This section is from the book "Handbook Of Hardy Trees, Shrubs, And Herbaceous Plants", by W. Botting Hemsley. Also available from Amazon: Handbook of hardy trees, shrubs, and herbaceous plants.
Shrubs or small trees of variable habit and foliage. Buds clothed with scales. Calyx-lobes valvate. Corolla ovate or campanulate, deciduous. Stamens 10; anthers with or without awns. Capsule 5-celled, dehiscing through the cells. This genus as here limited includes a considerable number of species inhabiting Europe, Asia, and North America. But it has been subdivided into several genera, including the names Cassiopea, Cassandra, Leucothde, etc.
1. A. polifolia. - This is an indigenous species, and the only one of the genus according to some botanists. It is a procumbent shrub with small lanceolate acute coriaceous shining leaves having the margins recurved and glaucous beneath. Flowers small, globose, umbellate, pink or white, produced all the Summer. A widely distributed species varying considerably in its foliage and flowers. A. Canadensis, A. rotundifolia, A. rubra, A. rosmarinifolia, etc., are American varieties.
2. A. tetragona. - A beautiful little shrub about 6 inches high. Leaves scale-like, imbricated, and closely appressed to the branches. Flowers pendulous, globular, white, appearing in April. A native of Lapland.
3. A. Mariana. - A dwarf branching shrub about a yard high. Leaves oval. Flowers white, in pendent clusters from the old wood. Corolla tubular; calyx brown. A native of North America, flowering in Summer.
4. A. calyculata. - An undershrub about 18 inches high with lanceolate or elliptical leaves and urceolate white or pinkish flowers produced in great abundance in the axils of the upper leaves. The specific name refers to the two small bracts at the base of the calyx. A native of Newfoundland, flowering in Spring.
A. speciosa, axillaris, salicifolia, and multiflora are the names of other species rarely seen in gardens.