4 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 
and Dalla Torre and Harms, " Genera Siphonogamarum " (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 Hsted (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. arbor eum. 
S. Beyrichianum = 5. Nevii var. Beyrichianum. 
S. Maximowiczii = S. Aizoon. 
S. pruinatum = S. rupestre. 
S. sarmentosum = S. mexicanum. 
S. stoloniferum = 5. 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.! I know of 
only four species which I believe to be at present in cultivation, 
♦ Masters, M. T., " Hardy Stonecrops : Sedums." Gard. Chron. N.S. 10, 
1878, ii. 
I Journal of Botany, vols. 55, 56, 57» 
