Peppermint is a herbaceous perennial plant, growing to 30–90 cm tall from rhizomes. The rhizomes are wide-spreading and fleshy. Leaves are 4–9 cm long, 1.5–4 cm broad, dark green with reddish veins, and with a pointed tip and coarsely toothed margins. Leaves are very much like the mint leaves. The leaves and stems are usually slightly hairy. The flowers are purple, tiny, 6–8 mm long, 4-petalled, about 5 mm across. They are borne in whorls around the stem, forming thick, blunt spikes. Flowering is from mid to late summer. It was first described by Linnaeus from specimens collected in England - he treated it as a species, but it is now universally agreed to be a hybrid. is a hybrid mint, a cross between watermint (Mentha aquatica) and Spearmint (Mentha spicata). Peppermint is sometimes regarded as 'the world's oldest medicine', with archaeological evidence placing its use at least as far back as ten thousand years ago. Peppermint has a high menthol content, and is often used as a flavouring in tea, ice cream, confectionery, chewing gum, and toothpaste. The oil also contains menthone and menthyl esters. It is the oldest and most popular flavour of mint-flavoured confectionery. Peppermint can also be found in some shampoos and soaps, which give the hair a minty scent and produce a cooling sensation on the skin.