THE PLUM IN KANSAS. 113 



13. Altogether, the Japanese plums constitute the most important 

 type of fruit introduced into North America during the last quarter 

 of a century, and they should receive careful tests in all parts of the 

 country. 



THE PLUM IN THE WEST. 



From Bulletin No, 50, Colorado Experiment Station. 



The genus Prunus, as now constituted, embraces those species 

 from which have been developed all our stone fruits — almonds, 

 peaches, nectarines, apricots, plums, and cherries. Its representa- 

 tives are widely distributed over the earth, and the number of species 

 given by different authors varies greatly. Bentham and Hooker, in 

 their "Genera Plantarum," place the number at about eighty. A 

 later work, the "Index Kewensis," recognizes 121 species, and records 

 290 names as synonyms. The 121 species here considered valid are 

 distributed as follows : Eastern hemisphere, 87 species, 15 of which 

 are credited to Japan and 12 to China; western hemisphere, 32 

 species, 21 of which belong to the United States and the region north ; 

 7 are credited to Mexico, and 4 to South America and the West 

 Indies; 2 species are recorded of unknown origin. 



Our American manuals record species of the genus as follows: 

 "Botany of California" (1876), 6 species; Chapman's "Flora of the 

 Southern States" (1883), 7 species; Coulter's "Manual of the Rocky 

 Mountain Region" (1885), 5 species, 1 variety ; Gray's "Manual," 

 sixth edition (1890), 10 species, 1 introduced variety; Coulter's 

 "Flora of Texas" (1891), 8 species; "The Britton and Brown Flora" 

 (1897), 16 native, 4 introduced species, 2 native and 1 introduced 

 varieties. Taken together, these floras recognize 27 native and 4 in- 

 troduced species, and 3 native and 1 introduced varieties. 



Of the native representatives of the genus, sixteen species and one 

 variety are true plums, or of such close affinity as to readily class with 

 them, while eleven species and two varieties are cherries or belong 

 with the cherry group. Nearly all the species enumerated in the 

 manuals are, or have been at some time, introduced into gardens and 

 cultivated, either for their fruits or as ornamentals, but the varieties 

 now catalogued by nurserymen and grown in orchards represent but 

 few species. Of the native cherries, only the shrubby Sand cherries 

 {P. pumila, P. hesseyi, and P. cuneata) are grown for fruit. The 

 wild Red cherry {P. pennsylvanica) is occasionally used as a stock 

 upon which the common sour cherries of European origin are grafted ; 

 it has also been used to a limited extent as a stock for some of the plums. 



Of the native plum group, three species {P. americana, P. hortu- 



