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REVISION OF THE GENUS CEREUS MILL. 77 



has a somewhat isolated position. The flower is far less 

 hairy, and the stems, when adult, are triangular. For this 

 reason it is generally placed under the Triangulares, but 



fl 



remove it far from those species. 



Most of the species of Selenicereus are garden plants, 

 much grown for the sake of their beautiful nocturnal 

 flowers, which sometimes have a delicious scent, as for 

 instance those of G. grandiliorus Mill., the well-known 



Q 



ght . ' ' Gereus MacDonaldi 



about the largest flowers. 



o 



Subsection III. Peniocereus A. Berg. 



Rootstock tuberous, stems slender. Flowers with a long narrow tube, 



nocturnal, white or red. 





Cereus (Peniocereus) Qreggii Engelra. 1. c. 96. —Texas, North Mexico. 

 C. (Peniocereus') striates Brandg. 1. c. 134. (= C. Diguettii Web. 1. c. 

 30 ?). — Baja California. 



Of these two (or three?) species, G. Greggii Engelm. 

 is the best known plant. It flowered last summer at La 

 Mortola (see Monatsschrift fiir Kakteenkuncle, 1904, p. 

 134). The stems are covered with short velvety hairs. 

 The tube of the flower is broader than in Engelmann's 

 excellent plates (Cact. Bound, pi. 63, 65). 



Subsection 



gelni. in Additions to 



the Cactus Flora etc.; Coll.. Works. 225. 



Stems elongated, S-4-angled. Flowers white, nocturnal; tube with 

 a few scales and stiff bristles. 



Cereus (Acanthocereus) Baxaniensis Karw. 1. c. 98. (= C. princeps 

 Hort. = C. acutangulus Otto = C. variabilis Engelm.). —Central 



America. 



Gereus Baxaniensis Karw. is a very variable plant, a 

 fact which accounts for the numerous synonyms under 

 which it has been described by different authors. Young 



