This section is from the book "Commercial Gardening Vol2", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
A fine genus of bulbous plants, all natives of North America, except the well-known European species, E. Dens-canis, the Dog's Tooth Violet. They flourish in well-drained sandy soil, but in partially shaded and sheltered spots. The flowers, more or less drooping on long stalks, stand well above the leaves, which in many species are beautifully marbled with bronzy green and white. The chief trade is done in the bulbs in autumn, but some species are still very rare. The following kinds are in cultivation: E. albidum, white; americanum, golden yellow, tinted with purple; californicum, creamy white; citrinum, lemon yellow; Dens-canis, rose purple; giganteum, pure white; grandiflorum, bright golden yellow; Hartwegi, creamy white to yellow; Hendersoni, rose purple; Howelli, pale yellow; Johnsoni, rose pink; mesochoreum, white; mon-tanum, cream to pure white; Nuttallianum, golden yellow; propullans, rose purple; purparascens, pale yellow tinted purple; and revolution, pink to deep purple, with several varieties. They all flower between February and May, and are excellent for pot culture in cold greenhouses. Propagation, chiefly by offsets from the older bulbs, may be practised after the foliage has died down each year.