This is also a numerous family, nearly all of which are hardy in the North and in the prairie States. The Amur barberry (Berberis Amurensis) is specially useful in lawn and park work. It grows rapidly into a defensive hedge or screen, and planted singly in certain positions it assumes a broad, spreading habit of growth, handsome in foliage; and when loaded with its scarlet fruit in autumn it is specially attractive. Fig. 98 shows its habit of growth. Berberis Thunbergii comes next in ornamental value for planting in near proximity to house, walks, and drives. It is not more than four feet in height, with regular compact form without pruning. Its leaves are small, numerous, and assume gorgeous colors in autumn. All the types are hardy, but the variety from the Amur valley in Asia, known as Maximowiczi, is the hardiest for the far North.
Fig. 98. - Amur barberry screen as grown in north Iowa. (After Gardner.)
The purple-leaved variety of the common barberry (B. vulgaris) comes third in value to give variety to groups and borders. It retains the purple color of leaves through the season. It contrasts finely with golden-leaved or lighter green leaves of trees or shrubs. To keep this fine variety in compact, bushy form it needs heading-in, while young, in the dormant season.
In the West the common barberry and the purple-leaved are troubled with the cluster-cup fungus on their foliage. But the first two named, and indeed all the Oriental species we have tested, are free from fungus disease of the leaves.