CHAPTER X 

 CACTUSES AND OTHER SUCCULENTS 



The name succulent is applied to plants with fleshy leaves or 

 stems. If they are to be cultivated in a rational manner, it 

 must first be understood how they came to acquire this 

 character. They belong to many distinct genera, and are 

 natives of many widely separated countries, mostly tropical ; 

 but in almost all cases they grow among rocks or in sandy 

 deserts, where there is no shade from the heat of the sun and 

 where, for the greater part of the year, there is no rainfall, 

 and then perhaps for a short time an excessively heavy one. 

 Obviously, no plants could exist under such conditions unless 

 they were able to store some of the infrequent surplus and, 

 like the camel in the animal kingdom, make use of it during 

 the long periods of drought — make use of it, too, with the 

 greatest economy. This is just what succulents can do. The 

 cactuses will serve as an illustration. As the result of the 

 long droughts to which they have been exposed for countless 

 generations, their leaves have gradually dwindled away until 

 now they are merely spines, and their functions have been 

 taken over by the green stems, swollen by the absorption of 

 much water during the periodical downpours, and able to part 

 with their store only very slowly afterwards because of the 

 comparative fewness of their stomata or pores and the thick- 

 ness of their integument. In other genera which are exposed 

 to less severe drought, the leaves, instead of dwindling, have 

 become swollen, the thickening of the integument in their 

 case also lessening the rate at which the water stored in them 

 can escape. 



Some of the succulents are natives of Britain ; for instance, 



