322 . A. A. HAMILTON. 



exudation is greatly increased, a sticky stain is left if the 

 leaves are drawn through the hand. Its congener L. con- 

 cavum R. Br., has thinner and more flexible leaves and 

 stems. The dioecious Restio dimorphus R. Br., a coastal 

 sandstone species common in the Port Jackson district, 

 spreads a drooping plume-like tuft whose density presents 

 an effective barrier to intruders. 



Panicum marginatum R. Br., a wiry-stemmed straggler, 

 reduces the density of its tuft under drought conditions by 

 restricting the number of its stems, and narrowing and 

 recurving the margins of its leaves. Discussing the varie. 

 ties of this species, Bentham, (Fl. Austr., vii, 486) says of 

 P. strictum R. Br. — which he has reduced to a var. of P. 

 marginatum — "Some specimens seem to show that the P. 

 strictum is rather an aftergrowth from plants that have 

 been cut down than a distinct variety." In one of the 

 swamps in the Centennial Park there is a dense growth of 

 this form which under normal conditions has the flattened 

 habit of the typical P. marginatum, but after a fire has run 

 through the swamp the young shoots are upright and 

 luxuriant, exhibiting a striking contrast to the older growths 

 which have escaped the fire. The swamp form is more 

 compact than the rock-dweller, and does not attain either 

 the elongated paniculate inflorescence or the breadth of 

 leaf of the typical P. marginatum. 



Descending from the headland to Freshwater Beach, 

 Rottbcellia compressa L.f., a climatically adaptable species 

 which has reached Australia from India via the Malayan 

 Archipelago and proceeded south to Tasmania, was noted 

 lining the moist rock benches at the base of the escarpment, 

 flanked by small communities of Lobelia anceps and Samolus 

 repens. The association under similar conditions of this 

 series of swamp habitues was frequently observed. The 

 vegetation on the dune at Freshwater Beach has been 



