Spearmint
Spearmint, also known as garden mint, common mint, lamb mint and mackerel mint, is native to Europe and southern temperate Asia, extending from Ireland in the west to southern China in the east. It is naturalized in many other temperate parts of the world, including northern and southern Africa, North America, and South America. It is used as a flavouring in food and herbal teas. The aromatic oil, called oil of spearmint, is also used as a flavoring and sometimes as a scent.
The species and its subspecies have many synonyms, including Mentha crispa, Mentha crispata, and Mentha viridis.
Description
Spearmint is a perennial herbaceous plant. It is tall, with variably hairless to hairy stems and foliage, and a wide-spreading fleshy underground rhizome from which it grows. The leaves are long and broad, with a serrated margin. The stem is square-shaped, a defining characteristic of the mint family of herbs. Spearmint produces flowers in slender spikes, each flower pink or white in colour, long and broad. Spearmint flowers in the summer, and has relatively large seeds, which measure. The nameMentha spicata varies considerably in leaf blade dimensions, the prominence of leaf veins, and pubescence.
Taxonomy
Mentha spicata was first described scientifically by Carl Linnaeus in 1753. The epithet spicata means 'bearing a spike'. The species has two accepted subspecies, each of which has acquired a large number of synonyms:- Mentha spicata subsp. condensata Greuter & Burdet – eastern Mediterranean, from Italy to Egypt
- Mentha spicata subsp. spicata – distribution as for the species as a whole
Origin
Hybrids
Mentha spicata hybridizes with other Mentha species, forming hybrids such as:- Mentha × piperita, black peppermint, hairy peppermint
- Mentha × gracilis, Scotch spearmint
- Mentha × ''villosa''
Varieties and cultivars
- M. spicata var. crispa – with very crinkled leaves.
- M. spicata var. crispa 'Moroccan' – with crinkled leaves and white flowers.
- M. spicata 'Tashkent' – with slightly crinkled leaves.
- M. spicata 'Spanish' – with mauve-pink flowers.
History and domestication
Spearmint is documented as being an important cash crop in Connecticut during the period of the American Revolution, at which time mint tea was noted as being a popular drink due to it not being taxed.
Ecology
Spearmint can readily adapt to grow in various types of soil. Spearmint tends to thrive with plenty of organic material in full sun to part shade. The plant is also known to be found in moist habitats such as swamps or creeks, where the soil is sand or clay.Spearmint ideally thrives in soils that are deep, well-drained, moist, rich in nutrients and organic matter, and have a crumbly texture. The pH range should be between 6.0 and 7.5.
Diseases and pests
Fungal diseases
Fungal diseases are common diseases in spearmint. Two main diseases are rust and leaf spot. Puccinia menthae is a fungus that causes the disease called "rust". Rust affects the leaves of spearmint by producing pustules inducing the leaves to fall off. Leaf spot is a fungal disease that occurs when Alternaria alernata is present on the spearmint leaves. The infection looks like circular dark spot on the top side of the leaf. Other fungi that cause disease in spearmint are Rhizoctonia solani, Verticillium dahliae, Phoma strasseri, and Erysiphe cischoracearum.Nematode diseases
Some nematode diseases in spearmint include root knot and root lesions. Nematode species that cause root knots in this plant are various Meloidogyne species. The other nematode species are Pratylenchus which cause root lesions.Viral and phytoplasmal diseases
Spearmint can be infected by tobacco ringspot virus. This virus can lead to stunted plant growth and deformation of the leaves in this plant. In China, spearmint have been seen with mosaic symptoms and deformed leaves. This is an indication that the plant can also be infected by the viruses, cucumber mosaic and tomato aspermy.Cultivation and harvest
Spearmint grows well in nearly all temperate climates. Gardeners often grow it in pots or planters due to its invasive, spreading rhizomes.Spearmint leaves can be used fresh, dried, or frozen. The leaves lose their aromatic appeal after the plant flowers. It can be dried by cutting just before, or right as the flowers open, about one-half to three-quarters the way down the stalk. Some dispute exists as to what drying method works best; some prefer different materials and different lighting conditions. The leaves can also be preserved in salt, sugar, sugar syrup, alcohol, or oil.
Oil uses
Spearmint is used for its aromatic oil, called oil of spearmint. The most abundant compound in spearmint oil is R--carvone, which gives spearmint its distinctive smell. Spearmint oil also contains significant amounts of limonene, dihydrocarvone, and 1,8-cineol. Unlike oil of peppermint, oil of spearmint contains minimal amounts of menthol and menthone. It is used as a flavouring for toothpaste and confectionery, and is sometimes added to shampoos and soaps.Traditional medicine
Spearmint has been used in traditional medicine.Insecticide and pesticide
Spearmint essential oil has had success as a larvicide against mosquitoes. Using spearmint as a larvicide would be a greener alternative to synthetic insecticides due to their toxicity and negative effect to the environment.Used as a fumigant, spearmint essential oil is an effective insecticide against adult moths.