Violets (genus Viola) are flowers of the family Violaceae, common in Europe in slightly shaded conditions such as hedgerows. Violets are small perennial plants with large heart-shaped leaves which flower profusely in spring. This genus includes pansies and the smaller spreading plants known as Johnny Jump-ups. There are two wild varieties, the most common having dark blue flowers, and the less common having white flowers - wild violets are not colored violet.
Violets grow readily from seed, and by sucker, and are fairly easy to transplant.
One quirk of the violet is its elusive scent - a major component of the scent is a ketone compound called ionone, which temporarily desensitises the receptors in the nose; sniff all you like, you won't get any more smell from the flower!
Violet flowers are known in modern cooking (especially as decorative elements), but medieval cooking can also use the violet leaf as a herb.