Mentha spicata L., Spear Mint

Account Summary

Growth form and preferred habitats

Mints are undoubtedly the best known culinary crop plants to the public of Britain and Ireland. These culinary favourites are a mixture of archaeophytes, such as this species, and neophytes, such as Apple Mint (M. × villosa), Peppermint (M. × piperita) and Eau de Cologne Mint (M. × piperata var. citrata) (Stace & Crawley 2015). Spear Mint, sometimes referred to as 'Common Spear Mint', is a rather stout, scented, almost glabrous perennial with branched flowering stems, 20-40 cm tall, produced during August and September, growing from an extensively creeping and branching rhizome. Its lanceolate, acute, glabrous leaves have sharply toothed margins, unwrinkled surfaces and are sessile or sub-sessile. The leaves are also opposite, oblong or oblong-lanceolate, rounded (almost cordate) at the base, triangular pointed and are at first spreading, soon becoming decurved. The inflorescence is a long, slender, somewhat interrupted, catkin-like spike, of closely arranged whorls of 3 mm diameter, blue-lilac flowers. These spikes are often arranged into a loose panicle, either continuous or slightly interrupted with occasionally a small lateral spike at the base (Butcher 1961; Hutchinson 1972).

M. spicata grows in lowland areas in a variety of damp to wet places, often in ditches, river banks, on rough or waste ground near habitation. Unfortunately, it also occurs in places where garden rubbish is fly-tipped (K. Walker, in: Preston et al. 2002).

Garden mints of all types, possess vigorous, or even rampant, rhizomatous rootstocks and, in the case of M. spicata, the plant is fertile and sets seed. Thus, with both seed and vigorous vegetative reproduction, they tend to quite rapidly outgrow their allocated garden plot. Reflecting this reproductive ability and vigorous growth, the established strategy of M. spicata is categorised as C/CR, meaning it is intermediate between a Competitor and a Competitive Ruderal (Grime et al. 1988, 2007). Gardeners are often recommended to grow mint species or hybrids in buckets or in sunken containers, rather than in beds in open ground to prevent or restrict the invasive spread of the plants. This spreading property leads to garden mint plants frequently being divided and portions donated to friends or dumped, and hence the propensity of various mints to appear on waste ground or tips near habitation in towns and villages, where, as in this instance, they can easily become naturalised and may prove long persistent (Crawley 2005).

Hybrid origin

The exact origin of M. spicata is unknown, but it is an archaeophyte and is believed to have arisen in cultivation, possibly in C or S Europe (Grieve 1931; Garrard & Streeter 1983). Grieve (1931) suggests it came from the Mediterranean basin and that it was introduced to Britain by the Romans who were great promoters of the species. It also appears to be of hybrid origin, probably derived from a cross between the diploids M. suaveolens (Round-leaved Mint) 2n=24 and M. longifolia (Long-leaved Mint) 2n=24, followed by chromosome doubling. Evidence comes from morphological, cytological and chemical data (Harley 1963; Hendriks 1974). The tetraploid result of this speciation process (2n=48) is a segmental allopolyploid that occasionally segregates parental characters in it progeny, giving rise to the morphological identification difficulties in separating M. spicata from its hybrids (R.M. Harley, in: Stace et al. 2015).

Fermanagh occurrence

Spear Mint is a commonly grown garden plant and it is therefore a little surprising that it was first found outside gardens in Fermanagh as late as 1953, naturalised on waste ground below the old workhouse in Enniskillen. A second find was made by RHN in July 2001 beside a farm track in a remote part of the Western Plateau and the third, and only other station, was discovered by I. McNeill near the Lough Erne Yacht Club, Goblusk Bay, Lower Lough Erne, in October 2002. At the latter site, RHN observed a large patch of this mint covering an area 10 m × 10 m near the bridge on the lane to the Club on 10 September 2010.

It is peculiar that there are no other Fermanagh records for Spear Mint, which is such a widely grown rhizomatous perennial, easily identified by its familiar and distinctive aroma when bruised.

Irish occurrence

In comparison with the Fermanagh situation, the editors of the FNEI 3 account regarded this mint as a casual in the three most north-eastern Irish VCs. They catalogued very few records for Co Down (H38) and Co Antrim (H39) and none at all for Co Londonderry (H40). The Cen Cat Fl Ir 2 lists 16 Irish VCs in which Spear Mint has been previously recorded and the Cat Alien Pl Ir adds a further seven VCs to this listing (not including Fermanagh, H33). The current author (RSF) reckons that this leaves 16 Irish VCs out of the 40 total where M. spicata has never been recorded at all.

The New Atlas hectad map shows M. spicata is extremely thinly scattered across Ireland and not at all concentrated on the larger conurbations as one might expect (New Atlas). With regard to areas of human population density, the Urban Flora of Belfast records Spear Mint in seven 1-km squares in the W of the city, while in Co Dublin (H21), the Flora of Co Dublin listed six post-1984 records for the species in five of their eight flora districts, four of which are coastal.

British occurrence

M. spicata is very widely cultivated as a pot or plot herb for the kitchen and often outgrows its welcome in a garden setting and is sufficiently vigorous to be able to thrive and become naturalised in the wild when it escapes or is discarded; it is not surprising that it is very commonly recorded in suitable lowland situations throughout Britain, from the Channel Isles to Orkney and Shetland (New Atlas). It is, however, very variable (especially with regard to degree of hairiness) and is very difficult to distinguished from its hybrids with other mints (Crawley 2005). Another problem is that hybrids involving M. spicata as one of the parent species, nearly all possess the characteristic spearmint scent (R.M. Harley, in: Stace et al. 2015). Thus it is very possible for identification errors to occur and M. spicata is probably over-recorded to some unknown extent.

European and world occurrence

M. spicata is also widely naturalised in W, E & S Europe and is introduced in S Africa, N America, S Australia and New Zealand (Hultén & Fries 1986, Map 1618). Being of garden cultivated origin, it is probably true to say that it is not indigenous anywhere, although some authors suggest it comes from the Mediterranean or the mountains of C Europe (eg Grigson 1974).

Uses

M. spicata is mostly used for culinary purposes and was greatly appreciated by the Romans. Pliny (according to Gerard (1597)) said of it, "The smell of Mint does stir up the minde and the taste to a greedy desire of meate." Ancient Greeks and Romans believed mint (Spear Mint) would prevent milk coagulating and its acid fermentation. They also used it to perfume rooms, baths and as a restorative like smelling salts are used today. Gerard (1597) considered it, "good against watering eies and all manner of breaking out on the head and sores. It is applied with salt to the bitings of mad dogs." It was also believed good for treating wasp and bee stings. Culpeper (1653) lists 40 maladies for which he thinks mint is, "particularly good".

Spear Mint has been used for whitening teeth and its distilled oil is still used to flavour toothpaste and chewing gum and to perfume soap. A strong decoction is said to cure chapped hands (Grieve 1931).

The properties of Spear Mint oil are similar to those of Peppermint, being stimulant, carminative and antispasmodic. Its effects are, however, less powerful and it is less used than Peppermint although it is better adapted for use on children's maladies. Its taste is more pleasant and less strong than Peppermint (Grieve 1931).

Names

Turner (1566) referred to garden mint of his time as 'Spere Mynte'. He ascribes the name on account of the leaf shape, not the spiked inflorescence. This accords with the 16th century botanists' Latin name of the plant 'mentha angustifolia spicata', 'narrow-leaved spiked mint' and 'mentha acuta', 'sharp-pointed mint' (Grigson 1974). However, the Latin specific epithet 'spicata' does refer to an elongated inflorescence of sessile flowers, ie 'a spike' (Gledhill 1985).

Under the synonym M. viridis (L.) L. (R.M. Harley, in Tutin et al. 1972), there are five English common names listed by Britten & Holland (1886), given as

'Brown Mint' (Gerard 1597); 'Garden Mint' (Lyte 1578); 'Mackarel Mint' (Gerard 1597); 'Our Lady's Mint' (Gerard 1597) and 'Spearmint'.

Threats

None.

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