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 to 3/8 inch long, densely hairy with both glandular and glandless hairs, green or purplish with slightly flaring triangular lobes that are nearly as long as the calyx tube.

Leaves and stem:

Leaves are up to 4 inches long and 1½ inches wide, with serrated edges, a pointed tip and a rounded or somewhat heart-shaped base. The leaf stalk is up to 1/8 inch long, or more typically absent altogether, and the leaf surfaces are covered in short, fine hairs. Attachment is opposite, with a pair of leaves at a right angle to the pair below it. The main stem is square and hairy along the angles and on the stem sides.

Notes:

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. There are 2 varieties of Marsh Hedge Nettle in Minnesota: var. pilosa has longer hairs on the angles than on the stem sides and leaves mostly ¾ to 1½ inches wide; var. homotricha has leaves rarely wider than ¾ inch and stem hairs all about the same length. A third variety, var. palustris, is a European variety not recorded in Minnesota. Hedge Nettles are similar to Germander, (Teucrium canadense) but its flower has a distinctly split upper lip.