A few other species are hardy in this climate. The most distinct 
and the handsomest of these is R. Smirnovii from the Caucasus. This 
is a large plant with dark green leaves covered below with a thick 
mat of nearly white felt, and large clusters of large bright pink flow- 
ers. This plant is perfectly hardy but it grows best in partial shade 
as our hot sun causes the leaves to curl in summer. If the right pos- 
ition can be found for it, however, this is one of the most beautiful 
of the evergreen Rhododendrons which can be grown successfully in 
eastern Massachusetts. Hybrids of this plant with some of the Cataw- 
biense hybrids are hardy and interesting plants. R. micranthum is 
another species which proves to be hardy here. It is a plant widely 
distributed from northern to western China and in its native country 
sometimes grows from six to eight feet high. The small leaves and 
small compact clusters of small white flowers look like those of a 
Ledum. There are a number of plants of this Rhododendron in flower 
at the base of Hemlock Hill and there are others on Azalea Path. 
The two dwarf Rhododendrons from the mountains of central Europe, 
R. ferrugineum and R. hirsutum, are in the collection and the latter 
is now in flower. These plants, however, are not very satisfactory in 
this climate, and unless exceptionally good positions can be found for 
them they are not long-lived here. Two hybrids, however, in which 
these European Rhododendrons have played their part are valuable 
garden plants in this climate. The first of these, R. myrtifolium, is a 
hybrid between R. hirsutum and R. minus , and is a very compact, 
round-topped shrub, sometimes growing to the height of four feet, 
with small flowers of a good shade of pink. The great value of this 
plant is in its compact habit and handsome foliage. The second 
of these hybrids, R. arbutifolium, is the result of a cross between 
R. ferrugineum and R. minus . This is a plant with a more open habit 
than R. myrtifolium and soon spreads into a wide low mass of hand- 
some foliage; the flowers are small and of an unattractive rose 
color, and the value of the plant is found in its ability to cover either 
sunny or shady banks and for this it is admirably adapted. This plant 
is usually found in nurseries under the name of R. Wilsonii, a name, 
however, which properly belongs to another hybrid between two Him- 
alayan species. 
Persons who study the Arboretum Rhododendrons with a view of 
establishing collections of these plants must remember that the position 
of the Arboretum collection on the northern and northeastern sides of 
a thick wood of conifers is an exceptionally favorable one for these 
plants, and that many of the Catawbiense hybrids now flowering in the 
Arboretum cannot be depended on in less favorable positions. The 
number of these hybrids which are really hardy in all situations 
in Massachusetts is not large. Some of them which have grown in 
eastern Massachusetts for many years and have proved perfectly hardy 
here, even in exposed positions, are among the red-flowered varieties, 
Atrosanguineum (very early), Charles Dickens and H. W. Sargent (late); 
among the pink-flowered varieties, Mrs. C. S. Sargent and Henrietta 
Sargent, similar in general appearance but the latter with smaller and 
more compact flower-clusters and flowers of a less perfect pink; among 
the rose-colored varieties, Roseum elegans and Lady Armstrong; among 
the dark purple-flowered varieties, Purpureum grandiflorum, Purpureum 
elegans, and King of the Purples; among the light purples, Everestia- 
num, one of the hardiest of these hybrids; among the whites, Cataw- 
biense album (early), Album elegans and Album grandiflorum (both 
