456 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



twelve to twenty vertical, angular ridges, studded with spines. The 

 remarkable feature of the plant is its inflorescence, on account of which 

 it is called the " Turk's-cap Cactus," "Englishman's Head," and 

 "Pope's Head." It consists of a cylindrical mass of whitish cotton-like 

 substance" interspersed with slender red spines, among which the small 

 red flowers appear, succeeded by small red fruits. The plant is difficult 

 to grow, is almost always imported, and dies after flowering for some 

 time. It is native of St. Kitt's and other islands of the West Indies. 

 The other species are similar. 



Mamillaria. — This genus is chiefly Mexican and contains some of the 

 most popular of Cactaceae (figs. 73, 74). It is readily recognised by the 



FlU. 74. MAMILtLAKIA SCHMIDTII, SIXTEEN YEARS FROM SEED. 



globose or cylindrical stems closely studded with conical or mamillaeform 

 tubercles, at the apex of each of which there is usually a tuft of radiating 

 spines. This tuft of spines is sometimes wonderfully beautiful- either 

 \ [( wed singly or in the mass- and the ornamental character of the plant 

 is usually determined by them. Schumann makes ninety-nine species, 

 natives of Mexico and the warmer parts of North America, rarely Brazil, 

 Bolivia, and the islands of the West Indies. 



Coryphanta is a subgenus with furrowed tubercles. In Mamillaria 

 proper they are never furrowed. 



Ariocarpus,* Scheidw. (Anhalonium, Lemaire) is best regarded as a 

 distinct genus. It is readily distinguished by its triangular or sub- 



* A. Williamaii and A. Lcwinii do not belong here. The former is placed in 

 Echi/nocactus (section Lophcpkora) by Schumann, and the latter in the same genus 



