206 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



Botanical Regions 



Those who have written on the phytogeography of the Gala- 

 pagos Islands in the past, have often mentioned the great 

 difference in the character of the vegetation on the higher and 

 lower parts of many of the islands, a difference that is very 

 marked and can often be readily seen at a mere glance from 

 the shore or a few miles out at sea by the contrast in the color 

 of the vegetation in the several regions. In fact it is often 

 easier to make out the limits of the regions from a distance 

 than close at hand, for they frequently grade imperceptibly 

 into each other, and the variations in color can not be so readily 

 distinguished when one is going through the islands. On 

 certain islands some of the regions are often ill defined or 

 entirely lacking, a fact that is probably due mostly to climatic 

 but sometimes to edaphic factors. 



Above the strand vegetation, which forms a narrow belt 

 along the shores in many places, four botanical regions can 

 be recognized, the Dry, Transition, Moist, and Grassy. 



Dry Region 



The lower slopes of the higher islands and the whole slopes 

 of the lower ones are covered with a vegetation which is very 

 xerophytic in character. The most striking plants in this 

 region are the arborescent cacti, which often occur in large 

 numbers and sometimes attain a height of forty or more feet. 

 Except the cacti, the trees in this region are for the most part 

 rather low, deciduous in character, and very much scattered. 

 Between the trees, where they occur, the ground is usually 

 covered with low bushes, which either shed or greatly reduce 

 their leaves during the greater part of the year, and those 

 which retain their leaves usually have them covered with a 

 heavy coating of plant hairs. The landscape accordingly pre- 

 sents a dreary gray aspect, which is greatly accentuated by 

 the color of the trunks of both the Croton bushes and Bursei-a 

 trees. 



During the spring months this region takes on a green 

 appearance, but is lighter in color than the moist region above. 

 During this season most of the annual plants spring up rapidly, 

 and mature before the dry season sets in again. 



