A SYSTEMATIC REVISION OF THE GENUS CEREUS MILL. 



BY ALWIN BERGBR. 





Most species of Cereus, etc., have been named and de- 

 scribed by their authors from small specimens in cultiva- 

 tion. Neither flower nor fruit of many of them has until 

 now been known. Whilst this state of things lasted, a 

 real botanical treatment of the genus proved to be an 

 impossibility. Every author who had to deal with the 

 genus felt obliged, for the sake of bringing some order 

 into the arrangement, to make it entirely dependent upon 

 external characters of the habitus of the plants. Schu- 

 mann, the most recent monographer of Cactaceae, did 

 likewise, grouping the species according to the size, form 

 and color of their stems into thirty "Reihen," to which he 

 added in his " Nachtrage M two more. 



Engelmann was the first who made the flower and fruit 

 the chief character to depend upon, when he founded his 

 genus E chinocereus * This he afterwards reunited! with 

 Cereus together with Lepidocereus, Eucereus and Pilo- 

 cereus, as subgenera. Pilocereus was established as a 



genus by Lemaire, and C ephalocereus by Pfeiffer. In their 

 original form these two genera were identical. In 1860 

 Lemaire published Aporocactus, and in 1861 Cleistocactus. 

 Philippi, the famous explorer of the Chilian flora, founded 

 at the same time his genus Eulychnia. In 1897 Console's 

 Myrtillocactus , founded upon Cereus geometrizans, was pub- 

 lished. But these genera found little favor with other 

 botanists. 



Since then many Cerei cultivated in European gardens 



* Engelmann in Wisliz. Tour North. Mexico. 91. (1848). 



t Engelmann inCacteaeof PL Fendlerianae (1849), Mem. Amer. Acad. 



4: 50; Coll. Works. 114. 



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