From The Collaborative International Dictionary of English v.0.48 :
Periwinkle \Per"i*win`kle\, n. [OE. pervenke, AS. pervince, fr.
L. pervinca.] (Bot.)
A trailing herb of the genus Vinca.
[1913 Webster]
Note: The common perwinkle ({Vinca minor) has opposite
evergreen leaves and solitary blue or white flowers in
their axils. In America it is often miscalled myrtle.
See under Myrtle.
[1913 Webster]
From WordNet (r) 3.0 (2006) :
Vinca minor
n 1: widely cultivated as a groundcover for its dark green shiny
leaves and usually blue-violet flowers [syn: myrtle,
Vinca minor]