48 BOTANICAL RESULTS OF THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 



south-east trade wind, is covered with grassland. This position of the island, in the 

 direct track of the dry south-east trade winds, is responsible for the extremely small 

 rainfall, which at Georgetown (sea-level) averages under 3 inches a year ; but on 

 Green Mountain, at a height of 2000 feet, where the clouds often envelop the hill, it is 

 over 17 inches. With this very scanty rainfall the extreme desert nature of the plains 

 is little to be wondered at, and it was only at " Wideawake Camp," the nesting-place 

 of myriads of terns (Sterna fuliginosa), that much vegetation was found, which was 

 almost entirely composed of Portulaca oleracea, considered to be indigenous, and the 

 widely spread tropical grass Setaria verticillata, a species doubtless introduced by the 

 action of the terns. 



" Wideawake " is a hollow apparently slightly less arid than its surroundings, while, 

 in addition, the guano of so many birds must materially assist the vegetation. Portulaca 

 oleracea in places forms an almost continuous carpet, and is apparently well adapted 

 to the prevailing conditions, for without doubt it is spreading on the island. Of the 

 four phanerogams recorded from the island, considered by Mr Hemsley to be indigenous, 

 I found, besides Portulaca oleracea, only Euphorbia origanoides. This endemic species 

 is comparatively rare : near Georgetown on the " golf links " are a few stunted 

 specimens, though on the " road " across the plains to Green Mountain I found not a 

 few vigorous plants of it, all growing in an almost desiccated soil. Neither of the two 

 above essentially xerophilous species finds a place in the vegetation of the higher slopes 

 of Green Mountain. Several introduced weeds show signs of prospering, despite the 

 adverse conditions ; but the planted palms are all in an extremely miserable condition. 

 Among the species which seem to find themselves most at home are Vinca rosea, 

 Clematis, several species of Phy sails and Ricinus communis ; while several plants of 

 Opuntia, planted, I believe to give some shade near the "God be thanked" water-tank 

 on the road to Green Mountain, show every sign of spreading. In view of the 

 essentially desert character of these plains, it is surprising to find the statement of 

 Schimper 1 that " the island is almost completely overgrown with ferns," but this is a 

 deduction evidently drawn from the floral statistics, which show among indigenous 

 species a great preponderance of ferns. 



Encircling Green Mountain, at a height of 2000 feet, runs Elliott's Pass a pathway 

 some two to three miles in length and generally cut on the slope of the hill, but often 

 running through short tunnels where a precipice would otherwise interrupt its course. 

 On this path, and principally in the damper localities in or about the shaded entrances 

 to the tunnels, I collected all the cryptogams enumerated in the following list. The 

 list contains a few new records for Ascension ; and while, in the extremely altered 

 state of the vegetation to-day, it is impossible to assert absolutely that any of these 

 are indigenous, there is, on the other hand, no very plausible reason for considering any 

 of them as introduced. 



My collections suggest no new affinities for the flora of Ascension, which shows all 



1 Pjlanzmgeographie, A. F. W. Schimper (1908), p. 90. 



