From Wikipedia, the free encyclopedia: Violets (Viola) are a genus of flowering plants in the family Violaceae, with around 400-500 species throughout the world, mainly in the temperate Northern Hemisphere but also in Hawaii, Australasia, and the Andes in South America. They are typically found in moist and slightly shaded conditions such as hedgerows. Most violets are small perennial plants, but a few are annual plants and some are small shrubs. They typically have heart-shaped leaves, and asymmetrical flowers with four upswept or fan-shaped petals, two each side, and one broad, lobed lower petal pointing downward. The shape of the petals defines many species, for example, some violets have a "spur" on the end of each petal. Flower colours vary in the genus; many are violet as their name suggests, and some are blue, some yellow, some white, some cream; some are bicolored, often blue and yellow. Flowering is often profuse, and may last for much of the spring and summer. One quirk of some violets is the elusive scent of their flowers; along with terpenes, a major component of the scent is a ketone compound called ionone, which temporarily desensitises the receptors in the nose; this prevents any further scent from being detected from the flower.