Horsemint, European

Mentha longifolia
A square-stemmed, densely hairy, pungent 1-5' plant. The opposite, sessile, ovate leaves are sharp-toothed and hairy. The small 3/16" flowers are in terminal and leaf axil spikes. The corolla is lavender and the stamens protrude. Blooms July-October in damp waste places, roadsides.