Mentha longifolia (Horse Mint; syn. M. spicata var. longifolia L., M. sylvestris L., M. tomentosa D'Urv, M. incana Willd.) is a species in the genus Mentha (mint) native to Europe, western and central Asia (east to Nepal and the far west of China), and northern and southern (but not tropical) Africa. 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 tall. The leaves are oblong-elliptical to lanceolate, 5–10 cm long and 1.5–3 cm 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.