Bugleweed

"This plant is often used as medicinal and ornamental plant. It is invasive in parts of North America." "The bugle has dark green leaves with purple highlights. It is a spreading ground cover that grows in a dense mat. The leaves grow 5-8 cm (2-3 in) high but in the spring it sends up 10-15 cm (4-6 in) tall flower stalks with many purple flowers on them." --Wikipedia