108 CACTUS CULTURE FOR AMATEURS. 



treatment. Interesting as being the plant employed in the culti- 

 vation of cochineal. It is one of the easiest to manage, requiring 

 a rather dry atmosphere, plenty of light, and a temperature not 

 lower than 50 deg. in winter. 



O. cor ru gat a. 



Stem not more than 2 feet high ; joints cylindrical, wrinkled all 

 over, about 2 inches long, covered with cushions of white hair or 

 bristle-like spines. Flowers H inches across, reddish-yellow, pro- 

 duced in August. May be grown in an ordinary greenhouse, on a 

 shelf near the glass, and exposed to full sunshine. 



O. curassavica. 



Branches short, spreading ; joints club-shaped, dark grc en, Leaving 

 numerous cushions of bristles, and long, white, very sharp-pointed 

 spines. Flowers 3 inches across, greenish-yellow, borne on the 

 young joints in June. Introduced from Curassoa in 1 690. Requires 

 stove treatment. Long cultivated in gardens. Several varieties of 

 it are known, differing in habit, length of spine, or colour of flower. 



O. cylindrica. 



Stem and joints cylindrical, covered with spindle-shaped 

 tubercles, crowned with tufts of fine, hair-like, whitish spines, 

 one or two in each tuft being stiff, and sharp as needles. The leaves 

 are fleshy, cylindrical, 1 inch or more long, and they remain on the 

 plant longer than is usual in Opuntias. Flowers crowded on the 

 ends of the branches, each 1 inch in diameter, scarlet, developed in 

 June. Said to grow to a height of 6 feet or more in its native 

 habitat, but under cultivation it is rarely seen more than 3 feet 

 high. Introduced in 1799. It requires stove treatment, but rarely 

 flowers under cultivation. Var. crutata has cockscomb-like stems, 

 with the leaves and white hairs growing all along the top of the 

 comb. 



O. Davisii. 



Stems somewhat horizontal, 1 \ feet in height ; joints 4 to 6 inches 

 long, \ inch thick ; tubercles not prominent, bearing cushions of 

 very slender bristles, forming a kind of brush, from amongst which 

 the spines spring. Longest spines l\ inches, covered with a loose 

 glistening sheath. Flowers 2 inches in diameter, greenish- brown. 

 New Mexico, introducd 1 883. It forms a compact, shrubby plant, 

 if kept in an intermediate house during winter, and placed in the 

 open in full sunshine during summer. It is named after Jefferson 

 Davis, the American Statesman. 



O. decumana. 



The largest species known. At Kew it is represented by a plant 

 12 feet high (it would grow still taller if the house were higher). 

 Stem hard, woody, brown-barked, bearing an enormous head of 



