4 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



and Dalla Torre and Harms, " Genera Siphonogamanim " (1901). 

 But as a matter of fact, the number of known species has increased 

 far faster than that. In " Index Kewensis" (1885) some 238 species 

 are listed (some of which are now regarded as synonyms or varieties) ; 

 the four supplements which have since appeared raise this number 

 (up to the end of 1910) to 391 ; and a fair estimate would put the 

 total number of species at present known at about 500. The large 

 increase during the last half-century is due mainly to the botanical 

 exploration of Mexico and of Western China (see pp. 8, 10). 



The great majority of these 500 species are not, and have never 

 been, in cultivation, and are known (especially the many recently 

 described Chinese species) only from dried specimens. A good 

 many of them are annuals, or of no horticultural value. But there 

 remain many handsome or interesting plants, which one would like 

 to see introduced into our collections. As regards the number of 

 species in cultivation, Dr. Maxwell Masters, in his account of the 

 cultivated Sedums * (1878), lists 65 species ; but a critical examination 

 of his list shows that of these only 44 were certainly examined by 

 himself, or, if not seen, were certainly correct. These are all in 

 cultivation still. Four more were apparently seen by him. Eleven 

 not seen by him I regard as doubtfully correct, and probably re- 

 ferable to species already in his list, while finally six of his species 

 are now to be set down as synonyms, additional species erroneously 

 named, or varieties. These last are : 



S. arboreum = S. moranense var. arboreum. 



S. Beyrichianum = 5. Nevii var. Beyrichianum. 

 S. Maximowiczii = 5. Aizoon. 

 S. pruinatum = S. rupestre. 

 S. sarmentosum = S. mexicanum. 

 S. stoloniferum = S. spurium. 



As the first, fifth, and sixth of these are not in his list under their 

 correct names, the number certainly in cultivation, according to his 

 paper, is raised to 47. At least half a dozen tender species (with which 

 his paper was not concerned) were also certainly in cultivation at 

 that time. 



As regards the present list, I went further afield than Dr. Masters, 

 and to the best of my ability ransacked the gardens of the world, 

 till the war put an end to such activities. European gardens yielded 

 a good many species unknown to Masters ; others came from the 

 Himalayas, China, and Japan, while important contributions of 

 Mexican species were received from Washington and New York. As a 

 result I have received and grown a total of 151 species, 13 of which 

 proved to be new to science, and have been described.f I know of 

 only four species which I believe to be at present in cultivation, 



* Masters, M. T., " Hardy Stonecrops : Sedums." Card. Chron, N.S. 10, 



187S. ii. 



■j- Journal of Botany, vols. 55, 56, 57. 



