|Figure 82.Peppermint (Mentha piperita)|
Habitat and range.Peppermint is naturalized from Europe and is found in damp places from Nova Scotia to Minnesota and south to Florida and Tennessee. It is largely cultivated, principally in Indiana, Michigan, Oregon, Washington, and California, for the production of peppermint oil.
Description.Peppermint propagates by means of its long, running roots from which are produced smooth, square stems from 1 to 3 feet in height, erect and branching. The leaves are from 1 to 2 inches long, about half as wide, pointed, and with sharply toothed margins. The plant is in flower from July to September. The small purplish blossoms are placed in circles around the stem, forming thick, blunt spikes.
Part used.The leaves and flowering tops, for which there is a reasonably constant demand, collected as soon as the flowers begin to open and carefully dried. The production of peppermint oil by distillation of the cultivated herb is an extensive industry.* The wild form of the plant is not suitable for this purpose, the cultivated plant containing more and better oil.
*This industry is described in the following publication: Seivers, A.F. Peppermint and Spearmint as Farm Crops. U.S. Dept. Agr. Farmers' Bul. 1555, 26 p., illus. 1929.