47 
group must be considered one of the great contributions made by man 
to gardens in the last fifty years. Lemoine produced other hybrids 
like Conquete, Nuee Blanche, Rosea and Perle Blanche of rather un- 
certain origin. They are all interesting but perhaps less beautiful than 
some of the forms of P. Lemomei. 
A hybrid probably between Philadelphus grandiflorus from the Ap- 
palachian region and one of the western species appeared in the Arbor- 
etum a few years ago and has been named P. splendens. It is a large 
shrub with erect stems and large scentless flowers, and is one of the 
handsomest Syringas in the Arboretum collection. Another hybrid, 
supposed to be between P. pubescens (P. latifolius) of the southeastern 
United States and the Himalayan P. tomentosus, grows to a larger 
size than other Syringas. Plants from twenty to thirty feet high of 
this hybrid can sometimes be seen in old Massachusetts gardens. It 
is impossible to name all the different species, varieties and hybrids of 
this genus now growing in the collection in one of these Bulletins, and 
persons interested in flowering shrubs will do well to visit the collec- 
tion at this time and see the plants themselves. Many of them are 
in the general Shrub Collection but a larger number is in the special 
Philadelphus collection on the right-hand side of Bussey Hill opposite 
the Lilacs. 
Late Rhododendrons. Two dwarf hybrid Rhododendrons are now in 
flower and deserve consideration as rock garden plants. The first, P. 
arhutifolium, is a dense shrub spreading into broad masses of branches 
occasionally four feet high, small, acute, evergreen leaves, and small 
rose-purple flowers in small compact clusters. It is considered to be 
a hybrid between R. ferrugineum of the European Alps and R. minus 
(P. punctatum) of the southern Appalachian region. P. arhutifolium 
is better known in gardens as P. Wilsonii^ a name which belongs to 
a hybrid between two Himalayan Rhododendrons. It is sometimes also 
cultivated under the names of P. daphnoides, P. Hammondii, and P.' 
oleaefolium. The second of these plants, P, myrtifolium, is believed 
to be a hybrid between the other European alpine species, P. hirsutum 
and P. minus. It is a smaller and more upright growing plant than 
P. arhutifolium and has smaller and broader leaves and much hand- 
somer rose-pink flowers also in compact clusters. It is not usually 
quite so hardy as P. myrtifolium but was uninjured last winter, and 
the plants are now covered with flowers. 
Periploca sepium. To most gardeners who live where the climate is 
less severe than it is in eastern Massachusetts Periploca graeca, a tall, 
vigorous, climbing plant with dark green leaves and curious green and 
brown flowers, is familiar. Less known is the species from northern 
China, P. sepium^ which has more slender stems which do not 
climb so high, lanceolate, green and very lustrous leaves and flowers 
similar to those of P. graeca but only about three-quarters of an 
inch in diameter. It is perfectly hardy here and can now be seen 
covered with flowers on one of the trellises between the Shrub Col- 
lection' and the parkway. It produces many suckers from the roots 
and there is therefore no reason why this beautiful plant should remain 
so little known in gardens. 
