58 MISSOURI BOTANICAL GARDEN. 



have flowered, and their descriptions were collected by 

 Schumann and incorporated in his Monographia or succes- 

 sively published in the Monatsschrif t f iir Kakteenkunde by 

 various cultivators of cacti. 



A thorough study of the plants in question and their 

 various peculiarities has shown me that there exist a num- 

 ber of well defined and most natural subgenera. 



The subgenera here proposed are such as can be estab- 

 lished with our present knowledge. Some may be imper- 

 fect, like all first attempts. With the extending exploration 

 of Central and South America, and with our ever-increas- 

 ing knowledge, corrections will of course be made. 



My attention was first drawn to this by observing several 

 Cerei at La Mortola in Sir Thomas Hanbury's famous 

 gardens, and afterwards while arranging their flowers in my 

 herbarium. To my first obvious observations facts were 

 constantly being added until the whole scheme was worked 

 out. There exists a far greater variety in the characters 

 of flowers and fruits than I at first supposed. 



It is a well-known fact that many connecting forms exist 

 in Cactaccae, even between the greater genera. On account 

 of this Dr. Kuntze* reunites most of them under one single 

 genus, Cactus. There can be no doubt that connecting 

 forms w T ill also be found between the subgenera, but this 

 cannot affect the fact of their existence. Of course these 

 subgenera may be considered distinct genera by those who 

 accept the new genera of Crassulaceae recently published 

 by Britton and Rose.f Most of these subgenera have 



© 



distinct geographical areas. 



I am fully convinced that Engelmann was perfectly 

 right to include Pilocereus as a subgenus under Cereus. 



As it now stands, it is an artificial genus, which required a 



* Kuntze & Post, Lexicon Generum Phanerogamarum. (1904). 

 t N. L. Britton and J. N. Rose, New or noteworthy North American 

 Crassulaceae. Bull. New York Bot. Gard. 3 : 1-45. (1903). 



