Complimentary 
NEW SERIES VOL. V 
NO. 7 
ARNOLD ARBORETUM 
HARVARD UNIVERSITY 
BULLETIN 
OF 
POPULAR INFORMATION 
JAMAICA PLAIN, MASS._JUNE 5. 1919 
Rhododendrons. The flowers of some of the early flowering ever¬ 
green Rhododendrons have already faded and those of R. maximum 
will not be in bloom for several weeks, but when this Bulletin reaches 
its Massachusetts readers a large number of the varieties of the Cataw- 
biense hybrids will be in flower; and these plants are carrying this 
year an exceptionally large number of flower-buds. Of the species of 
evergreen Rhododendrons only the eastern American R. maximum , R. 
catawbiense, R. carolinianum, the mountain form of R. minus, the 
Caucasian R. Smirnovii and R. caucasicum , at least in some of its 
forms, are truly hardy in Massachusetts. The two species of the 
European Alps, R. hirsutum and R. ferrugineum can live here some¬ 
times for a number of years but they are usually short-lived and un¬ 
satisfactory plants in this climate. The Japanese R. brachycarpum 
formerly lived in Massachusetts gardens for many years and longer 
trials will probably show that it can be successfully cultivated in this 
climate. Including this still doubtful Japanese species and the two 
little European species, there are only nine species of this great genus 
of several hundred species hardy in this climate, and there is little hope 
that another species able to support this climate will be found. The 
poverty of our gardens in these plants appears when the Arboretum col¬ 
lection is compared with that in a garden in Cornwall in England, in 
which some three hundred and sixty species of these plants are grow¬ 
ing and in which on a day in May of this year sixty-five species were 
in flower. Such a collection, and perhaps even a better one, can be 
made in a garden in the neighborhood of Portland, Oregon, or in some 
favorable place on the shores of Puget Sound, but the sooner it is real- 
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