Æsculus (Horse-Chestnut).—The common representative of this requires little or no pruning, but the other species are benefited by a thinning out of misplaced and useless branches in late summer to allow light and air to the centre of the tree. This is especially important to all the Æsculus in a young state. Æsculus parviflora should have a good thinning if the branches or suckers become at all thick, cutting all growths not required clean away from the base.
Akebia.—"Akebia quinata has flowered here, on an east wall, profusely for the last seventeen years, under the following pruning treatment: Cover the space allotted with the strongest shoots, and when new growth pushes from the eyes or spurs in the spring, do not regulate it, but summer-prune away all superfluous growth before it gets entangled. It is from 'spurs' that the flowers are produced, and the more these are kept clear, the more matured they become, and flower correspondingly."—E. M. in The Garden.
Amelanchier.—These should be pruned after the flowers are past, the removal of badly-placed and weakly shoots being all that is required. If the plants are becoming too large, they can be shortened back at the same time.
Amorpha.—If flowers are desired of A. fruticosa it should be kept thinned out, and not be cut back; but the flowers are not showy, and it is usually kept cut down every winter for the sake of its foliage. A. canescens should be cut down each spring to within two or three eyes of the old wood, as it flowers best on the young growth.
Andromeda.—The only recognised species of this genus is A. polifolia, which requires no pruning.
Aralia.—These should be kept to a single stem until they have attained a height of 6 to 8 feet, after which they may be allowed to branch, or be still kept to a single stem, as may be desired.
Arbutus.—An evergreen genus which requires no pruning.
Aristolochia.—A genus of climbers which succeed best if the shoots are not allowed to become too thick. The weakest should be cut away in winter.
Artemisia.—This genus is best known by its common representative, the Southernwood, but this and the other Artemisias should be cut down annually in a young state. When older, an occasional thinning out of the shoots in winter is sufficient.
Baccharis.—Of this, B. halimifolia flowers on the young wood and should be cut back annually, while B. patagonica should not be pruned at all.