Violets are ...

Purple flowers and bright green leaves are the colors of spring.  Bluets, irises and particularly violets against a green background shout springtime.  Bees are the main pollinators of violets and because the bee visual system is tuned to the ultraviolet and blue part of the spectrum, violets are bee magnets.  A group of large colorful butterflies, the fritillaries, has a different relationship with violets. Fritillaries lay their eggs on violets and their caterpillars develop there, but the adults sip nectar from other flowers. 

A patch of Purple Violet (Viola sororia)
in our lawn, Salisbury, NC

Great Spangled Fritillary (Speyeria cybele) in Rowan County, NC.  This
dramatic butterfly develops on violets.  Here it is feeding on Lantana camara.

Violets are in the genus Viola and have a worldwide distribution with most species found in the temperate regions of the northern hemisphere.  North America boasts about 80 species of violets and while many have flowers with the typical purple color, some species produce blue, white or even yellow flowers.

A unique feature of violets is they make two types of flowers.  One is the large, colorful flower, pollinated by insects we associate with violets.  Botanists term these flower chasmogamous.  The second type of flower violets make are small, they never open, lack petals and self-pollinate.  These small flowers are called cleistogamous.   Chasmogamous and cleistogamous are impressive words derived from Greek.  Chasmogamous means open reproduction.  They are bee pollinated and increase genetic diversity by outcrossing.  Cleistogamous is closed reproduction where the small, closed flowers do not host bees and only pollinate themselves.  This type of reproduction does not increase genetic diversity but is highly efficient.  The cleistogamous flowers produce many more seeds than the chasmogamous. 

Viola sororia showing rhizome with roots, leaves and
both chasmogamous and cleistogamous flowers. 

A common violet in the Southeast is Viola sororia, the Purple Violet.  This plant is a perennial and goes by a number of common names; Meadow Violet, Blue Violet, and most interestingly Lesbian Violet.  This last common name came from the ancient Greek poet Sappho of Lesbos who described her lover wearing violets in her hair.   The Purple Violet makes chasmogamous flowers that are about an inch and a half across and range in color from purple to white.   Purple Violets have an underground stem, the rhizome, that produces the heart shaped leaves, flowers and roots.  The colored, chasmogamous flowers are on long stalks and rise above the level of the leaves.  The closed cleistogamous flowers are pale green and are at ground level or sometimes underground.   Viola sororia readily hybridizes with other species of violets and a number of hybrid forms are recognized.  Purple Violet is a weedy plant and we have large stands in our yard that we do not mow and just enjoy the color.

Closeup view of a Viola sororia chasmogamous flower. 
The purple color attracts its bee pollinators.  

A cleistogamous flower of V. sororia.  These flowers are small, green, close
to ground level and self-pollinated.  

Another view of V. sororia cleistogamous flowers.   

Another common, weedy violet is Viola bicolor, the Field Pansy.  This annual is also a lawn denizen, at least in lawns that are not grass monocultures.  Field Pansy is a small plant with dissected leaves and flowers that range from white to blue.  The flowers have small blue lines and often a yellow center. 

A chasmogamous flower of Viola bicolor.  The purple stripes
on the flower directs insect pollinators to the nectar and pollen.  

Violets have a long history in traditional medicine.  They have been used to treat insomnia, respiratory problems and as an emetic.  I have not used violets to treat medical conditions but enjoy them as the color of spring.