CACTI 



21 



havior might throw further light on the relationship of stem and 

 fruit. 



Of what advantage is the tuberous root, especially to certain 

 species of Opuntia ? Tuberous and fibrous-rooted forms grow under 

 identical conditions. A comparison of the development of these 

 structures in seedlings and in vegetatively produced plants would 

 be an interesting study. 



Why do fruits of the proliferous-fruited species (Cylindropuntia) 

 each succeeding year bud forth into new fruits while, if detached 

 from the plant they give rise to vegetative growth? A comparison 

 of the behavior of the seed in the cluster of fruits with that in the 

 fruit which has become incorporated in the plant body might give 

 interesting information. 



Any of these subjects can be easily investigated by persons with 

 interest and intelligence. It would seem that the cactus fancier 

 has plenty of interesting problems to work on besides simply amass- 

 ing a collection of unique, grotesque, or ornamental cacti. 



CULTIVATED FORMS 



The following list contains the names of most of the cacti now in 

 cultivation in the United States. Many other forms are to be found 

 in collections, but they are not at all common. Those in the list are 

 grouped with reference to their habits of growth. Measurements, 

 where given, refer to mature plants and are only approximate. The 

 list, arranged as it is with reference to size, will serve as a guide to 

 prospective purchasers in dealing with collectors and traders. 



The names used have been rearranged to accord with the latest 

 monograph, which, on account of its recent publication and high 

 cost, may not be available to most cactus growers and dealers. In 

 order to make the lists more readily usable by those who do not 

 possess the last work on the subject, the names in use up to and includ- 

 ing Schumann's monograph {22) are given in parentheses. The 

 same practice has been generally followed in the text. 



COLUMNAR FORMS OF CACTI 



Tall — more than 6 feet high 



Camegiea (Cereus) gigantea. 



Cephalocereus (Pilocereus) arrabidae (ex- 



erens). 

 Cephalocereus (Pilocereus) chrysacanthus. 



Cephalocereus (Pilocereus) cometes. 



Cephalocereus (Cereus ) euphorbioides. 



Cephalocereus (Pilocereus) hoppenstedtii. 



Cephalocereus (Pilocereus) lanuginosus. 

 Cephalocereus (Pilocereus) leucocephalut. 



(houlletii). 

 Cephalocereus 



tus). 

 Cephalocereus 



(Pilocereus) nobilis (stric- 



(Pilocereus) polylophus. 

 Cephalocereus (Pilocereus) russelianus. 

 Cephalocereus (Pilocereus) senilis. 

 Cereus aethiops (coerulescens) . 

 Cereus azureus. 

 Cereus columnaris. 

 Cereus forbesii (validus). 



Cereus hildmannianus. 



Cereus jamacaru. 



Cereus peruvianus. 



Cleistocactus baumanni. 



Escontria chiotilla. 



Lemaireocereus ( Cereus ) dumortieri. 



Lemaireocereus griseus (Cereus eburneus). 



Lemaireocereus (Cereus) stellatus. 



Lemaireocereus (Cereus) thurberi. 



Lemaireocereus (Cereus) vceberi. 



Lophocereus (Pilocereus) schottii. 



Myrtillocactus ( Cereus ) geometrizans. 



Nyctocereus (Cereus) serpentinus. 



Opuntia cereiformis. 



Pachycereus (Cephalocereus) chrysomallus. 



Pachycereus (Cereus) marginatus. 



Pachycereus (Cereus) pectenaboriginum. 



Pachycereus (Cereus) pringlei. 



Trichocereus (Cereus) macrogonus. 



