VEGETATION OF BLAKEXEY POINT. 
515 
numerous scattered plants of Obione portulacoides, which, 
however, is prostrate in habit, seldom attaining more than two 
or three inches in height or a foot in diameter. To these 
species must be added Armeria rnaritima and stunted 
plants of Glyceria rnaritima and Plantago Coronopus, the 
latter usually with almost glabrous and but slightly toothed 
leaves. 12 
(4.) The Crest. (Fig. 13). 
The fourth zone forms the larger part of the bank, and is a 
grassy sward of numerous species in which the dominant 
plants are Armeria rnaritima, Silene rnaritima and Agrostis 
rnaritima. 
Common in this zone also are Sed'um acre , Arenaria 
serpyllifolia and Plantago Coronopus ; the first two are 
usually associated together, and the last frequently with 
Cladonia rangiferina, especially towards the base of the 
banks. Trifolium arvense, Trifolium striatum, Cerastium 
tetrandrum, Sagina rnaritima, and Lepturus filiformis, have 
a distribution which coincides roughly with the tracks, formed 
by the coastguards and others, which usually pass along the 
main axes of the banks. This habitat is probably to be inter- 
preted as due to the low growth and barer character of 
these places, rather than to direct human agency in their 
distribution. Such a view seems to be borne out by the fact 
that some of these species are most abundant on banks where 
the amount of traffic is not greatest. In the case of Lepturus 
filiformis, there is a decrease in amount as we pass from 
the older to the younger laterals, till on bank No. 8, which is 
probably visited more than any other on account of the Watch- 
house, the species is entirely absent. The mode of occurrence 
of several of these plants in other localities and formations is 
also in accordance with the view here expressed. 
Owing to the exceptional character of bank No. 5, mentioned 
above, the whole of its flat top is occupied by the Binervosa 
association, and the crest plants themselves are altogether 
12 On Bank No. 8. and there only, we find in this association in one place 
plants of Spergularia salina. 
