34 
small leaves and small clusters of minute flowers; and there is one in 
which the corolla is deeply divided into narrow lobes (var. polypetala). 
A form with broad, handsome, Rhododendron-like leaves (var. obtusata), 
rarely flowers, and another with a six-lobed corolla has recently been 
found growing on the Blue Ridge in North Carolina. The Laurel col¬ 
lection is easily and quickly reached from the Walter Street and South 
Street entrances of the Arboretum. 
Rhododendrons. Although the hot weather of last week ruined the 
flowers of the early Rhododendrons and although the late flowering 
species and hybrids have not yet opened, a large number of the varie¬ 
ties of the Catawbiense hybrids are now in bloom. Persons who may 
desire to cultivate Rhododendrons must remember that they, including 
nearly all Azaleas, cannot live in soil impregnated with lime and that 
with the exception of the native R. maximum they are not hardy north 
of Massachusetts, and that south of Maryland, except at high altitudes 
on the Appalachian Mountains, the summers are too hot for them. The 
range therefore in eastern North America where these plants can be 
successfully cultivated is comparatively small, but probably the north¬ 
west coast of North America from southern British Columbia to north¬ 
ern California is as well suited for these plants as any part of the 
world, and in this region there can be grown in addition to all the varie¬ 
ties common in European gardens the Himalayan and Chinese species 
which here in the east can only be kept alive in glass houses, and in 
Europe thrive only in a few exceptionally favorable places like Cornwall 
or in the neighborhood of the Italian Lakes. 
Rhododendrons, although they are moisture-loving plants, do not 
thrive in undrained positions; they do best in soil in which loam, peat and 
sand have been equally mixed, although peat is not always essential 
to the successful cultivation of these plants. They should be planted 
where the roots of trees cannot take away moisture from them, and 
the best position for these plants is on the north side but not too near 
coniferous trees as they have been planted in the Arboretum. In such 
positions they are protected from the direct rays of the sun in March 
and April, for in this climate where the roots are in frozen ground in 
winter and therefore cannot take up moisture, it is important to reduce 
as much as possible winter and early spring evaporation from the 
leaves. It is this evaporation from the leaves of evergreens growing 
in frozen soil which makes it impossible to keep alive many of them 
in this part of the country; and this is the reason why it is desirable 
here to water thoroughly Rhododendrons just before the ground freezes 
in the autumn. Of the species of evergreen Rhododendrons only the 
eastern American R. maximum, R. catawbiense, R. carolinianum and 
its variety with white flowers (var. album), R. minus and its moun¬ 
tain form, 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 
sometimes for a number of years, but they are usually short-lived and 
unsatisfactory 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 
