Spear Mint
Scientific name: Mentha spicata L.
Diagnostic features
Plant glabrous to tomentose, usually with characteristic spearmint scent.
Stems erect, to 90cm.
Leaves lanceolate to ovate, sometimes broadly ovate, usually not or slightly rugose, sometimes markedly so, usually with sharp, forwardly-directed teeth, sessile or ± so.
Upper whorls in axils of small bracts, congested to form narrow, long, not or little-branched, spike-like head.
Calyx bell-shaped, with narrowly triangular to subulate teeth, 1-3mm.
Corolla white to pink or lilac.
Chromosome number: 2n=36, 48.
Habitat
Introduced-naturalized; much grown and naturalized in rough and waste ground.
Distribution
Scattered throughout most of British Isles; ?garden origin.
This species is keyed out on Page 3118 in the Text Key.
Notes I
This species belongs to the Mentha spicata group, involving Mentha spicata (tetraploid), Mentha suaveolens (diploid) and their hybrids with each other and with the non-British Mentha longifolia (diploid), are particularly difficult, especially owing to the great variation of Mentha spicata, which is itself derived from Mentha longifolia x Mentha suaveolens. The 2 triploid hybrids are sterile, but the diploid hybrid and the species are fertile in bisexual plants or in female plants open to a pollen source. Pubescent plants that are not Mentha suaveolens are often impossible to name for certain. Characters of Mentha suaveolens often seen in its hybrids are the broad, obtuse, very rugose leaves with teeth partly folded under the margin and with patchy or clumped indumentum on lowerside; of Mentha longifolia are the lanceolate-oblong, acute, flat leaves with sharp patent teeth and with felted grey indumentum; and of Mentha spicata are the lanceolate to ovate, acute, not to slightly rugose leaves with usually forward-directed teeth and relatively coarse pubescence. Mentha spicata is the most variable; very broad-leaved plants, and strongly rugose-leaved plants occur, but this is the only species of the 3 that can be glabrous to sparsely pubescent and the only species that can smell of spearmint. Hybrids (especially Mentha villosa(x)) can be very variable, showing many combinations of characters not always connected by intermediates, but they do not exactly duplicate the combinations shown by any of the species
Notes II
Fertile tetraploid derived from Mentha longifolia x Mentha suaveolens, variously approaching 1 or the other; often almost impossible to distinguish from its hybrids with these 2 species, but the hybrids are sterile triploids.
Pubescent variants have in the past been misidentified as Mentha longifolia (L.) Huds.
Mentha scotica is a pubescent variant from East Scotland with lanceolate, obtuse, shallowly serrate leaves with an unpleasant scent.
A very distinctive glabrous variant with rugose, broadly ovate leaves and a strong spearmint scent occurs in Southwest Britain; it was formerly referred to as glabrous Mentha spicata x Mentha suaveolens.
Hybrids
- See Mentha smithiana(x) R.A. Graham (= Mentha arvensis x Mentha aquatica x Mentha spicata)
- See Mentha gracilis(x) Sole (= Mentha arvensis x Mentha spicata)
- See Mentha piperita(x) L. (= Mentha aquatica x Mentha spicata)
- See Mentha villosonervata(x) Opiz (= Mentha spicata x Mentha longifolia (L.) Huds.)
- See Mentha villosa(x) Huds. (= Mentha spicata x Mentha suaveolens) |
