Flower:

Flowers are whorled around the stem, usually in groups of 6, in a spike-like cluster at the top of the stem and at the end of branches arising from leaf axils in the upper plant. Individual flowers are ½ to ¾ inch long and irregular; the outside of the upper lip is covered in short hairs, and the lower lip is lobed in 3 parts. Color is pink to lavender with white and darker purplish spots on the inside of the lower lip. There are 4 dark purple stamens under the upper lip. The calyx holding the flower is ¼ inch long or less, hairy with non-glandular hairs, and has slightly flaring triangular lobes that are at least half as long as the calyx tube.

Leaves and stems:

Leaves are up to 6 inches long and 2½ inches wide, with serrated edges, a pointed tip and a rounded or somewhat heart-shaped base. The leaf stalk is up to 3/8 inch long, or sometimes absent altogether, and the upper leaf surface is covered in short hairs. Attachment is opposite, with a pair of leaves at a right angle to the pair below it.

The main stem is green, square and has stiff downward pointing hairs along the angles but is smooth on the stem sides.

Notes:

Hairy Hedge Nettle also goes by Latin names Stachys tenuifolia var. hispida and S. palustris var. hispida, but the accepted name in Minnesota is S. hispida. There are 3 species of Stachys in Minnesota; distinguishing features are the length of the leaf stalk and the hairiness of various parts, as well as more subtle differences in the calyx. Some references state S. palustris has white spots on the flowers and other species have purple spots, but I have not found this to be a consistent truth; both white and purple spots to some degree are common on all. Marsh Hedge Nettle, the most common Stachys species in Minnesota, has mostly stalkless leaves and stems with hairs on the surface as well as the angles. Hairy Hedge Nettle (Stachys hispida) has hairs only along the angles, is more roughly hairy, and has mostly short-stalked leaves. Smooth Hedge Nettle (Stachys tenuifolia) is mostly hairless throughout. Hedge Nettles are similar to Germander, (Teucrium canadense) but its flower has a distinctly split upper lip.