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.
Bulbous herbs with flat or terete radical leaves and capitate or umbellate flowers enclosed in a membranous spathe at the summit of a slender naked or leafy scape. Perianth-segments free, spreading or campanulate. Stamens equal in number, and on the bases of the perianth-segments. Gapsule membranous, with one or two seeds in each of the three cells. The Latin name for A. sativum, the Garlic. This is a large genus, including, besides the Onion and its useful congeners, several very ornamental and less foetid species. Natives of the northern temperate regions of the Old and New Worlds.
2. A. roseum. - A smaller plant with narrow lanceolate leaves and a leafy scape about a foot high bearing a large umbel of rosy-purple flowers in June.
There are several other species in cultivation, such as A. odorum, with white; A. azureum, deep blue; A. suaveolens, purple; and A.flavum, yellow flowers.