li CACTACEOUS PLAOTS. 



tube being prodaoed beyond the ovary, the stem being covered with 

 elongated tubercles or ribs, which are raiely leafy. This includes the 

 genera Melocactus, Mamillaria, Peleoyphora, Leuchtenbergia, Eohino- 

 cactus, Discocactus, Cereus, Phyllocactus, and Epiphyllum. The second 

 tribe, Opuntiso, has the calyx tube not produced beyond the ovary, and 

 the steins are branching or jointed. The genera Ehipsalis, jSTopalea, 

 Opuntia, and Pereskia are placed under this head. Some secondary 

 divisions are adopted, but they are not of much popular importance. 

 In classifying the species the spines afiord valuable characters, and those 

 who are specially interested in this part of the subject will find an 

 elaborate system detailed in Labouret's " Monographie." The genera 

 •which are reviewed in the following pages are taken in the order adopted 

 in Hooker and Bentbam's work already mentioned. 



MELOCACTUS, ZinJi and Otto. 

 (The Melon Cactus.) 



About thirty species of plants found in the "West Indies and tropical 

 America are arranged under the genus Melocactus, and resemble each 

 other closely in their leading characters. These are a globular un- 

 branched fleshy stem 1 to 2 or 3 feet in diameter, regularly ribbed from 

 tase to summit, the ridges bearing a, varying number of clusters of 

 spines and a cylindrical portion, termed "the cap," produced from the 

 apex of the stem, formed of a woolly substance, and closely set softer 

 spines than those on the main stem. Upon this the small flowers are 

 t)orne, tubular in form, and red or rose-coloured. All the species are 

 natives of hot regions, generally growing in rocky or sandy situations 

 exceedingly dry, but a few are said to be found near the coast or in salt 

 marsh districts. Only one species — namely, M. communis, is in general 

 cultivation, and this is probably owing to the fact that the plants are of 

 little or no horticultural value, though as curiosities they are remarkable. 



Gnlture. — The Melocactus is one of the most difficult of all to grow 

 successfully, and it is rare that a thoroughly healthy specimen is seen ; 

 indeed, imported plants that have " the cap " developed when received 

 eeldom live long, and the only specimens which have a chance of success 

 are those sent over in a young state or raised from seed here. A high 

 temperature, very porous soil, abundant drainage, and little water are the 

 chief points requiring attention, and when a plant assumes an unhealthy 

 appearance water must be withheld. 



Frojiagation. — Oifaets are seldom produced unless the crown or cap be 

 removed or damaged, or if the upper portion of the stem he cut off. When 

 the surface is partially healed offsets usually appear round the margins, and 

 these can be separated and grown on like those of other Caoteas. 



