TRANSACTIONS OF SECTION K. 585 
lat. 34° 56’ S. and long. 138° 35’ E., being a portion of the eastern shore of Gulf 
St. Vincent. The annual rainfall is about 18 inches, the bulk of which falls in 
the winter months, April to September. The summer temperatures may be high, 
not infrequently over 100° F. in the shade. The prevailing winds during the 
summer are §.W. to S., in the winter N.E. to N. 
St. Vincent Gulf is of very recent origin, and since Pleistocene times the 
coast has undergone several submergences and uplifts. The sand forming the 
dunes has been heaped up along the shores of the gulf against the seaward 
extension of the recent and Tertiary clays forming the Adelaide Plain. These 
clays are exposed by the drifting sand in small patches at the S. of the area. 
The dunes raised by the action of the S. and S.W. winds have been prevented 
from attaining any great height by the action of the strong N. and E. winds 
which blow at certain times. In the shallow waters of the Gulf are large areas 
of Posidonia, Pectenella, and Zostera, the débris of which, cast up by the tide, 
form long banks a foot or more thick and as much as 20 feet across at high- 
tide mark. These banks protect the dunes as well as forming a basis for new 
ones. 
Vegetation.—In connection with the dunes the following communities? may 
be noted :— 
Strand Plants.—Atriplex cinerea, Salsola kali and *Cakile maritima.* 
Mobile Dunes.—These are colonised chiefly by Spinifex hirsutus, which has 
stout, creeping rhizomes. *Ammophila arenaria is planted in places, and 
is spontaneous on some mobile areas. The floor of a ‘ blow out’ is usually first 
colonised by Salsola kali. 
Static Dunes.—The greater part of the dune fringe may be described as 
static. Spinifex hirsutus frequently extends over the seaward face to the level 
of the strand flora. Associated with Spinifex and in part replacing it are many 
shrubs. Of these Olearia axillaris is the most important, but Secvola crassifolia, 
Alyzia buxifolia, &e., also occur, and are all able to grow through sand deposited 
on them. Other plants include Pelargonium australe, Lotus australis, 
*(@nothera biennis and Senecio lautus. : 
Fixed Dunes.—In addition to the plants mentioned above, and other shrubs, 
various Cyperaceous plants (Scirpus, Lepidosperma) and also Dianella occur. The 
radiating prostrate stems of Mesembryanthemum cequilaterale cover much 
ground and serve to bind the sand. Valleys of varying depth and width occur 
between the dunes. In the deeper ones shrubs are common, as above, with 
Leucopogon Richei, Myoporum serratum, The ground flora has many herbaceous 
plants and includes several aliens. The shrubby flora is not so characteristic 
of the more open valleys. These are colonised by Mesembryanthemum cequi- 
laterale and * Gnothera biennis. The dunes remote from the sea are occupied by 
an open community of shrubby plants in which Acacia salicina, Dodonea viscosa 
appear; Muehlenbeckia adpressa, Clematis microphylla are woody climbers. 
Trees of Hucalyptus odorata and Casuarina quadrivalvis occur, and there is 
evidence that they were formerly more abundant. 
Marine Salt-marshes.—These are developed on the landward side of the 
dunes in various estuarine areas. 
Mangrove.—The portions subject to tidal scour are colonised by Avicennia 
officinalis. On the shoreward margin this is mingled with Suda maritima. 
Salicornia Swamps.—Salicornia australe and S. arbuscula are the most im- 
portant plants over large areas subject to occasional tidal inundation. Brackish 
swamps beyond the tide-limit are characterised by Melaleuca pustulata with 
Salicornias and Frankenia levis, while Mesembryanthemum australe also grows 
on better-drained patches. These swamps may pass abruptly into sand-dunes 
or may show zoning, as (1) Salicornia; (2) Salicornia and Samolus repens; (3) 
Samolus repens and Sporobolus virginicus; (4) Sporobolus, Spergularia, &c., 
passing to dune flora. 
1 Howchin, A.A.A.S. Report 1913. 
2 The word ‘communities’ is used intentionally in preference to the term 
‘ association,’ which it is thought better to avoid in the present preliminary 
communication. } 
* Plants not recognised as native in South Australia are distinguished by 
* preceding the name. 
