Stewart — Botanical Conditi&tis pn the Galapagos Islands. 275 



growing in this region, less abundantly than the above are : Cor- 

 dia lutea, Castela galapageia, Croton Scouleri var, brevifolius, 

 Euphorbia artieulata, Prosopis dulcis, Sealesia Hopkinsii, Tel- 

 anthera eehinocephala, and Waltheria reticulata. The lava 

 ridges are often found to be more or less covered with vines 

 of Ipomoea Habeliana, and in various other places on the 

 lava, I. Kinbergi was found growing and in blossom at the time 

 of our visit. Such grasses as Aristida suspicata. Cenchrus platy- 

 acanthus, Leptochloa albemarlensis and L. Lindleyana grew 

 with more or less abundance in the lava crevices. On the older 

 beds of volcanic cinders there was very little vegetation other 

 than occasional bunches of Cereus nesioticus ; the more recent 

 beds of cinders were bare. 



A change, readily noticed, takes place in the vegetation at 

 about 450 ft. elevation evidently brought about by the greater 

 amount of moisture and a more abundant soil. There is a gen- 

 eral thickening up and an increase in the size of the vegetation 

 above this elevation. There are good sized trees of Bursera 

 graveolens in this region, and also trees of Pisonia floribunda, 

 which first make their appearance. Many of the trees and 

 bushes, at this elevation and above, are heavily covered with 

 Aleetoria sarmentosa and other epiphytic lichens. Bushes and 

 small trees of Zanthoxylum Fagara also occur, usually infested 

 with Phoradendron Henslovii. Other bushes which occur in this 

 region and a little higher are : Chiococca alba, Erigeron tenui- 

 folius, Lipochaeta laricifolia, and Lippia rosmarinifolia. Such 

 ferns as Chelianthes mierophylla, and Polypodium squamatum 

 occur. Very little change takes i)lace in the vegetation on the 

 southwest side of the island below an elevation of 700 ft., prob- 

 ably due to the fact that this side receives less moisture than the 

 south and southeast sides. 



Practically all of the plants which occur below 500 ft. dis- 

 appear by the time an elevation of 1,000 ft. is reached. The spe- 

 cies that continue into this region from below, are, for the most 

 part, those which first appeared around an elevation of 500 ft. 

 and above. The region between 1,000 and 1,650 ft. elevation is 

 covered with forests, on the southeast side, which are made up 

 mostly of Pisonia floribunda, and Zanthoxylum Fagara. There 

 is much undergrowth in these forests, consisting of bushes of 

 Croton Scouleri var. grandifolius, Erigeron tenuifolius, Lippia 

 rosmarinifolia, Psychotria rufipes, Sealesia HopMnsii, Toume- 



