Mentha arvensis L.

Perennial with hairy stems, to c. 50 cm tall, usually much-branched. Lvs shortly petiolate; lamina 2.5–5 × 0.7–2.5 cm, lanceolate, ovate or elliptic, not rugose, serrate or crenate-serrate, hairy, sometimes minutely so, dotted with oil glands; lamina of uppermost lvs smaller; base cuneate, apex ± subacute. Verticels of many fls, in distant axillary whorls; pedicels short. Calyx 3–3.5 mm long, campanulate, hairy and with oil globules outside, glabrous inside; teeth equal, much < tube at anthesis, acuminate. Corolla 5–6 mm long, hairy outside, mauve, exserted. Stamens usually exserted from corolla, sometimes scarcely exceeding calyx. Nutlets 8–9 mm long, oblong, minutely reticulate.

[From: Webb et al. (1988) Flora of New Zealand. Volume 4.]

Flowering: Dec.–Feb.