Liquorice (Glycyrrhiza), a genus of perennial herbaceous plants of the natural order Leguminosæ, sub-order Papilionacæ, having long, pliant, sweet roots, and generally creeping root-stocks; pinnate leaves of many leaflets, and terminating in an odd one; flowers in spikes, racemes, or heads; a 5-cleft, 2-lipped calyx, and a 2-leaved keel. The ancient Greek name, now the botanical name, signifies sweet root, and from it, by corruption, liquorice and other modern names are derived. The roots of liquorice depend for their valuable properties on a substance called Glycyrrhizine, allied to sugar, yellow, transparent, uncrystallisable, soluble in both water and alcohol, and forming compounds both with acids and with bases.
They are a well-known article of materia medica, and were used by the ancients as in modern times, being emollient, demulcent, very useful in catarrh and irritations of the mucous membrane.—The roots of the Common Liquorice (G. glabra) are chiefly in use in Europe. The plant has stems 3 to 4 feet high, and racemes of whitish violet-coloured flowers. It is a native of the south of Europe and of many parts of Asia, as far as
China. It is cultivated in many countries of Europe, chiefly in Spain, and to some extent at Mitcham in Surrey and at Pontefract in Yorkshire. The roots are extensively employed by porter-brewers. They are not imported into Britain in considerable quantity, but the black inspissated extract of them (Black Sugar or Stick Liquorice) is largely imported from the south of Europe, in rolls or sticks, packed in boxes of about 2 cwt., into which it has been run. Liquorice is sometimes used in the manufacture of sweet tobacco. Liquorice is propagated by slips; and after a plantation has been made almost three years must elapse before the roots can be dug up for use. The whole roots are then taken up. Liquorice requires a deep, rich, loose soil, well trenched and manured; the roots penetrating to the depth of more than a yard, and straight taproots being most esteemed. The old stems are cleared off at the end of each season, and the root-stocks so cut away as to prevent overgrowth above ground next year. The plant is propagated by cuttings of the root-stocks.—The roots of the Prickly Liquorice (G. echinata) are used in the same way, chiefly in Italy and Sicily, Russia, and the East.—The only American species is G. lepidota, which grows in the plains of the Missouri.