Purple Dead Nettle
Lamium purpureum

• Flower: Purple irregular flowers, 1/4-1/2" long, lower lip with 2 rounded lobes
• Leaves: opposite, toothed, appear to be overlapping. Upper leaves purplish.
• Size: Flowers 1-1.5" across; plant 2-8" high in bloom
• Habitat: Roadsides and wasteplaces
• Blooms: April-October

Square stemed, as is typical of the Mint family. Although this first appears in early spring, it blooms almost all year, and so it's not really one of the spring ephemerals. The top whorl of leaves—their color and arrangment—are distinguishing characteristics of this species.