Table 2.
Characteristic features of some of the main Mentha species (Fig. 1)
| Mentha species | Morphology |
|---|---|
| Mentha arvensis L. | Stem: Erect–ascending branched stem ( 19 , 20 ) |
| Leaves: Arranged in opposite pairs, sparsely hairy, shortly petiole or sessile, oblong-ovate or lanceolate in shape and shiny dark green in color, serrated margins ( 19 , 20 , 32) | |
| Flowers: Mauve in color, occur in whorls and borne on leaf axils ( 20 , 32 ) | |
| Mentha spicata L. | Stem: Square-shaped and may be hairless or hairy ( 33 ) |
| Rhizome: Wide-spreading and creeping underground rhizome | |
| Leaves: Arranged in opposite pairs, ovate to lanceolate in shape and light green in color, often hairless on both sides, serrated margins ( 20 ) | |
| Flowers: Pink or white in color, arranged in a spike inflorescence ( 20 ) | |
| Mentha longifolia (L.) Huds. | Stems: Whitish and branched stems, the stems are erect to creeping 0.5–1 m tall and covered with short and soft hairs |
| Rhizome: Creeping rhizome ( 19 ) | |
| Leaves: The leaves are covered by whitish long hairs, oblong-elliptical to lanceolate in shape with toothed margins and green to greyish-green in color ( 19 , 20 , 33) | |
| Flowers: White to mauve in color, densely arranged into tapering spikes ( 20 , 33 ) | |
| Mentha aquatica L. | Stems: Square-shaped in cross-section, green or purple in color and hairy to almost hairless ( 19 , 33 ) |
| Rhizome: Wide-spreading rhizomes with fibrous roots | |
| Leaves: Opposite, finely toothed, ovate to ovate-lanceolate in shape, green and sometimes purplish in color, hairy to almost hairless | |
| Flowers: The flowers are very small, densely crowded and the inflorescences are near-spherical, pinkish to purple in color ( 19 , 33 ) | |
| Mentha suaveolens Ehrh. | Stems: Erect, square-shaped stems with short internodes, sparsely hairy ( 34 ) |
| Leaves: Opposite, toothed margins, shortly petiole or sessile, ovate-oblong to suborbicular in shape and bright green in color, the leaves are wrinkled with sunken venation and hairy above ( 34 ) | |
| Flowers: Tubular flowers arranged on spike inflorescence and their color is white, pinkish or violet ( 34 ) | |
| Mentha piperita | Stems: Four-angled, purplish, branching towards the top, slightly hairy |
| Leaves: Opposite, petiolate, sharply seriate, pointed, dark green color | |
| Flowers: Purple, small, four-lobed corolla (20-mint/peppermint p.pushpangadan,S.K. Tewari handbook of herbs and spices) | |
| M. Mozaffarianii Jamzad | Stems: Quadrangular, epidermis covered of hairs |
| Leaves: Leaf surface covered of hairs ( 21 , 35 ) |