BULLETIN NO. 57. 
When this bulletin reaches its readers a large number of Rhododen- 
drons at the base of Hemlock Hill will be in flower. The flowers of a 
few have faded and those of others will continue to open during sev- 
eral days. The number of species of Rhododendrons with evergreen 
leaves which can be successfully cultivated in this climate is not large. 
The four species of eastern North America, Rhododendron maximum , 
R. Catawbiense, R. carolinianum and R. minus are all perfectly hardy, 
as are R. Smirnowii and R. caucasicum from the Caucasus, R. brachy- 
carpum from Japan and R. micranthum from China. The flower-buds 
of the last, however, have been destroyed by the cold of the past 
winter. The two European species, R. ferrugineum and R. hirsutum , 
are in the collection but they are not very satisfactory plants for this 
climate, and unless exceptionally favorable positions can be found for 
them they are not long-lived here. In recent years R. maximum has 
been largely planted in this part of the country, but the common Rho- 
dodendron of American gardens belongs to a race of hybrids which 
originated in England many years ago and are known as Catawbiense 
hybrids because they have been produced by crossing R. Catawbiense 
of the high summits of the southern Appalachian Mountains with R. 
ponticum of the Caucasus, and with R. arboreum and other Himalayan 
species. These hybrids are valuable in this country in proportion to 
the influence on them of R. Catawbiense, and it is found that varieties 
with broad leaves like those of the American plant are always hardier 
than the narrow-leaved varieties which show a greater influence of R. 
ponticum and the Indian species. The number of these hybrids, how- 
ever, which are really hardy in this climate is not large; among them 
Atrosanguineum (very early), Charles Dickens and H. W. Sargent 
(late) of red-flowered varieties are good plants; among the pink-flowered 
varieties none have proved so satisfactory as Mrs. Charles Sargent and 
Henrietta Sargent, similar in general appearance, but the latter with 
smaller and more compact flower-clusters and flowers of not quite such 
a perfect pink. Among the varieties with rose-colored flowers, Roseum 
elegans and Lady Armstrong are hardy and satisfactory; and among 
the varieties with dark purple flowers Purpureum grandiflorum, Pur- 
pureum elegans and King of the Purples are all hardy. Of the vari- 
eties with light purple flowers Everestianum is the best and one of the 
hardiest and most satisfactory of all these hybrids. Among the white- 
flowered varieties Catawbiense album (very early), Album elegans and 
Album grandiflorum can be safely used. Most of the hybrid Rhodo- 
dendrons in American gardens are of English origin, but a few years 
ago the Arboretum obtained in Germany a number of these hybrids 
raised in that country. These have proved very hardy and some of 
them promise to be valuable additions to the Rhododendrons which can 
be successfully cultivated here. The most distinct, perhaps, are Viola, 
with white flowers, Albert, with pale pink flowers, and Bismarck, with 
white flowers with small brown dots on the inner face of the cor- 
olla. The last has flowered profusely now every season for the last 
three years; the foliage and habit are good, and as it flowers early 
this variety is particularly valuable, for there are not many early white- 
flowered Catawbiense hybrids. Among the hybrid Rhododendrons which 
