Common Name: Pennyroyal

General Information

Mentha pulegium is a herbaceous perennial plant with stems that are usually prostrate, but occasionally erect. The stems root at the nodes, the plant forming a mat of growth usually 10 - 30cm tall[].
The plant has a long history of use as a medicinal herb and is harvested from the wild for local use as a food, medicine and source of materials. It is sometimes cultivated commercially for its essential oil and is often grown in gadens for its many uses[].

Known Hazards

In large quantities this plant, especially in the form of the extracted essential oil, can cause abortions so it should not be used by pregnant women[].

Botanical References

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Range

Central and southern Europe to western Asia - Britain to Portugal, east to the Caucasus and Iran; throughout the Mediterranean region

Habitat

Moist meadows and sandy soils by streams etc[, ].

Properties

Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Perennial
Height	0.40 m
Pollinators	Bees, Lepidoptera, Insects
Cultivation Status	Cultivated, Ornamental, Wild

Cultivation Details

Succeeds in most soils and situations so long as the soil is not too dry[]. Plants are very quickly diminished by dry conditions[]. Prefers a stiff moist soil that is slightly acid[, , , ]. A sunny position is best for production of essential oils, but plants succeed in partial shade.
Pennyroyal is often grown in the herb garden and is also cultivated commercially as a medicinal plant and for its essential oil[, ].
A yield of 14kg of essential oil per hectare is considered good[].
A very variable species, diploid and tetraploid forms are known as well as ecological races with different compositions of the essential oils[]
There are two main forms of this species. One has weak prostrate stems and spreads by rooting where the stems touch the ground, it is only 10cm tall[]. The other is erect, does not spread so freely and grows about 30cm tall, thus making it easier to harvest[]. There is also at least one named form, called 'Dwarf' it is only a few centimetres tall[].
The whole plant a strong spearmint smell.
Members of this genus are rarely if ever troubled by browsing deer[].

Edible Uses

Leaves - raw or cooked[, , ]. Used as a flavouring in salads or cooked foods[]. A spearmint-like flavour, though rather coarser, it is not used very often in Britain[].
A herb tea is made from the fresh or dried leaves[]. For drying, it should be harvested as the plant comes into flower[].

Medicinal

Pennyroyal has been used for centuries in herbal medicine. Its main value is as a digestive tonic where it increases the secretion of digestive juices and relieves flatulence and colic[]. Pennyroyal also powerfully stimulates the uterine muscles and encourages menstruation, thus it should not be prescribed for pregnant women since it can procure abortions, this is especially the case if the essential oil is used[, ].
The herb is antiseptic, antispasmodic, carminative, diaphoretic, emmenagogue, sedative and stimulant[, , , ]. A tea made from the leaves has traditionally been used in the treatment of fevers, headaches, minor respiratory infections, digestive disorders, menstrual complaints and various minor ailments[, , ]. It is occasionally used as a treatment for intestinal worms[].
Externally, an infusion is used to treat itchiness and formication, inflamed skin disorders such as eczema and rheumatic conditions such as gout[].
The leaves are harvested in the summer as the plant comes into flower and are dried for later use[].

The essential oil in the leaves is antiseptic, though it is toxic in large doses[].

The plant is used in homeopathy[].

Agroforestry Uses:

The plant has a low spreading habit and can be used as a ground cover, though it is somewhat sparse in the winter and can be invaded by the more aggressive weeds[].
Mint species are usually good bee and butterfly attractant plants, supplying them with good quality pollen and nectar[]
Mints are usually quite aromatic plants and they make good companions for cabbages and tomatoes, their aromatic nature helping to repel insect pests[], helping to repel cabbage root fly and other burrowing insects[].

Other Uses

An essential oil rich in pulegon is obtained from the whole plant. It is used as a perfume in soaps etc, as a cleanser for fabrics, in the manufacture of synthetic menthol, as an insect repellant etc and is used against insects[, , , ]. and for the preparation of perfume for soaps as well as for synthetical menthol.

The essential oil is an effective inhibitor of hydrochloric acid corrosion when coated over steel[].

The growing or dried plant repels fleas, ants, moths, mice etc[, , , , , ]. Rats and mice intensely dislike the smell of mint. The plant was therefore used in homes as a strewing herb and has also been spread in granaries to keep the rodents off the grain[]. A strong infusion applied to the face will keep gnats away in the summer[].
The aromatic leaves are used as an ingredient of pot-pourri[].

Propagation

Seed - sow spring in a cold frame. Germination is usually fairly quick. Prick out the seedlings into individual pots when they are large enough to handle and plant them out in the summer. Mentha species are very prone to hybridisation and so the seed cannot be relied on to breed true. Even without hybridisation, seedlings will not be uniform and so the content of medicinal oils etc will vary. When growing plants with a particular aroma it is best to propagate them by division[].
Division can be easily carried out at almost any time of the year, though it is probably best done in the spring or autumn to allow the plant to establish more quickly. Virtually any part of the root is capable of growing into a new plant. Larger divisions can be planted out direct into their permanent positions. However, for maximum increase it is possible to divide the roots up into sections no more than 3cm long and pot these up in light shade in a cold frame. They will quickly become established and can be planted out in the summer.