50 A NATURALIST IN THE PACIFIC CH. vi 



from 2,000 to 2,400 feet above the sea. It is also evident from 

 Mr. Cheeseman's memoir on the Rarotongan flora that coast plants 

 also stray inland in that island. In an island like Raro tonga, where 

 a sorry substitute for a mangrove-swamp exists in the form of a few 

 coastal muddy places occupied by Vitex trifolia and Sesuvium 

 Portulacastrum, Entada scandens takes to the hills ; and thus it is 

 that in this island it is most abundant in the interior, climbing to 

 the tops of the highest trees and " covering acres of the forest with 

 a dense canopy of green." 



Summary of the Chapter. 



(1) The Tahitian region possesses most of the plants that 

 frequent the sandy beaches of the Pacific islands. 



(2) But it lacks the mangroves and the associated plants of the 

 mangrove-swamp. 



(3) It also wants many of the plants that grow in the vicinity of 

 such swamps. 



(4) But since the plants last-mentioned often possess 

 fruits or seeds capable of being carried great distances by the 

 currents, their absence is to be attributed to the necessary 

 conditions being lacking on account of the failure of the 

 mangroves. 



(5) Most of the beach plants, however, owe their existence in 

 this region to the transport of their buoyant fruits or seeds by 

 the currents. 



(6) The negative features of the Tahitian strand-flora are 

 mostly to be connected with the absence of Rhizophora and 

 Bruguiera, the pioneers of the mangrove-swamp ; and their absence 

 is, in turn, to be attributed to the inability of their floating 

 seedlings to reach this region in a fit condition for establishing 

 themselves. 



