306 A. A. HAMILTON. 



The broad benches of the rocky escarpment are thinly 

 coated with a layer of soil, (Narrabeen Shale) eroded from 

 the embankment above, on which two grasses, Imperata 

 arundinacea Oyr., "Blady-grass," and Themeda Forskalii 

 Hack. var. imberbis, "Kangaroo-grass," have established 

 colonies. Both species form gregarious communities, the 

 former linking up its members by their subterranean stems, 

 and the latter binding its closely packed tufts by interlac- 

 ing their serial stems. Though the communal bond is a 

 palpably useful device in this unstable environment, it does 

 not appear that these plants have adopted it with a view 

 to the conquest of this territory, as both species act in a 

 similar manner in situations where the soil is perfectly 

 stable, though in the latter case the tufts of the "Kangaroo- 

 grass" adopt a more open formation. It is evident that the 

 survival of these grasses, in this exposed position, is due to 

 the suitability to the prevailing conditions of their ordinary 

 habits and structure. A few clumps of the cosmopolitan 

 J uncus effusus L., are present in the moist rock crevices. 

 It does not favour the dry dune slopes, its massed formation 

 on the margin of the beach lagoon disclosing its preferential 

 habitat. The taller species of Juncus, (3 unci genuini) are 

 exceptionally plastic, and owing to the paucity of fixed 

 morphological characters are difficult to separate. 



At the extremity of the promontory, the steep bluff, and 

 the easily eroded shale of which it is composed, have, in 

 combination, created a situation so detrimental to plant 

 life that the slope is almost bare. Two trailers, Kennedya 

 rubicunda Vent., and Wedelia biftora DO., are the only 

 inhabitants of this inhospitable region. The former extends 

 to the coastal tableland but the latter is confined almost 

 exclusively to the shoreline. Its habit of scrambling among 

 hedges and rocks near the sea side, is noted by Bentham in 

 the "Flora Hongkongensis," p. 163. Beyond the point the 



