47 
Oxydendrum arboremn, the Sour Wood or Sorrel-tree, so-called from 
the acrid taste of the leaves, is the only American tree in the Arbor¬ 
etum which flowers in August. It is a native of the Appalachian for¬ 
ests from southwestern Pennsylvania and is most common on mountain 
slopes, but reaches the coast of Virginia and North Carolina. The 
Sorrel-tree, which is perfectly hardy in New England, is a beautiful 
tree with bright green shining leaves which turn bright scarlet in the 
autumn, white Andromeda-like flowers erect on the branches of spread¬ 
ing or slightly drooping terminal clusters, and pale capsular fruits 
which in the autumn are conspicuous among the brilliant leaves. There 
is a group of these trees among the Laurels at the base of Hemlock 
Hill. 
Summer Flowering Shrubs. Many shrubs with conspicuous flowers 
bloom in the Arboretum during the summer months. The list includes 
the Heathers ( Calluna vulgaris), and several species of Genista and 
Cytisus. Of this European group the handsomest which can be grown 
here is the bright yellow-flowered Cytisus nigricans , the yellow-flow¬ 
ered C. capitatus, the white-flowered C. leucanthus and the yellow- 
flowered Woad Wax and its varieties ( Genista tinctoria), too well known 
in Essex County, Massachusetts, where escaped from cultivation it has 
ruined many hundred acres of hillside pastures. The Lespedezas with 
their abundant purple, pea-shaped flowers, and the handsomest of the 
Chinese Buddleias are still to bloom, as is the very hardy Acanthopa- 
nax sessiliflorum, a vigorous shrub of eastern Siberia, most conspicu¬ 
ous in winter when the compact round clusters of the shining black 
fruits are on the ends of the branches. The Japanese Hydrangea 
paniculata and its varieties, and the Hydrangeas of North America 
produce here the showiest July and August flowers. The early-flow¬ 
ered forms of Hydrangea paniculata (var. praecox ) which is the hand¬ 
somest of the group, is already in flower; and all the American species 
are blooming or just opening their flower-buds. The most popular of 
these American plants is the form of H. arborescens (var. grandijlora) 
with snow-bail-like heads of white sterile flowers. There is a similar 
abnormal form of another of the American species, H. cinerea. More 
beautiful, and one of the handsomest of the genus, H. quercifolia will 
flower this month in the Shrub Collection. This is an unusual event 
for this shrub, which is a native of the southern states, is frequently 
killed to the ground here. In the middle and southern states it is an 
important and valued garden ornament. Of the American Hydrangeas 
which are perfectly hardy in the north the handsomest is H. radiata , 
a native of mountain slopes in North and South Carolina, once a pop¬ 
ular garden plant but now rarely cultivated. It is a broad, round- 
topped shrub with leaves of ample size, dark green above and silvery 
white below, and broad flat heads of flowers surrounded by a ring of 
white neutral flowers. 
Amorpha canescens, the Lead Plant, is beginning to open its small, 
violet-colored flowers arranged in long, narrow clustered spikes, which 
are conspicuous by the contrast with the color of the leaves and 
branches and are thickly covered white gray down. This plant is a 
native of the Mississippi valley where it grows on low prairies from 
Indiana and Minnesota to Texas. 
