388 



DOMESTIC BOTANY. 



The extreme variation in tlie different groups of species 

 admits of their being readily arranged under sections, ^vhich 

 some botanists consider should be regarded as distinct 

 genera. The following are examples : — 



1. Opiintia (Indian Fig). 



Stems decumlent or erect, branching ; branches consisting of 

 flat, convex, or round groicths, jointed end to end. Flowers 

 generally yellow and rosulate. 



Indian or Prickly Pear (Opuntia Tuna and 0. Ficus in- 

 dica). Tall growing species are naturalized in Madeira, North 

 and West Africa, and many parts of Asia, giving a picturesque 

 appearance to the old walls of Jerusalem. They attain the 

 height of 20 feet, and are hard, Avoody, and spinose, forming 

 impenetrable hedges, as is also the case with other allied species. 

 Their fruits are of a red or yellow colour, being about the 

 size and shape of the common fig ; and are esteemed for their 

 cooling juice, which contains sugar. These plants, w^ith 

 0. vulgaris, abound on the lava slopes of Mount Etna, and are 

 the pioneers of cultivation, their roots penetrating and break- 

 ing up the lava, the decayed parts in time forming a rich 

 vegetable mould, on which vineyards are planted. The fruit 

 is collected in large quantities, and sold in the markets, form- 

 ing an extensive article of food to the inhabitants. It grows 

 abundantly in other parts of the South of Europe, and in 

 Algeria, from which place the fruits are imported to this 

 country. When old, the fibrous parts of the joints of the 

 stems become hard and firm, and are made into ornamental 

 articles. 



Cochineal Plant {Opuntia cochinellifera). A native of 

 Mexico, where it is cultivated to a large extent, in what are 

 called the Nopal Plantations, for the breeding of the Cochi- 

 neal insect ; but 0. Tuna and other species are also grown 

 for the same purpose. They are now cultivated in Madeira 

 and Teneriffe, from w^hich places a considerable quantity 

 of cochineal comes to this country. The cochineal insect 

 is like a house-bug, and has the same appearance on the 



