Glycyrrhiza glabra Seeds | Liquorice Root
LATIN NAME: Glycyrrhiza glabra
COMMON NAME: Liquorice
Plant Profile
Bundles of liquorice root were placed in the tomb of Tutankhamun, and three thousand years later a chemist in a Yorkshire town was boiling the same root down with sugar and treacle and stamping the cooling sheet into small discs. The root has been dug across that whole span, and the reason is one molecule: glycyrrhizin, a triterpene saponin that tastes many times sweeter than sucrose and leaves a long, faintly bitter tail.
Below ground the plant runs horizontal woody rhizomes, pale yellow inside, that travel some distance before throwing up a new shoot; the root of trade is largely this rhizome. Above ground, stems to a metre and a half carry pinnate leaves and pale violet-blue pea flowers in axillary spikes.
The medicinal trade runs on two species. Glycyrrhiza glabra comes from the Mediterranean and western Asia, with smooth leaflets and a pale, smooth-skinned rhizome. Glycyrrhiza uralensis, from northern China and Mongolia, carries glandular hairs and is the main commercial root of the East Asian market.
Liquorice spread with cultivation rather than with wild dispersal. It was grown in the monastic and castle gardens of medieval Europe and later around the English liquorice towns, and it naturalised along riverbanks that flood in winter and dry out in summer. It wants deep, moist soil.
Because glycyrrhizin can raise blood pressure and deplete potassium in quantity, the modern formulary often specifies a deglycyrrhizinated liquorice in which the sweet saponin has been removed and the flavonoid fraction retained. That product line explains why the root is peeled, split and blended with such care before it reaches a factory.
Science & Biotechnology
Glycyrrhizin, also written glycyrrhizic acid, is the sweet principle, accompanied by the flavonoid glycoside liquiritin, its aglycone liquiritigenin, the chalcone isoliquiritigenin, and the prenylated isoflavonoid glabridin in the dark outer bark. The split is practical as well as chemical: the sweetness lives in the inner tissue, and the bitter edge and the colour in the skin.
Because the two pools behave differently, extraction is staged. The peeled root gives a cleaner sweet extract; unpeeled root gives more colour and a stronger phenolic finish. Skin material is often diverted to cosmetic work, where glabridin is the compound of interest in skin-brightening research.
Hydrolysis of glycyrrhizin strips off its sugar chains and leaves glycyrrhetinic acid, the aglycone used as the starting point for semi-synthetic derivatives in anti-inflammatory research. Because wild stands are slow to regrow, cell suspension and hairy-root cultures of Glycyrrhiza have been developed to produce glycyrrhizin in bioreactors, along a route that runs from squalene through beta-amyrin.
Uses & Benefits
Roots are lifted in autumn when sugar content is at its height, cut from the rhizome network with a fork, and washed free of soil. Peeling is done while the root is fresh and the skin still slips; the yellow core left behind is the peeled root of confectionery and pharmacy. It is then cut into short segments, dried slowly in shade, and sorted before baling.
The English liquorice industry at Pontefract gave the world the stamped disc that still carries the name. In brewing it is a traditional addition to dark porter and stout, where it darkens the colour and rounds the roast edge; in tobacco a casing sweetens and binds a blend; in candy it is the base of every black sweet.
Growing from Seed
Seed carried in hard coats is best nicked and soaked in warm water for a night before sowing. Cuttings are faster: take pieces of thick rhizome about fifteen centimetres long with at least two buds and lay them horizontally in a trench. Work a deep bed of two parts loam, one part sand and one part compost, with the subsoil broken to half a metre, and space the pieces forty to fifty centimetres apart.
Liquorice wants steady moisture in the growing season and dry feet in winter, so water deeply and less often, since the roots follow the wetting front downward. Weed hard in the first season, and lift the crop only when the rhizome mass is thick enough to be worth the fork.
The great risk in heavy ground is root rot, so avoid standing water, keep the bed raised where the water table is high, and never replant into ground where a previous crop rotted. Cutworms notch the young shoots at soil level and slugs work the same zone in damp beds; night inspections during planting season are worth more than any spray.
Our Take
Liquorice is a long-term commitment with a small reward at the fork, but nothing else quite matches lifting a pale root that smells of aniseed. Give it room to run. For a legume rotation without the wait, try fenugreek or the deep-rooted astragalus, and for the eastern medicinal material the northern Ural licorice is the species to sow.
Related Reading
Gardeners who grow Liquorice often pair it with these related subjects: