62 
Th e South Australian Natural ist. 
2. A Rush Formation. 
This ^formation is dominated by a rush, Heleocharis acuta 
(No. 2215) plants of which are growing so densely together as 
to become a closed formation. The plants are about one foot 
m height and form a thick mat over the soil. Sparsely distribut- 
ed are Cyperus vaginatus (No. 2216) which is found chiefly on 
the division of this and the previous formation, the bul-rush 
{Typha augustifolia) (No. 2217) with Ce?itipeda (No. 2218) a 
clover, Trifolium jragiferum (No. 2217a) with pink woolly heads 
and a grass {Polypogon monspeliensis , No. 2219). This formation 
is about 3 inches lower than the samphire zone and is about 30 
yards in width. 
• _ Rush - Mimulus Association. 
This association consists chiefly of the rush, Heleocharis acuta 
and of Mimulus repens (No. 2221). The former is in tussocks 
scattered about^ and the latter covers almost all the remaining 
surface. Occasional plants of Alternanthera triandra (No. 2222), 
a dock, Rumex (No. 2220), Typha, and Cotula coronopifolia (No! 
2223) are seen. The small Triglochin striata is much more plentiful. 
This is lower ground than the previous formation and shells oc- 
cur here, as in all the lower ground, in great numbers. 
4. Scirpus - j uncus Association. 
Going still further toward the main stream island-formations 
occur with Scirpus americantis (No. 2224) In dense patches. This 
species dominates small areas but has Triglochin striata and Mim- 
uhis^ repens, etc., occurring with it. Juncus polyanthemus (No. 
2225) occurs here forming tussocks with the Scirp^is. Neither of 
these dominants mix but they occur as small closed formations. 
Where the ground is a little higher other plants occur such as 
Cyperus vagmatuSy Cynodon dactylon and Gnaphalmm japoni- 
cum, 
5. Crassula - Triglochin Association. 
In the last areas to become dry two small plants combine to 
dominate the area. Crassula recurva (No. 2221) is most abun- 
dant and forms a mat over the ground, this plant is moisture 
loving and Its stems and leaves retain their moisture for a long 
while. The Triglochin striata again is plentiful but does not oc- 
cur as thickly as its associate. Mimtdus repens also grows well 
here and a few plants of a large Triglochin {T. procera) and 
Heleocharis acuta. 
6. Scirpus lacuster Formation. 
In a very' wet situation the tall rush Scirpus lacuster (No. 
2226) grows very luxuriantly, the plants being from 4 to 6 feet 
In height. So closely packed are the stems that they make a 
closed formation. However a few specimens of the bul-rush 
are seen among it and it Is able to survive in ‘his situation be- 
cause it also Is a tall plant. 
