MAMILLARIA. 93 



M. tetracantha. 



Stem the size of an ostrich's egg, thickly studded with small 

 conical tubercles, woolly at the base, crowned with four spreading 

 spines, J inch long, rather stout, straight, brown when young, 

 almost white with age. Flowers numerous, small, bright rose, 

 with orange-yellow anthers, developed in July. Mexico. Requires 

 the same treatment as M . cirrhifera, to which it is related. 



Fig. 49. Mamillaria sulcolanata. 



M. tuberculosa. 



Stem 6 inches high by 2 inches in diameter, conical, usually 

 surrounded at the base by globose offsets ; tubercles .] inch long, 

 closely set in spiral rows, crowned with slender, hair-like, white 

 spines, i inch long ; central spines three or four. The spines fall 

 from the old tubercles, which gradually harden to a cork-like 

 substance. Flowers produced in the apex of the stem, 1 inch long 

 %nd wide, daisy-like, pale purple, succeeded by red, oval benies. 

 <\bout five flowers are developed on each stem annually May and 

 June. Mexico. Tt thrives in an ordinary green ^use, on a shelf, 

 in full sunshine. 



M. turbinata. 



Stem globose, depressed at top, about 3 inches in diameter, pale 

 glaucous-green ; tubercles quadrangular, flattened at the apex, and 

 bearing, when young, from three to five erect, slender, hair-like 

 apines, which fall off soon after the tubercles ripen, exposing little 



