This is "peppermint"--the most widely naturalized plant in the genus. Menthol content is higher in this variable hybrid (2n = 72, 84, 108) than in either of its parents: aquatica (2n = 96) and spicata (2n = 48). Plants are reportedly sterile, but some fertility may be expected in Mentha hybrids (Tucker & Naczi 2007). Occasional plants are more hairy, and can appear spontaneously due to somatic mutation. M. piperita is often confused with spicata, but has generally longer petioles on mid-cauline leaves (4-15 mm versus 0-3 mm), more reddish hues in foliage and flowers, and distinctive flavor (mostly menthol and menthone versus carvone).