This little flower is Vinca minor, the lesser periwinkle. It is native to Central Europe spreading down through Southern Europe into Asia Minor (although at this point it has naturalized throughout the temperate world as an invasive garden plant). In the United States they are sometimes confusingly (mis)called “myrtle”.
Lesser periwinkles are subshrubs (which would have made for a good insult in grade school). They grow only to 40 centimeters (16 inches) high and do not climb—though they spread rapidly into large clonal colonies. Periwinkles are members of the hardy Aster family (the plant family not the snooty otter-killing magnates from New York). With vigorous evergreen leaves and shapely five-petaled flowers, the plants can be used as perennial ground cover for flower gardens.
The best and most famous feature of lesser periwinkles is the distinctive blue-purple color. In English the flower and its color have become synonymous—the latter surpassing the former in popular recognition! Periwinkle is a very lovely and soothing color which seems purple in some light and blue in others. It makes an ideal color for walls and home furnishings as well as garments.