592 



both grew on the fiats with Casual ma, Grcvilha /lueijtlii, 

 and Acacia colletioides. Erenwphila scoi)arki was associated 

 with CarSaia ertmo'phila and C . Sturtii, and, in places, formed 

 quite a distinct feature of the vegetation. Thrifpfornent 

 EUiottii was seen on a sand ridge at Barton. 



In a photograph (pi. xli., fig. 2) taken at Barton 

 Thryptomene EUiottii is, seen in the foreground with 

 Gasuarinu lepidophloia Skiid Eucah/j)^ ns close by. In another 

 situation, Casuarina lepidoijhloia is growing with acacias, 

 mallee, and Triodia irr/tan'S. This latter plant was fairly 

 common at Barton, and, in another place, it was noticed 

 associated with Solanurn coactdlferum^ Acacia ligidata, and 

 Thryptomene EUiottii. The common "parakeelya" (Calaic- 

 drinia polyandra) of the sandhills was growing so profusely 

 in places that it became almost a closed formation, its asso- 

 ciates in one place were HeUchrysiim lucidiim and ^olarcuin 

 orhictdatum. In open, flat ground Trichinium corymhosum 

 and Podolepis capiUaris were associated ; they are both small 

 annuals. 



V. Desert Formations of the Tar cool a Region. 



CLIMATIC AND EDAPHIC FACTORS. 



The sandhill region is left at Wynbring, where, travel- 

 ling east, an undulating stony country is entered upon. As 

 was to be expected, the flora changed as soon as the sand- 

 hills were left behind. The vegetation now was not so dense 

 or plentiful, no doubt caused by the dry subsoil. The top 

 soil is of a clayey nature in this region and surface water 

 would remain longer than in the sandhills. In the sandy 

 country more moisture reaches the subsoil, which proves to 

 be of a wonderfully retentive nature; there is, consequently, 

 a greater amount of moisture available for the plant cover- 

 ing. This influences the flora of the two regions under 

 discussion. 



KOCKIAS AND ACACIAS OF TARCOOLA. 



The predominating species in this station is Kochia 

 sedi folia and Acacia Loderi, while Kochia triptera and 

 Eremojyhila rotiindifolia are represented by numerous plants. 

 Also Acacia aneura claims attention, as it was frequently seen ; 

 Hakea leucoptera was not so plentiful. The plants on top of 

 a rocky hill (pi. xlii., fig. 1) consisted of Acacia tarciden.^is 

 and Trichinium itvcanum, which were the dominants; here 

 and there Rhagodia (TaudichaudiarM and Enchylaena 

 iomentosa were seen, while the smaller plants, Helipterum 

 Fitzgibhonii and //. pterochaetum were fairly numerous. < The 

 rocky slopes of the low hills have a distinctive fiora, and, 

 besides the prevailing bluebush, Helipterum, Hinnholdfianum, 



