Pennyroyal (botanical name Mentha pulegium) belongs to the mint species and is a member of the Lamiaceae family. Although this herb is native to Europe and the western regions of Asia, pennyroyal has now been naturalized in North and South America. Several species and a wide variety of pennyroyal, such as apple mint, pineapple mint, orange mint, are found across the globe. This variety of plant flourishes well in proper sunlit areas and partial shade. This variety of plant requires moist, deep and sandy soils for robust development. In addition, pennyroyal plants also need fertile soil and regular watering. Unless the roots of this variety of plants are not restricted by underground fencing, they breed rapidly.
Pennyroyal, which belongs to the Lamiaceae family, is an aromatic perennial plant that develops from bulbs or tubers. The stems of this plant are found in an assortment of forms that range from short to sub- glabrous and bushy, decumbent to clambering, split, four-sided shapes. Generally, pennyroyal plants grow up to a height of four to 35 inches or approximately 10 cm to 90 cm. The leaves of the plant normally grow to a length of 0.25 to 1.0 inch or approximately 1.0 to 2.5 cm and are shortened at the end. At the base, the leaves are petioled and those growing at the elevated levels of the stems are almost sessile. The shape of the leaf blade also varies from slender ovate to elliptic and the base of the leaves either peter out or chunky. The leaves have a rounded end that is completely or somewhat indented. The underneath surface of the pennyroyal leaf is undersized and has bristles. At times, the pennyroyal leaves are also found growing in a group like barb or panicles. When they grow separately, the leaves are supplementary and resembling heads and are somewhat inclined owing to reflexed or minor leaves or bract that resembles leaves.
Pennyroyal grows abundantly in inundated areas during the spring or in locations that are moist in some seasons or throughout the year, such as banks of streams, seeps, marshy lands, ditches, spring pools and swales. Generally, the plant is found growing in dense clay or soil sediments caused by silts. The herb flourishes best on regularly problematic locations, such as meadows that are intensely grazed or places having some sort of disturbances - recurring depositions of sediments and where you will find organic remains. Pennyroyal has the aptitude to withstand somewhat alkalinity, recurring arid periods and muggy climatic conditions. One would find pennyroyal thriving at its best and growing very densely in places where other plants and trees provides shade to its stems and roots. In fact, the shade provided by other trees and plants helps in withholding the moisture in the soil as well as create a moist temperature which is just perfect for the growth of pennyroyal plants.
When leaves of pennyroyal are crushed they emit a very potent scent something akin to that of the spearmint. Traditionally, pennyroyal is a culinary herb and it was used by the Greeks and Romans to add essence to their delicacies. In addition, the herb is a useful and extensively used traditional medication and is especially used to cause abortion (abortifacient). The essential oil obtained from pennyroyal is widely made use of in aromatherapy. The pennyroyal essential oil contains high amounts of pulegone and is an extremely noxious and unsteady organic amalgam that affects the liver and functioning of the uterine system.
In fact, both pennyroyal and spearmint were regarded to be of diverse utility by the primeval herbalists. Similarly, natural historians held these two herbs in high esteem for their remedial properties. In his writings, Pliny (23 AD – 79 AD), the ancient Greek natural historian, described pennyroyal as a first-rate therapeutic perfumed herb compared to roses. He documented that pennyroyal was widely used to purify water. Another natural historian Dioscorides, a contemporary of Pliny, noted that pennyroyal was a very helpful herb for women and said that the plant was useful in provoke menstruation as well as facilitating child birth. Many years later, in 1597, John Gerard documented that people wearing pennyroyal garland as a crown would not only prevent their head from swimming, but were also relieved of all body pains and dizziness.
Additionally, pennyroyal is considered to be an effectual to put off flea invasion and this is evident from the fact that the expression ‘pulegium' has been derived from the Latin word denoting flea.
It is interesting to note that the herb has very unpredictable habits. At times, pennyroyal may be found as a low growing and spread out plant, on other occasions the herb grows vertically as a lean sub-shrub. Pennyroyal produces profoundly pink, violet or blue blooms that are usually present in thick coiled clusters at elevated joints of the plant. While the leaves and the branches of the pennyroyal plant are very commonplace, the stems of the plant have a four-sided shape when cut. The stems usually climb from the tubers or rhizomes. As mentioned earlier, pennyroyal possesses a potent and pungent scent that is similar to mint. Then again, pennyroyal is also different from several mint varieties. Especially, unlike the blooms of several types of mints, the flowers of pennyroyal are slightly bilabiate or two-lipped and not notably two-pronged.
Pennyroyal possesses multiple therapeutic properties and has traditionally been used to treat several disorders since ages. This herb is primarily used for its usefulness to maintain the health of the digestive system. Ingestion of medicinal formulations prepared with pennyroyal functions as a digestive tonic that enhances the secretion of digestive enzymes in the stomach and intestines and alleviates problems like colic and flatulence. In addition, pennyroyal is a potent stimulant of the uterine muscles and induces menstruation. It is important to note that since the herb is effectively used to cause abortions and, hence, it should not be used by pregnant women.
Pennyroyal possesses antispasmodic, carminative (a medication that relieves flatulence), antiseptic, emmenagogue (a medication that induces menstruation), diaphoretic (a medication that causes perspiration), tonic and sedative properties. An herbal tea prepared with the pennyroyal leaves has been customarily used by herbalists to treat medical conditions, such as headaches, fevers, digestive problems, trivial respiratory contagions, menstrual problems and other smaller maladies. At times, the herb is also recommended for flushing out or treating intestinal worms. An infusion prepared with the dried out leaves of the herb is applied topically to heal itchiness, inflamed skin problems like eczema, formication (an unusual feeling as of insects running over or into the skin) and rheumatic conditions like gout. The leaves of this herb are picked during summer before the onset of the plants' flowering season and dehydrated and stored for use afterward. The essential oil obtained from pennyroyal leaves is known to be antiseptic. However, large doses of the essential oil may prove to be noxious or even fatal.
The essential oil extracted from the whole pennyroyal plant is utilized for manufacturing soap as well as a detergent for fabrics. The growth of this plant becomes thin during the winter and it is susceptible to invasion by destructive weeds. Plants that are in growing stage or even dry out plants of pennyroyal are effective in repelling ants, rodents, moths and fleas. In fact, rodents have an extreme aversion to the scent of mints. Hence, it is little surprising that people not only strew the herb in their homes to keep off insects and rodents, but the dried plant parts were also kept in different places in the granaries with a view to protect grains from invasion by mice. Topically applying an infusion prepared with the leaves of pennyroyal on the face is effective in evading insects during the summer season. The infusion is said to be very potent and, hence, effectual in repelling gnats. The fragrant leaves of pennyroyal also form an important element in the manufacture of room fresheners (potpourris) and deodorants.
As far as its role as an effective tonic for the digestive system is considered, pennyroyal resembles peppermint to a great extent. In fact, apart from inducing the secretion of digestive enzymes, this herb all offers relief from conditions, such as stomach aches, colic and flatulence. In addition, herbalists also recommend medical preparations with pennyroyal to treat and flush out intestinal worms. Pennyroyal has additional therapeutic properties too, including its use to treat headaches and minor respiratory infections. Many herbal medicine practitioners also use the herb to lower body temperatures (fevers) and stomach infections. Moreover, pennyroyal is also a useful herb for women. It acts as an inducement for menstrual cycle and also functions as a potent stimulant for the uterine muscles. The preparation with the herb is also applied externally on the skin to alleviate burning sensations, such as eczema. Many herbal physicians also recommend the herb to treat rheumatic conditions or body joint aches, such as gout.
An herbal tea prepared with the dried pennyroyal leaves may be used like an infusion, which is said to be safe if consumed in limited dosages. Herbal medicine practitioners have customarily and successfully used this tea prepared with the herb as an abortifacient (to induce abortions) and an emmenagogue (to stimulate menstruation cycle) since ages. However, it is advisable that women should not use the herbal tea as a self-medication to cause abortion. Incidentally, a young woman died when she attempted a self abortion using the herbal tea prepared with pennyroyal leaves for an unnoticed ectopic pregnancy or extra uterine pregnancy way back in 1994. According to reports, the unfortunate woman had taken excessive dosage of the pennyroyal herbal tea - normally, it is recommended for five days, but she seemed to have taken it for a longer duration. All said and done, currently, the most widespread use of this herbal tea is to treat stomach disorders. Apart from these uses of pennyroyal, other uses of the herb include its use as a treatment for gallbladder diseases, hepatitis, gout, flatulence, fainting and even minor respiratory infections. The herb is also recommended to strengthen the gums. Pulverized pennyroyal leaves are also blended with vinegar to treat tumors.
Other medical uses
As mentioned earlier, pennyroyal was extensively used by the Greeks and Romans as a culinary herb. They added the herb to their delicacies to add essence or aroma. In addition, it was a common custom of the primeval Greeks to use pennyroyal for flavouring their wine. In fact, numerous recipes mentioned in the Roman Apicius cookbook require the use of pennyroyal. The Romans either used only pennyroyal in their cooking or, at times, blended this herb with others, such as oregano, lovage and coriander. While the herb continued to be used by people in the Middle Ages to flavour their delicacies, after some time, its usage became less popular as a cooking herb and presently people seldom use pennyroyal for cooking.
Mint also has industrial utility. Manufacturers of room fresheners and deodorants use the aromatic mint leaves for perfuming the packages of these products. In addition, they are simply used to add scent to packets.
Habitat and cultivation
Pennyroyal is native to Europe as well as the western regions of Asia, but has now been naturalized in several parts of the world and is extensively cultivated in North as well as South America all the year around. Pennyroyal is commercially available in the market in a wide range - apple mint, orange mint and pineapple mint. Pennyroyal grows best in places where there is sunlight and partial shade provided by other trees and plants as this helps the soil on which it is grown to retain moisture. Continuous watering and a rich soil are the basic necessities for this herb to flourish. Unless the roots of the herb are constrained by preparing subversive obstacles or barricades, pennyroyal has an inclination to proliferate at a rapid rate and invade the entire ground where it is grown. It may be repeated again that pennyroyal propagates best in soil that is sandy and also moist having plenty of humus. According to researches, the herb will thrive best in soil conditions that have a pH range varying between 5.5 and 7.0.
Several researches have confirmed that pennyroyal plants thrive well in places receiving complete sunlight or in partial shade provided by the trees growing in the vicinity. In fact, the variety of mint known as water mint has a special aptitude to withstand considerable shade. Then again, another type of mint called the Corsican mint is only able to grow when there is shade. Nevertheless, it has been noticed that the more northwards the mints or pennyroyal are cultivated, the lesser aroma and flavour they exhibit. Hence, people cultivating mints in the more northern locales need to provide sufficient sunlight and water for the herb to thrive well as well as produce the desired aroma and essence.
It is possible to propagate mints from their seeds. Nevertheless, in the case of majority of the mint varieties, it is advisable not to grow them from their seeds as doing so would not produce the desired results - aroma and flavour. Hence, the best way to propagate mints is to use the grafting method. The most suitable time to graft the plants is just before the herb starts producing blooms during spring. In order to propagate mints by grafting, you need to cut the stems of any mature mint plant, segregate the mature plant or, alternately, buy mint plant grafts from any nearby nursery. When new shoots have appeared on the cut stems, plant them in their permanent position outdoors in rows providing a space of about 18 inches or 45 cm between two plants.
After the new mint plants have established themselves in the soil firmly, they begin to spread at a rapid pace both subversively as runners and as stolons above the ground. Thus, if you want to protect your garden of herbs from the aggressive invasion of the mint plants or want to stop them from growing all over the place, it is essential to maintain the plants regularly. Especially, find out the unwanted or surplus runner and get rid of them. This process needs to be undertaken before the onset of the spring. Alternately, you may also construct fences or barricades under the ground to prevent the rapid spread of the mint runners or limit the growth of the herb to a specific area in your garden. You can do this by surrounding the mint plants with under ground plastic dividers having a height of at least 12 inches or 30 cm. You may also limit the unruly growth of the mint plants by creating submerged drainage floors around the plant roots. However, the simplest way to do this is to plant the herb in large containers with proper drainage system and then place the containers under the ground.
In order to grow the best variety of mints, cultivators may follow the tips mentioned here. Squeeze the flowers of the mint as this will enable you to obtain the maximum number of mint leaves, while preventing the rapid growth of the plants under the ground. Tweaking the flowers will prevent the lateral growth of the plants and facilitate them to grow like dense bushes. In addition, it is also important to renew the old and mature mint plants in every three years. You may achieve this by dividing the roots and planting them again in your garden either during the spring or winter.
Although the pennyroyal plants have a preference for and thrive well in fertile sandy soil, they become susceptible to invasion from different types of microorganisms, such as mint flea beetles, aphids, verticillium withering and spider mites when the soil they are cultivated in is very rich. Attacks by such microbes may often result in the withering of the plants. If you encounter such situations in your herbal garden, instantly uproot and burn the affected plants. At the same time, do not plant any new plant at the spot soon after. You may, however, undertake replanting in a different site in the subsequent season. In locations where the winters are extremely unbearable, it is important to provide shelter to the mint plants. In such locations, the plants need to be covered with hay to protect the runners of the plant from any damage due to the adverse or extreme climatic condition. However, remember never to use mud along with the hay to cover the runners for protection from cold.
While mint is usually cultivated outdoors, this herb may also be grown indoors in containers provided you are able to tend them regularly and carefully. In order to grow the mints or pennyroyal plants indoors, you ought to buy commercially available soil for cultivating the plants. Adopt the root division process and place the sliced roots of the herb in the containers filled with the potting soil during the spring or early part of winter. Ensure that the pots or containers are sufficiently spacious to facilitate the healthy growth of the runner roots of the mint plants. Since mint plants thrive best in sunlight, even when you are growing them indoors ensure that you put the pots outdoors for a few hours (at least five hours) every day for the plants to soak in sufficient sunlight. The pots should also have a good drainage system as the mint plants have a preference for moist and not soggy soil. To ensure optimal growth of the plants growing indoors, you may also add liquid plant nourishments to the soil in the pots once in a month or so. If you desire the mint plants to produce highly flavoured leaves, prevent the flowering of the plants. This may be achieved by allowing the potted plants to grow up to a maximum height of five inches (13 cm) only. In case you find the plants withering or their color changing from green to yellowish, make no delay in re-planting them in larger containers. Alternately, you may even uproot and discard the plants after dividing their roots for replanting in the subsequent season and in a different container.
Mint or pennyroyal plants are extremely vulnerable to arid conditions and they wither away when the climatic conditions turn dry. These plants have a preference for soils that are firm, humid and somewhat acidic. As mentioned earlier, the mint plants thrive best and yield the maximum amount of essential oil when grown in sunlit locations. However, they have the aptitude to tolerate and grow well even in partial shade; especially shade provided by vegetation in the neighbourhood enables the soil to retain its moisture. Pennyroyal is not only cultivated in herb gardens for its culinary use, but also cultivated commercially for the therapeutic properties possessed by the herb.
Pennyroyal plants are found in two forms - while one variety has weak horizontal stems and multiplies by developing roots wherever the stems come in contact with the ground and grows up to a height of just around 10 cm, the other variety is erect and grows up to a height of approximately 30 cm. The second type of pennyroyal plants do not multiply as fast as the first variety and it is easier to harvest this form of plants. In fact, there is another variety of pennyroyal known as the ‘Dwarf', which grows up to a height of only a few centimetres. The entire plant of this herb has a potent spearmint aroma and the blooms of this species draw numerous insects, bees and butterflies. Pennyroyal plants provide protection to other vegetations like cabbages and tomatoes when grown in the vicinity by repelling the cabbage root flies and other insects that burrow the earth. It is interesting to note that the browsing deer never or, perhaps, seldom disturb the plants belonging to this genus.
Pennyroyal plants may be propagated by seeds. In this case, the seeds need to be sown during the spring in a cold frame. When the plant is propagated by seeds, new sprouts emerge reasonably quickly. Once the seedlings have grown sufficiently and can be handled, prick them out of the cold frame individually and first plant them in separate containers. When they have developed further, you may plant them in the permanent positions outdoors during summer. It may be noted that the seeds of the Mentha species have a great tendency to hybridize with other varieties of the genus and, hence, it is difficult to depend on them to yield the genuine variety. In fact, even if there is no hybridization of the plants, the seedlings will not grow in a homogenous manner and, therefore, when grown up the amount of therapeutic oils enclosed by the plants will differ greatly. Hence, if you are keen on cultivating the mint plants having a specific fragrance, it is advisable to propagate the species by means of root division. Root division of the pennyroyal plants may be undertaken throughout the year. Nevertheless, it is perhaps best to undertake the root divisions during the spring or autumn as this would enable the plants to settle themselves relatively faster.
It is interesting to note that practically any part of the mint or pennyroyal plant root has the aptitude to develop as a new plant. In fact, the relatively bigger root divisions may be directly planted in their permanent positions outdoors. Nevertheless, if you want to obtain the maximum number of new plants to grow, slice the roots in smaller segments, usually having a length of around 3 cm, and plant them in containers. Keep these containers in partial shade in a cold frame, till the roots divisions give rise to new shoots. You will find that the new shoots will emerge very quickly and once these shoots have grown sufficiently tall, plant them outdoors during the summer.
Pennyroyal's volatile oil contains pulegone (between 27-92%), isopulegone, menthol, and other terpenoids. Pennyroyal also contains bitters and tannins.
Medicinal formulations prepared with pennyroyal may be used internally in several ways - as a mixture, infusion or a tincture. To ingest the herb as an infusion, you may put one or two teaspoons of dehydrated mint leaves in a cup of steaming water and leave it for approximately 10 to 15 minutes with a view to enable the leaves to form a solution. Take the infusion three times every day to obtain the utmost results of the herb. Likewise, you may also consume a dosage of 1 to 2 ml of pennyroyal tincture three times every day to get rid of your medical conditions.
Side effects and cautions
Since pennyroyal is an effective abortifacient (a medication that induces abortions) this herb should never be used during pregnancy. Although, several pennyroyal products that repel fleas are available commercially in the market as an effective medication to protect animals from mites, it is advisable never to use any such products for your pets, including dogs and cats.
Collection and harvesting
The most appropriate time to harvest pennyroyal leaves and edges of the stalks for fresh use of the herb is when the plant has grown up to a height of six inches or 15 cm. It is important to note that it is essential to undertake the cropping during the daytime after the dew disappears and prior to the flowering season of the plant. The best way to harvest the upper growth of the stalks is to cut the plant higher than the lower cluster of leaves and subsequently hang down the cropped stems with the leaves on them in a shade for drying. When the leaves have dried out or desiccated, store them in airtight containers and put them away from sunlight. Crush the leaves just before using them, as this will enable you to obtain the utmost essence of the herb. Alternately, one may even preserve the leaves by chilling them in ice cubes, soaking them in oil or even butter for use whenever necessary.