THE VEGETATION OF THE JUAN FERNANDEZ ISLANDS 925 



56. (14 D.) Dendroscris ///r-'w/Av-Sociation. Morro del Spartan, 26/1 19 17. 

 Dry, sandy and naked soil. 



II: 3 Matthiola incana 



Dcmh-oscris litoralis 1-2 \\^^xu^x crispus 



Rca pruinata I " P^'c'^e"" 



Solamiin 7-obinsoiuanuiii i 



11: - Sonchus oleraceus 



Avena barbata abundant Wahlcnbergia Berteroi i 



II: I 



Centaurea melitensis 



Chenopodium murale 



Chawpodium Sanctae Clarac I Amblyopappiis pusillus 



Erigeron canadensis Spergularia confertiflora i 



Gnaphalium cheiranthifolium Tetragonia cxpatisa i 



Hordeum muriniim 



The hard basalt dykes are covered with lichens. 



Acnrospora xaiitliophaiia Microglaena ferfwndezimta 



Blastenia fernandesiana Pai/iie/ia cctvdta 

 Buellia concinmx var. » conspcrsa var. 



» stelliilata Pertusiuia melanospora cop. 

 Caloplaca elcgans v. austmlis » Skottsbergii 



» rubina cop. 



The Plant Communities of Masafuera. 



Remarks on the Topogkaphv. 



Masafuera rises abruptly out of the depths of the ocean, a solid, approx- 

 imately rectangular block, tilted NE and with the longer axis directed N — S, an 

 elevated tableland bordered by very steep to almost vertical, shore-bounded 

 escarpments, which along the west side rise to over lOOO m, culminating in 

 Los Inocentes and Cordon Atravesado. The coast cliffs on the east side are 

 much lower, but just as steep. The longitudinal ridge follows the western border 

 of the block and is very frequently hidden in thick fog; precipitation is high 

 and the west barranca furrowed by hanging ravines, where a cascade tumbles 

 down after every downpour. On the east side the ridge is bordered by the nar- 

 row Piano de la Mona, where the streams which have eroded the deep valleys 

 opening on the east coast have their sources. As the south half of the island 

 is considerably higher than the northern half, rising to about 1500 m, precip- 

 itation is much heavier here and the eroding forces very powerful; this is where 

 we find a magnificent series of canyons, narrow chasms many hundred metres 

 deep, with vertical walls. The largest two, the Casas and Vacas quebradas, have 

 been cut back almost right through the island; it is just possible to find a passage 

 round the origin of the Casas valley, whereas the knife-edge crest forming the 

 back wall of Vacas is impassable. Between the two valleys lies Cordon del Bar- 

 ril, broad and gently sloping toward the sea in its lower part, upwards narrowing 

 to a thin ridge with an abyss to 900 m deep on either side. The table-land 



