first expected, probably because so large a proportion of the 

 tissues of the leaves or phyllodia is composed of mechanical tissue 

 of whatever sort. The following sketch of some of the most striking 

 features of the anatomy of the chlorophyll-bearing organs of represent- 

 ative perennials is based, so far as the original observations are con- 

 cernied, wholly on the study of such herbarium material. 



In this brief survey of the anatomy of the species the observations 

 have been almost wholly confined to such tissues as are most directly 

 concerned with the water relations of the plants. Scant reference 

 has been accorded any other features. No attempts, therefore, have 

 been made looking to thorough or exhaustive treatment, much as 

 that is desirable, inasmuch as the subject of structure should and un- 

 doubtedly will receive adequate attention from others who will study 

 living material, which was not practicable in the present instance. 

 Observations were made on the following species: 



Acacia aneura. Eremophila alternifolia. Fholidia scoparia. 



continua. brownii. Fusanus acuminatus. 



linophylla. latrobei. Gravillea stenobotrya. 



tarculiensis. longifolia. Hakea leucoptera. 



tetragonophylla. neglecta. multilineata. 



Bossiaea walkeri. oppositifolia. Melaleuca parviflora. 



Casuarina stricta. paisleyi. Pittosporum phillyrseoides. 



Dodonsea attenuata. rotimdifolia. Triodia irritans. 

 lobulata. 



THE PHYLLODIA IN SOME SPECIES OF ACACIA. 



All species of Acacia which were studied in the field either bear 

 phyllodia in the place of leaves or are aphyllous. Such organs show 

 most clearly the impress of the subaerial environment. Naturally 

 the response takes place along a variety of lines, but in a region of 

 great aridity it has much to do with the water relation. This is re- 

 vealed in devices of various kinds which lead to a conservation of 

 water, but it is also shown in the relatively great formation of cell- 

 walls, a direct result, as already pointed out, of a small water-supply. 

 All of these features are shown well in various species of the genus 

 Acacia, the leading characteristics of the structure of which are known. 

 I shall point out, in the present paper, some of the most striking 

 features in the structure of a few species which were found in the 

 desertic-arid portions of South Australia and certain of which may 

 not be generally known. Of the species A. aneura, continua, lino- 

 phylla, tarculiensis, and tetragonophylla, all except A. continua and A. 

 tarculiensis were found at Oodnadatta; A. continua was studied at 

 Quom, and A. tarculiensis was seen at Tarcoola, its type habitat. 



