Stewart — Botanical Conditions on the Galapagos Islands. 283 



The lower slopes of the mountain are more heavily covered 

 with vegetation than is the plain just mentioned, but even here 

 there are often areas of a considerable size which have scarcely 

 any vegetation on them. The species which occur on the plain 

 also occur on the side of the mountain in greater number, and 

 many of them that were stunted on the lower part, reach their 

 noi-mal size around an elevation of 1,000 ft. The increase in the 

 humidity of the atmosphere is show^n at this elevation, and 

 above, by the large amount of Usnea longissima, and other lichens, 

 which cover the vegetation to such an extent as to give it a gray- 

 ish appearance. A number of mesophytic plants were first seen 

 around 1,300 ft. elevation, tho most noticeable of which were: 

 Pisonia floribnda, Psidium galapageium, and Scalesia micro- 

 cephala, the last of which forms a zone on this side of the moun- 

 tain to an elevation of 1,650 ft. There are also a great many 

 Bursera trees at an elevation of 1,200 ft. and above. Below this 

 they were few in number. Ferns begin to appear at a slightly 

 higher elevation. 



There is an abrupt change in the appearance of the vegetation 

 at an elevation of 2,000 ft. The character of the soil also 

 changes here from pumice to disintegrated lava mixed with vege- 

 table mold, so that the change in the vegetation is due more to an 

 increase in the number and size of plants than to a sudden 

 change of forms. There are heavy forests here made up of 

 trees of Bursera graveolens, Pisonia fioribunda, Psidium gala- 

 pageium, and Zanthoxylum Fagara as well as many species of 

 bushes the most of which were found at a lower elevation al- 

 though usually smaller in size. The trees are often covered wdth 

 vines of Cissampelos Pareira, and fruticose lichens continue to be 

 abundant. Ferns are also abundant, the common species being 

 Adianaum concinnum, Doryopteris pedata, Polypodium pectina- 

 tum, and Trachypteris pinnata. Small specimens of Opuntia 

 myriacantha were seen at this elevation and they continue to 

 within a few hundred feet of the top of the mountain according 

 to Mr. R. H. Beck, who visited this region. 



The sides of this mountain were not explored botanically above 

 an elevation of 2,100 ft. From the top of a tree at this elevation, 

 the whole of the country beyond could be seen. The character 

 of the vegetation did not seem to change until the steep slope, 

 below the rim of the crater is reached. Just below the rim, in 

 several places, there were light green areas which, according to 



