553 



prominent; indeed, one or both of these two are often the only- 

 plants present. The other species present are Dodonaea 

 attenuata, Acacia Ugulata, Cassia eremo'phila, with locally 

 Hihhertia cris'pula and Adriana fonitntosa^ the lastnamed in 

 hollows. On the bare sand there were occasional plants of 

 Sahola kali, Myriocephalus Stucirtii, and a few tufts of Stijya, 

 sp. These scattered tufts appeared dead and were much eaten 

 down by rabbits. 



In the Soak the water-table is about 5 ft. to 15 ft. below 

 the surface, but yet this seems to have very little effect on the 

 plants. Adriana tomeMosa, and possibly Melaleuca, are the 

 only species that seem dependent on the presence of ground 

 water. Adriana, which is known as the "water bush," has 

 a leaf very different from any other plant found in the district. 

 It is relatively thin and spreading horizontally, neither at all 

 succulent nor hard and coriaceous. The leaves and shoots of 

 this plant have a much vsmaller water content than most of the 

 other plants found. 



LeptosjK:rmum, which is such a feature of the sandhills 

 in the basin, also occurs on many of the sandhill ridges in 

 230sitions quite remote from supplies of bottom water, and it 

 eeems better regarded as a plant characteristic of loose sand- 

 than of moisture. 



Salt Lake. — Separated from the Soak by a high ridge of 

 sand with the typical vegetation of Acacias, etc., is another 

 basin occupied by a small salt lake (pi. xxxvi., fig. 1). At 

 the time of our visit this lake was dry, and the loose level soil 

 of the bed was largely composed of soluble crystals, amongst 

 which gypsum crystals were numerous. 



The main bed of this lake was bare of plants, but round 

 the margins occurred a halophytic vegetation. Tliat nearest 

 to the bed was an open community of Arthrocnemum, spp. 

 (A. halocnemoides, A. halocnemnides, var. 'pergranvlatwm, 

 and Arthrocnemum, sp.). At a slightly higher level occurred 

 Frankenia fruticidosa, often almost pure or mixed with a few 

 plants of A triplex paludcsuni, Bassia diacantha, Kochia hrevi- 

 iolia, Mesemhrijanihemtnn aequilaterale, Xitraria ScJweberi, 

 while still higher on the sand just below the typical bushes of 

 the surrounding sandhill flora occurred SalsoJa kaJi^ Afriplex 

 vesicaria, Stijm, sp. (dead tufts), Calandrinia voJvhiUs, and 

 Didiscus cyan-opetal us. Beyond this zone one passed into the 

 typical sandhill flora (pi. xxxvi., fig. 2). 



RELATIONSHIPS OF VEGETATION.^ 



The salt lake just described was interesting, especi- 

 ally as demonstrating the total change of flora that 



