27 
the parentage of these hybrids, however, have not been kept, and pub- 
lished statements of their parentage are often mere guesswork. Cer- 
tainly many of these hybrids have been obtained by crossing not 
only species but hybrids. This mingling of plants, themselves often 
of unknown or uncertain origin, has produced difficulties of determin- 
ation which no amount of study will probably ever overcome; and 
of all hybrid Azaleas the parentage only of this Wellesley plant is really 
known, a fact which certainly adds to its value and interest. 
The third Japanese species which is now well established in the Ar- 
boretum is Rhododendron reticuiatum, the oldest name for the plant 
more generally known as R. rhomb icum,. This plant is common over 
a large part of Japan, growing on open wind-swept hillsides, on the 
borders of the forest and in the shade of thick woods. The flowers 
are deep magenta color, red-purple or rose-color, and do not harmonize 
with those of several other Azaleas, but when R. rhomhicum is isolated 
or planted with white-flowered plants it is when in flower one of the 
most beautiful and distinct of all hardy Azaleas. A white-flowered 
form (var. aIMJiorum.) is known to Japanese botanists but this plant, 
which is said to be rare, is not in gardens. 
Early-flowered American Azaleas. Before the flowers of Rhododen- 
dron Vaseyi have entirely faded those of the two most widely distrib- 
uted species of eastern North America, R. nudijiorum and R. canes- 
cens, begin to open. These plants are common from New England to 
Texas; they have pink, very fragrant flowers which open before and 
as the leaves emerge from the bud, and very similar in general char- 
acter, will perhaps sometime be considered varieties of one species. 
They have been planted in considerable numbers in the Arboretum and 
grow equally well in open borders or in the partial shade of woods. 
Before their flowers fade those of the flame or yellow-flowered Azalea 
(R. calendulaceum) of the Appalachian Mountains, the most splendid 
of American Azaleas, will begin to open. 
The Rowan Tree, as the European Mountain Ash {Sorbus Aucuparia) 
is often called, has certainly not before in the Arboretum been more 
thickly covered with its wide clusters of white flowers or appeared to be 
in a most satisfactory condition. The largest and best of the Arboretum 
trees were sown by birds; there are several of these trees in different 
parts of the Arboretum and others are constantly springing up. Hand- 
some at this season of the year, they are more beautiful in the autumn 
when the branches bend under the weight of the clusters of scarlet 
fruit which birds eagerly seek. Several plants of a Chinese Mountain 
Ash, Sorbus discolor (sometimes called S. pekinensis) in the group of 
these plants on the left hand side of the Valley Road near the Swamp 
White Oaks, now covered with flowers, show the oramental character 
of this tree at this season of the year. This Mountain Ash is a tall, 
slender, hardy tree with leaves composed of narrow, long-pointed leaf- 
lets pale on the lower surface, broad open clusters of snow-white flow- 
ers, which are followed by small yellowish white fruits in drooping clus- 
ters. Sorbus alnifolia is also very full of flowers; it is a common Japan- 
ese tree, one of the species of an Old World section of the genus with 
