Monographs Details: Mentha x piperita L.
Authority: Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Description:Species Description - Sterile hybrid of nos. 4 [Mentha aquatica L.] and 7 [Mentha spicata L.]; rhizomatous and often also stoloniferous, 3–10 dm, glabrous or glandular, or the lvs often hirsute along the main veins beneath; main lvs ovate or lance-ovate to elliptic, serrate, acute to occasionally obtuse, 3–6 × 1.5–3 cm, on petioles 4–15 mm; fls crowded in dense terminal spikes (sometimes interrupted below) 2–7 cm long and 1–1.5 cm thick at anthesis; cal 3–4 mm, the lobes hispid-ciliate, the tube without hairs; cor 3.5–5 mm; 2n=66, 72. European cultigen, now widely but rather sparingly established in moist low ground in our range and elsewhere in the U.S.