72 CACTUS CULTURE FOR AMATEURS. 



was also a magnificent specimen in the Oxford Botanic Gardens, 

 with a stem 16 feet high ; and it is stated that this plant had been 

 in cultivation in England a hundred years at least. A plant 

 twenty-five years old is quite small, and. from its slowness of 

 growth, there is reason to believe that a stem 20 feet high would be 

 several hundred years old. The flowers of P. senilis are not known 

 in English collections, the plant being grown only for its shaggy 

 hairiness. 



