491) ECOLOGICAL STUDY OF SALTMARSH VEGETATION. 



offers no obstruction to the shrubs which are driving it back as 

 they advance. This is one of the first weeds to appear on 

 newly-cleared land, especially in places where the previous vege- 

 tation has been destroyed by fire. It soon becomes exhausted 

 in a habitat and dies out, a phenomenon not infrequently noted 

 among herbaceous weeds. The fruits of the Poke-weed were 

 found in the stomachs of the following Australian birds (38) • 

 Peaceful Dove, Geopelia placida, Yellow-throated Scrub-Wren, 

 Sericornis barbara, Silver Eye, Zosterops coerulescens, Yellow 

 eared Honey-eater, Ptilotis chrusotis. 



Solatium auriculatum Ait., a tropical American herbaceous 

 perennial with several vernacular names each obtaining a more 

 or less wide acceptance, is represented by a few individuals 

 whose behaviour is somewhat similar to that of the Poke-weed, 

 though it is not so widespread. The Wild Cotton-plant Gompho- 

 carpus fruticosus R. Br., introduced from South Africa, which 

 has also secured a footing in the forest will be more difficult 

 to displace than the two preceding species, its tough fibrous 

 stems and compact formation presenting a formidable line of 

 defence. As it advances, the shrubby Melaleuca ericifolia is 

 overcoming the Gomphocarpus in the swamp but cannot follow 

 it on to the dry hillside. A coma of silky hairs is appended 

 to the seeds of the Gomphocarpus, but their attachment is weak 

 and they are of no value for flight. The seeds sink within a 

 few hours. 



In a C'asuarina forest at the head of the saltmarsh at Wooloo- 

 ware Bay (Cronulla), the Bramble, Rubus fruticosus L., has 

 established a thicket and initiated the invasion of a slightly 

 raised, comparatively dry flat, exterminating all except the ar- 

 boreal vegetation in its onward march. The Bramble is ad- 

 vancing in the direction of a colony of Melaleuca ericifolia 

 which has entered the flat from the swamp. When the two for- 

 mations come into contact, the Bramble, with its effective offen- 

 sive equipment, will dominate the Melaleuca. Its firm but supple 

 canes, furnished with broad horizontally-arranged leaves, will 

 run over the tops of the Melaleuca bushes, building a thick 

 screen and depriving them of light, its powerful rhizomes mean- 

 while forcing a passage among the shallow roots of its opponent, 

 competing with them for nutrition and sapping their vitality. 

 Attacked both above and below ground, the Melaleuca will be 

 compelled to retreat until the habitat becomes too moist for the 



