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PLANTS AND MAN 



the prickly pears differing from them by having cylindrical 

 rather than flattened stems. 



The smallest of the cacti are the globular pincushion cacti 

 which rarely grow more than a few inches in height; each in- 

 dividual is marked by rows of spirally arranged tubercles, bearing 



Fig. 271. — The barrel cactus of California often grows to a height of six feet, and 

 to a diameter of a foot or more. 



spines. The flowers are white, cream, purple or rose; various 

 species are known as fish-hook cacti or devil's pincushions. 



The HEDGEHOG CACTI are larger plants with ribbed cylindrical 

 stems, armed with clusters of long spines; the purple or red 

 flowers often attain an inch or more in diameter. Related species 

 include the delicately spined lace cactus common in Texas. 

 Larger than the hedgehog cacti are the barrel cacti of the 

 California and Nevada deserts; species may reach a height of 



