26 
after a trial of twenty-five years, to be perfectly hardy and first-class 
garden plants in eastern Massachusetts are R. Kaempferi, now consid- 
ered a variety of R. obtusum, R. japonicum and R. reticulatum, better 
known as R. rhomhicum. The first of these plants is the only red 
flowered Azalea which is hardy in this climate. Thousands of seedlings 
have been raised in this country in recent years and it will soon be- 
come common in eastern gardens. It has been largely used in the Ar- 
boretum, and late in May and in the early days of June its flowers 
furnish the most surprising and spectacular display of the year. The 
flowers are delicate, however, and when fully exposed to the sun lose 
their color; and this Azalea gives most satisfaction when it is planted 
in the shade of trees or on the northern border of a wood of conifers. 
In the Arboretum the most successful group of this Azalea is behind 
the Laurels (Kalmia) and in front of the Hemlocks at the northern 
base of Hemlock Hill. The plants bloom a week later than those in 
more exposed situations and their flowers last much longer in good 
condition. The tallest plants in the Arboretum are now eight or nine 
feet high and although growing in complete shade never fail to flower. 
Rhododendron japonicum has been growing in the Arboretum as 
long as Kaemfer’s Azalea, and by many persons it is considered a 
handsomer plant. It is a round-topped rather compact shrub usually 
not more than three or four feet tall, with flame-colored flowers three 
inches across. It is only in recent years that the value of this plant 
in American gardens has been recognized, for it was long supposed, in 
the Arboretum at least, to be one of the numerous forms of the short- 
lived and usually unsatisfactory hybrids sent to this country chiefly from 
Holland and known commercially as “Azalea mollis.” A beautiful 
yellow-flowered variety of R. japonicum (var. aureum) has been found 
in Japan, and a few plants have reached the United States, where 
two years ago it flowered for the first time in a Massachusetts gar- 
den. This plant promises to be an important addition to the number 
of hardy Azaleas which can be grown in this climate. A handsome 
race of hybrid Azaleas was obtained several years ago in Europe 
probably by crossing Rhododendron japonicum with the yellow-flowered 
Azalea of eastern China, usually known as R. sinense. To this race 
of hybrids the general name of R. Kosterianum has been given. The 
best known plant of this hybrid origin is probably the one called “An- 
tony Koster.” It is a handsome plant, but not always entirely hardy 
in this climate where it is usually short-lived. About eight years ago 
T. D. Hatfield, gardener of the Hunnewell Estate at Wellesley, Massa- 
chusetts, crossed R. japonicum raised from seeds collected by Professor 
Sargent in Japan with R. sinense raised from seeds collected by Mr. 
Wilson in eastern China. There can be no doubt about the parentage 
of this plant. This new Azalea, which has been named R. Kosterianum, 
“Miss Louisa Hunnewell” bears large clusters of orange-colored flow- 
ers which open as the leaves unfold; the plant is perfectly hardy, and 
the flower-buds were not injured by the exceptionally severe winters 
of 1917-18 and 1919-20. If anyone in the United States has raised a 
handsomer shrub it is unknown to the Arboretum. During the last 
seventy-five years several hundred different hybrid Azaleas have been 
made in Europe and the United States; accurate and reliable records of 
