Common Name: Liquorice

General Information

Glycyrrhiza glabra is a herbaceous perennial plant producing a cluster of erect, simple or branching stems from a robust, rhizomatous rootstock with a central taproot. The stems become more or less woody at the base, usuallu growing 50 - 80cm tall, but occasionally reaching 150cm[, , ]. The plant has a very extensive root system which can send up new shoots for up to 7 metres in all directions[].
Licorice root is one of the most commonly used herbal medicines and sweeteners/flavourings in the temperate zone, the roots being obtained from this species and also from Glycyrrhiza inflata and Glycyrrhiza uralensis. This species is harvested from the wild for local use and also cultivated in gardens and for commercial use.
This species is a noxious weed in cotton and other cultivated crops in central Asia[].

Known Hazards

Whilst licorice is basically a very safe and effective medicine, when used over a long period or in large quantities it can raise the blood pressure. A gross overdose of the root can cause oedema, high blood pressure and congestive heart failure[, ].

Botanical References

, ,

Range

Eurasia - France, through southern Russia, southern Siberia to northwest China and Mongolia; through Greece and the Levant to Pakistan and NW. India

Habitat

Dry open places[], especially in sandy places near the sea[]. Margins of farms, roadsides, saline areas; at elevations from 500 - 1,300 metres in northwest China[]. Steppes, semideserts, desert oases in central Asia[]..

Properties

Weed Potential	Yes
Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Perennial
Height	0.70 m
Pollinators	Insects
Cultivation Status	Cultivated, Wild

Cultivation Details

Glycyrrhiza glabra is a plant of the temperate zone, where it is found at elevations up to 1,300 metres. It grows best in areas where annual daytime temperatures are within the range 14 - 25°c, but can tolerate 5 - 30°c[]. When dormant, the plant can survive temperatures down to about -15°c, but young growth in spring is more tender and can be severely damaged at 0°c[, ]. It prefers a mean annual rainfall in the range 500 - 1,000mm, but tolerates 300 - 1,200mm[].
Requires a deep well cultivated fertile moisture-retentive soil for good root production[]. Prefers a sandy soil with abundant moisture and does not flourish in clay[]. Prefers a pH in the range 6.5 - 7.5, tolerating 5.5 - 8.2[]. Slightly alkaline conditions produce the best plants[]. The plant thrives in a maritime climate[] and can tolerate moderate levels of soil salinity[].
Liquorice is often cultivated for its edible root which is widely used in medicine and as a flavouring. There are some named varieties[].
The ssp. glandulifera grows in Russia and produces adventitious roots up to 10 cm thick[].
Yields of 10 - 12 tonnes per hectare were considered good in the early 20th century, this only being attained in the fourth year of growth[].
Yields of fresh root can reach 20 - 50 tonnes per hectare when harvested every 2 - 3 years[].
Unless seed is required, the plant is usually prevented from flowering so that it puts more energy into producing good quality roots[].
The bruised root has a characteristic sweet pungent smell[].
Plants are slow to settle in and do not produce much growth in their first two years after being moved[]. The young growth is also very susceptible to damage by slugs and so the plant will require some protection for its first few years[].
A fairly deep-rooting plant, the roots are up to 120cm long[]. It can be difficult to eradicate once it is established[].
This species has a symbiotic relationship with certain soil bacteria, these bacteria form nodules on the roots and fix atmospheric nitrogen. Some of this nitrogen is utilized by the growing plant but some can also be used by other plants growing nearby[].

Edible Uses

Root - raw or used as a flavouring. The source of liquorice powder that is extracted and used in sweets, baked goods, ice cream, soft drinks etc[, , , ], it is also used medicinally. A sweet and delicious flavour, but the root is very fibrous[]. The root contains glycyrrhizin, a substance that is 50 times sweeter than sucrose[, , ].

The dried root is often used for chewing, it is excellent for teething children and also as a tooth cleaner[, ].

A tea made from the roots is an excellent thirst quencher[]. The powdered root is also used as a sweetener in other herb teas[].

The leaves are used as a tea substitute in Mongolia[].

Medicinal

Liquorice his one of the most commonly used herbs in Western herbal medicine and has a very long history of use, both as a medicine and also as a flavouring to disguise the unpleasant flavour of other medications[]. It is a very sweet, moist, soothing herb that detoxifies and protects the liver[] and is also powerfully anti-inflammatory, being used in conditions as varied as arthritis and mouth ulcers[].

The root of this plant is one of the three main commercial sources of licorice (the other two are Glycyrrhiza inflata and Glycyrrhiza uralensis). Studies have shown that the range and content of medicinally active compounds in this species closely resemble those of Glycyrrhiza inflata and that this species can be used in the same ways that Glycyrrhiza inflata is used. Glycyrrhiza uralensis, however, exhibits markedly different contents of the various active compounds and has subtly different applications medicinally. For example, the root of Glycyrrhiza uralensis has a stronger oestrogenic activity than the other licorices, is a more powerful antitussive and also exerts a stronger inhibitory effect upon aldose reductase activity[].

The root is alterative, antispasmodic, demulcent, diuretic, emollient, expectorant, laxative, moderately pectoral and tonic[, , , , , ]. The root has also been shown to have a hormonal effect similar to the ovarian hormone[]. Liquorice root is much used in cough medicines and also in the treatment of catarrhal infections of the urinary tract[]. It is taken internally in the treatment of Addison's disease, asthma, bronchitis, coughs, peptic ulcer, arthritis, allergic complaints and following steroidal therapy[].
Externally, the root is used in the treatment of herpes, eczema and shingles[].
Licorice should be used in moderation and should not be prescribed for pregnant women or people with high blood pressure, kidney disease or taking digoxin-based medication[].
Prolonged usage raises the blood pressure and causes water retention[, ]. See also the notes above on toxicity.
The root is harvested in the autumn when 3 - 4 years old and is dried for later use[, ].

Other Uses

The plant yields a substance that is used for etching steel sections in photomicrographic work[].

The dried root is often used for chewing, it is excellent for teething children and also as a tooth cleaner[, ].

Extracts from the root are used as a foaming agent in beers and fire extinguishers[].
Extracts from various parts of the plant, but especially the roots, are used as ingredients in commercial cosmetic ingredients where they serve as skin conditioners, emollients, moisturers, soothing agents, smoothing agents, bleaches, perfumes and antioxidants[].

A fibre obtained from the roots is used for insulation, wallboard, boxboard etc[, ]. The fibres can be used after the medicinal and flavouring constituents of the root have been removed[].

Propagation

Pre-soak the seed for 24 hours in warm water and then sow spring or autumn in a greenhouse[]. Prick out the seedlings into individual pots when they are large enough to handle, and grow them on for their first winter in a greenhouse. Plant out in late spring or early summer when in active growth. Plants are rather slow to grow from seed[].
Division of the root in spring or autumn. Each division must have at least one growth bud. Autumn divisions can either be replanted immediately or stored in clamps until the spring and then be planted out[]. It is best to pt up the smaller divisions and grow them on in a cold frame until they are established before planting them out in the spring or summer.