1. Mentha, Linn.

Strong-scented perennial herbs; rootstock creeping, stoloniferous. Leaves opposite. Flowers small, often axillary and solitary in the New Zealand species, but in others frequently arranged in many-flowered whorls or clusters, which are often aggregated into terminal page 568 spikes. Calyx campanulate or tubular, 5-toothed, throat naked or villous. Corolla-tube short, not exceeding the calyx; limb 4-lobed; lobes nearly equal or the upper one broader. Stamens 4, equal, erect, distant; filaments glabrous; anther-cells 2, parallel. Style shortly bifid. Nutlets dry, ovoid, smooth, not bordered.

A widely spread genus, most abundant in Europe and northern Asia, where the species are highly variable and difficult of discrimination. The single New Zealand species is found nowhere else. Several of the European species have established themselves as weeds or garden-escapes, especially the pennyroyal (M. pulegium), corn-mint (M. arvensis), peppermint (M. piperita), and spearmint ( M. viridis). Descriptions of these will be found in any English Flora.