SUCCULENT PLANTS. 



455 



parts of the world. One other plant only need be mentioned, and that 

 is Kleinia neriifolia, a shrub of upright-branching habit, with thick 

 stems and narrow leaves, worth growing with other plants of the Canaries. 



We now cross the Atlantic, and here, on the American continent, we 

 find practically all the Cactaceae, only a few unimportant species of 

 Rhipsalis being found in Madagascar and Africa. They grow from 

 Manitoba, in Canada, where Mamillaria vivipara is found, down to 

 temperate Chile, with their chief centre, no doubt, in Mexico, where 

 several genera of supreme interest are found. They usually consist 



of a thick fleshy stem, ranging in height from one or two inches in 

 the smaller Mamillarias to sixty feet in Ccrcus gigantcus. They are 

 usually leafless, but have a special development of spines : true leaves 

 are found in Opuntia, but of ordinary flat type only in Pcrcshia. In 

 this genus, too, the flowers are sometimes stalked, but almost always 

 the flowers of cacti are sessile. They are often very brilliantly coloured, 

 the tints being clear and transparent. Until we come to Rhipsalis, all 

 genera have a calyx tube above the ovary. 



Melocactus. — The first genus to which I shall call your attention 

 is Melocactus. Schumann counts fourteen species, but one only is 

 commonly seen in cultivation. This is M. communis, the first cactus 

 ever seen in this country, having been introduced about the year 1581. 

 The stem is more or less globose, 1-5 feet in diameter, with from 



America. 



Fig. 73. — Mamillaria gracilis. 



