Horse Mint

It is a very variable herbaceous perennial plant with a peppermint-scented aroma. Like many mints, it has a creeping rhizome, with erect to creeping stems 40–120 cm (16–47 in) tall. The leaves are oblong-elliptical to lanceolate, 5–10 cm (2.0–3.9 in) long and 1.5–3 cm (0.6–1.2 in) broad, thinly to densely tomentose, green to greyish-green above and white below. The flowers are 3–5 mm long, lilac, purplish, or white, produced in dense clusters (verticillasters) on tall, branched, tapering spikes; flowering in mid to late summer. It spreads via rhizomes to form clonal colonies.

Nicholas Culpeper's Complete Herbal (1653) states that "It is good for wind and colic in the stomach ... The juice, laid on warm, helps the King's evil or kernels in the throat ... The decoction or distilled water helps a stinking breath, proceeding from corruption of the teeth, and snuffed up the nose, purges the head. It helps the scurf or dandruff of the head used with vinegar." Additionally, M. longifolia, like other Mentha species, may have medicinal properties.

Like almost all mints, Mentha longifolia can be invasive. Care needs to be taken when planting it in non-controlled areas.