Mentha longifolia

Mentha longifolia
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Eudicots
(unranked):	Asterids
Order:	Lamiales
Family:	Lamiaceae
Genus:	Mentha
Species:	M. longifolia
Binomial name
Mentha longifolia (L.) Huds.

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.^[1][2][3]

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 in mid to late summer. It spreads via rhizomes to form clonal colonies.^[4][3][5]

There are seven subspecies:^[1][2][5]

• Mentha longifolia subsp. longifolia. Europe, northwest Africa.
• Mentha longifolia subsp. capensis (Thunb.) Briq. Southern Africa.
• Mentha longifolia subsp. grisella (Briq.) Briq. Southeastern Europe.
• Mentha longifolia subsp. noeana (Briq.) Briq. Turkey east to Iran.
• Mentha longifolia subsp. polyadena (Briq.) Briq. Southern Africa.
• Mentha longifolia subsp. typhoides (Briq.) Harley. Northeast Africa, southwest Asia.
• Mentha longifolia subsp. wissii (Launert) Codd. Southwestern Africa.

It has been widely confused with tomentose variant plants of Mentha spicata; it can be distinguished from these by the hairs being simple unbranched, in contrast to the branched hairs of M. spicata.^[4]

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

References

1. ^ ^{a b} Euro+Med Plantbase Project: Mentha longifolia
2. ^ ^{a b} African Flowering Plants Database: Mentha longifolia
3. ^ ^{a b} Flora of China: Mentha longifolia
4. ^ ^{a b} Blamey, M. & Grey-Wilson, C. (1989). Flora of Britain and Northern Europe. ISBN 0-340-40170-2
5. ^ ^{a b} Huxley, A., ed. (1992). New RHS Dictionary of Gardening. Macmillan ISBN 0-333-47494-5.

See also

• Menthol
• Pulegone