Mentha ×piperita (leaf)

Introduction

Introduction from Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Mentha_piperita, retrieved 02/27/2012).

Peppermint (Mentha × piperita, also known as M. balsamea Willd.) is a hybrid mint, a cross between watermint and spearmint. The plant, indigenous to Europe, is now widespread in cultivation throughout all regions of the world. It is found wild occasionally with its parent species.

Peppermint was first described in 1753 by Carolus Linnaeus from specimens that had been collected in England; he treated it as a species, but it is now universally agreed to be a hybrid.

It is a herbaceous rhizomatous perennial plant growing to 30–90 cm (12–35 in) tall, with smooth stems, square in cross section. The rhizomes are wide-spreading, fleshy, and bare fibrous roots. The leaves are from 4–9 cm (1.6–3.5 in) long and 1.5–4 cm (0.59–1.6 in) cm broad, dark green with reddish veins, and with an acute apex and coarsely toothed margins. The leaves and stems are usually slightly hairy. The flowers are purple, 6–8 mm (0.24–0.31 in) long, with a four-lobed corolla about 5 mm (0.20 in) diameter; they are produced in whorls (verticillasters) around the stem, forming thick, blunt spikes. Flowering is from mid to late summer. The chromosome number is variable, with 2n counts of 66, 72, 84, and 120 recorded.

Peppermint typically occurs in moist habitats, including stream sides and drainage ditches. Being a hybrid, it is usually sterile, producing no seeds and reproducing only vegetatively, spreading by its rhizomes. If placed, it can grow anywhere, with a few exceptions.

Peppermint generally grows best in moist, shaded locations, and expands by underground stolons. Young shoots are taken from old stocks and dibbled into the ground about 1.5 feet apart. They grow quickly and cover the ground with runners if it is permanently moist. For the home gardener, it is often grown in containers to restrict rapid spreading. It grows best with a good supply of water, without being water-logged, and planted in areas with part-sun to shade.

The leaves and flowering tops are used; they are collected as soon as the flowers begin to open and can be dried. The wild form of the plant is less suitable for this purpose, with cultivated plants having been selected for more and better oil content. They may be allowed to lie and wilt a little before distillation, or they may be taken directly to the still.

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Macroscopic Entries

Peppermint Botanical Voucher Specimen - Alkemists Laboratories Source: Botanical Voucher Specimen Library, Alkemists Laboratories Peppermint Botanical Voucher Specimen - Alkemists Laboratories

Microscopic Entries

Peppermint (leaf) (Mentha piperita) L., Labiatae.Leaves with stomata above and below, few above; vertical walls thin, wavy. Large, long, rather thick-walled, three to seven celled simple trichromes with short linear to warty cuticular thickenings. Large bladdery glandular trichromes with six to eight secreting cells. Small secreting trichromes with a single terminal secreting cell. Besides this there is present stem tissue, as epidermis, collenchyma, parenchyma, tracheids and ducts. Source: Schneider, A. (1921) The Microanalysis of Powdered Vegetable Drugs, 2nd ed.