With the exception of species of Rhipsalis the cacti are strictly 

 indigenous to the Western Hemisphere. The introduction of these 

 plants into Europe evidently began soon after the discovery of Amer- 

 ica. The English, Dutch, and Spanish traders, who early carried on a 

 commercial business in the West Indies, South America, Central 

 America, and Mexico, took back to their respective countries many 

 interesting and curious plants then new to the gardens and plant 

 lovers of Europe. 



In the earliest published reports of the introduced and cultivated 

 plants of European gardens accounts and in many instances illustra- 

 tions of cacti are frequently found. Additional plants gradually were 

 introduced, until at the time Linnaeus published his Species Plantarum 

 (IS) 2 he recognized 22 species, all of which he included under the 

 generic name of Cactus. They were commonly known as thistles, 

 probably from the spiny character of their protective armor. The 

 smaller, more or less globose forms were called melon thistles, whereas 

 the taller ones were called torch thistles or candle thistles. The 

 Indian fig (Opuntia ficus-indica) and several other species of Opuntia 

 were introduced into the Mediterranean region at a very early elate. 



From the time of the cited publication by Linnaeus the steady 

 introduction of new plants was continued from the Western Hemi- 

 sphere into Europe. These importations included many forms of 

 cacti. Miller (14) enumerates a number of species distinct from 

 those recognized by Linnaeus. Others were described and published 

 from time to time by Haworth (5, 6, 7), Link {12), Salm-Dyck 

 (19, 20, 21), De Candolle (2, 3, 4), Lemaire (9, 10, 11), Pfeiffer 

 (15, 16, 17), and others. The most extensive modern systematic 

 works are by Schumann (22) and Britton and Rose (1). 



It was not until within the last half century that any special in- 

 terest in cacti was manifested in North America. A few species, 

 such as the night-blooming cereus (Selenicereus (Cereus) grandi- 

 florus and jS. pteranthus (Cereus nycticallus) , queen-of-the-night 

 (Phyllocaotus acuminatus) , crab cactus (Zygocactus (Epiphyllum) 

 truncatus), and the rat-tail cactus (Aporocactus (Cereus) flagelli- 

 formis) had become favorites as house plants. General collections of 

 this group of the plant world by George Engelmann laid the founda- 

 tion for the large collection at the Missouri Botanical Garden at St. 

 Louis, Mo. Similar interest manifested by Asa Gray added mate- 

 rially to the. collection at the botanical garden at Cambridge, Mass. 

 As the public became more acquainted with these bizarre forms of 

 vegetation, a livelier interest in them sprang up, and many persons 

 throughout the country began to gather private collections. Fanciers 

 became so numerous that in certain localities clubs or societies were 

 organized, where ideas and experiences as to the culture of these 

 plants could be discussed and specimens exchanged. Experience 

 was the high-priced teacher from whom these collectors had to gain 

 their knowledge. Similar organizations were formed in Germany, 

 where amateur collectors were numerous, and also in France and in 

 England. Many articles have been published in the horticultural 

 journals of these countries describing proper methods of propagation 

 and culture, and William Watson, of the Kew Gardens, England, 



2 Reference is made by number (italic) to " Literature cited." p. 24. 



