84 THE FANTASTIC CLAN 



spines, which are very numerous. The stems grow to about 

 fifteen inches tall, four inches or less in diameter with a 

 rounded-off top, singly, or branched above. The cylinder is 

 composed of about twenty-four ridges well covered with very 

 sharp radials, but with no central spines, a characteristic un- 

 common in the Hedgehog group. There are great numbers 

 of radially placed spines, closely pressed to the sides of the 

 stem. They are arranged in two comb-like groups, one on 

 each side of the areolas, and interlock with thorns of adjacent 

 spine clusters. This makes a dense spine layer over the entire 

 surface of the plant. These spines are less than a half-inch 

 long, and have swollen bases. They form in many colored 

 zones, or whitish, yellow, rose-purple to maroon-purple bands 

 about the plant. The flowers are about three inches long and 

 as wide when full open, and have some forty petals and 

 thirty sepals. The petals have pointed tips and are bright 

 rose-purple with yellowish bases. The fruit is covered with 

 many spines, is about the size of a strawberry, fleshy and 

 sweet. The rigidissimus invariably grows along the rock 

 ridges and rocky foothill slopes at altitudes of thirty-five 

 hundred to fifty-five hundred feet, the roots growing among 

 the rocks. Its distinguishing characteristic is the many col- 

 ored bands of the spines around the plant, suggesting a 

 rainbow. 



How to grow 



Rainbow Cacti are not injured in zero temperatures out 

 of doors, but with colder weather than this they require 

 some protection. They may be grown in cool, dry, sunny 

 conservatories. The Rainbow is one of the most difficult 

 of the cacti to grow under cultivation. Unless planted in 

 rocky soil, preferably early in spring, it will grow for only 

 a year or two. Young plants transplant more readily than 

 older ones, and neither the roots nor the stems should be in- 



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