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.
Dwarf stemless herbs with scaly bulbs, radical ovate or ovate-lanceolate often spotted leaves, and solitary pendulous rather large flowers on a short scape. Perianth composed of 6 free similar erect or reflexed lanceolate segments. Stamens 6. Fruit a 3-celled capsule. About half-a-dozen species are known, natives of north temperate regions in both the Old and New Worlds. The generic name is from the Greek red, the colour of the flowers in the European species.
1. E. Dens-canis. Dog's-tooth Violet. - This is the common European species, an old and very beautiful border plant. It grows about 6 inches high and the foliage is blotched with purple-brown and white. Flowers about 2 inches in diameter, purplish-red, rosy, lilac or white, according to the variety. It blooms in March and April, and may be classed amongst the handsomest of early Spring flowers.
2. E. Americanum. Yellow Adder's-tongue. - A very similar plant with pale yellow flowers, produced in early Spring. The segments of the perianth are spreading, not distinctly reflexed as in the common species. A native of North America.