© Joseph Dougherty. All rights reserved.
Flower of Drosera filiormis, the Thread-leaved sundew.
Uses as a medicinal plant: Several medicinally active compounds are found in sundews, including flavonoids (kaempferol, myricetin, quercetin and hyperoside), quinones (plumbagin, hydroplumbagin glucoside and rossoliside (7 – methyl – hydrojuglone – 4 – glucoside), and other constituents such as carotenoids, plant acids (e.g. butyric acid, citric acid, formic acid, gallic acid, malic acid, propionic acid), resin, tannins and ascorbic acid (vitamin C).
Sundews were used as medicinal herbs as early as the 12th century, when an Italian doctor from the School of Salerno by the name of Matthaeus Platearius described the plant as an herbal remedy for coughs under the name "herba sole". It has been used commonly in cough preparations in Germany and elsewhere in Europe. Sundew tea was especially recommended by herbalists for dry coughs, bronchitis, whooping cough, asthma and "bronchial cramps". A modern study has shown that Drosera does exhibit antitussive properties.
Culbreth's 1927 Materia Medica listed D. rotundifolia, D. anglica and D.linearis as being used as stimulants and expectorants, and "of doubtful efficacy" for treating bronchitis, whooping cough, and tuberculosis. Sundews have also been used as an aphrodisiac and to strengthen the heart, as well as to treat sunburn, toothache, and prevent freckles. They are still used today in some 200-300 registered medications, usually in combination with other active ingredients. Today Drosera is usually used to treat ailments such as asthma, coughs, lung infections, and stomach ulcers.
Medicinal preparations are primarily made using the roots, flowers, and fruit-like capsules. Since all native sundews species are protected in many parts of Europe and North America, extracts are usually prepared using cultivated fast-growing sundews (specifically D. rotundifolia, D. intermedia, D. anglica, D. ramentacea and D. madagascariensis) or from plants collected and imported from Madagascar, Spain, France, Finland and the Baltics.