CACTUSES AND OTHER SUCCULENTS III 



cactus are covered with small tubercles (mammillce) arranged 

 in spirals, and externally terminating in spines. The flowers 

 are mostly small, and have a wide range of colour — white, 

 yellow, orange, pink, red, and purple. M. clava is the finest. 



Fig. 47. — Mammillaria dolichocentra. 



Mesembryanthemum (Fig Marigold). — A genus remark- 

 able for its variety of widely different forms, many of them 

 most extraordinary. Some, such as the M. crystalliniwi (Ice 

 plant), are annuals, others perennials ; some are deciduous 

 shrubs, others evergreen; some might be mistaken for cactuses, 



