Achillea.—Handsome composite plants, the stronger ones of easy culture in common soil. A. Eupatorium and filipendula, 3 to 4 ft., have showy yellow corymbose flowers; A. rosea, 2 ft., rosy-crimson; and A. Ptarmica flore-pleno, 2 ft., double white flowers. Others suitable for front lines or rockwork are A. tomentosa, 9 in., bright yellow; A. aegyptiaca, 1 ft., silvery leaves and yellow flowers; A. umbellata, 8 in., silvery leaves and white flowers; and A. Clavennae, 6 in., with silvery leaves and pure white flowers.
Aconitum.—Handsome border plants, the tall stems crowned by racemes of showy hooded flowers. A. Camarum, 3 to 4 ft., has deep purple flowers in August; A. sinense, 1½ to 2 ft., has large dark purple flowers in September; A. variegatum, 3 ft., has the flowers white edged with blue; A. autumnale, 3 ft., has pale blue flowers; A. Anthora, 1 to 2 ft., yellow; and A. japonicum, 2½ ft., deep blue flowers, produced in September and October. A. Wilsoni, a new species from China, 6 ft. high, with bluish-purple flowers.
Adenophora.—Bell-shaped flowers. A. stylosa, 2 ft., pale blue, elegant; A. denticulata, 1½ ft., dark blue; and in A. liliifolia, 1½ ft., pale blue, sweet-scented—all blooming during summer. Light soil.
Adonis.—A. vernalis, 1 ft., has large bright yellow stellate flowers in April. Deep light soil. A. amurensis is a fine Chinese species.
Ajuga.—Free growing, dwarf and showy. A. reptans, 8 in., has creeping runners, which A. genevensis has not; both bear handsome spikes of blue labiate flowers. Ordinary soil.
Allium.—Hardy bulbs of the garlic family, some species of which are ornamental; the inflorescence is umbellate. In A. azureum, 1 to 2 ft., the flowers are deep-blue; in A. Moly, 1 ft., golden yellow; in A. neapolitanum, 1½ ft., white, very handsome; in A. triquetrum, 8 in., white with green central stripes; in A. pedemontanum, 9 in., reddish-violet, very beautiful, the umbels nodding.
Alstroemeria.—Beautiful plants with fleshy tuberous roots, which are the better if not often disturbed. A. aurantiaca, 2 to 3 ft., orange streaked with red, in July and August; A. chilensis, 2 to 3 ft., blood-red, streaked with yellow, affording many varieties. Deep sandy loam or peat. Should be planted at least 6 or 8 in. deep.
Althaea rosea.—The hollyhock is a noble perennial, 6 to 15 ft. high, with flowers of every colour except blue. Requires rich loamy soil and plenty of space.
Alyssum.—Showy rockwork or front row border plants of easy culture in any light soil; the plants should be frequently renewed from cuttings. A. saxatile, with greyish leaves, and deep yellow flowers, produced in April and May, and the dwarfer A. montanum are useful.
Amaryllis.—Noble half-hardy bulbs, for planting near the front wall of a hothouse or greenhouse; the soil must be deep, rich and well drained. A. Belladonna, the Belladonna Lily, 3 ft., has large funnel-shaped flowers in September, of a delicate rose colour. The variety A. blanda has paler flowers, almost white.