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Sundew

Sundew
© Sertürner Bildarchiv

Botanical name

(Common or Round-leaved) Sundew - Drosera rotundifolia L.

Family

Sundew family (Droseraceae)

Useful information about the plant

In Europe there are only three species: D. rotundifolia (Sundew), D. intermedia (Oblong-leaved Sundew) and D. anglica (English Sundew). All three come with a circumpolar distribution area that extends from the temperate and boreal zone in places up in the subarctic zone. The sundew is an inhabitant of moist to wet, nutrient-poor peat soils. So it likes to grow in between peat bogs, intermediate bogs and fen acidophilous areas, as well as in humid mat grasslands and heaths, and you can find it at grave edges and wet rocks.
The circular to transversely oval leaves of the sundew form a basal rosette, which is tight on the ground. In the summer 7 to 15cm long, hairy, leafless flower shafts grow from the rosettes each with 4 to 12 flowers that blossom only briefly. On the top of the leaves and small glands, especially on the edge there are reddish, glandular hairs, so-called tentacles. They act as "sticky traps" for small insects, because droplets of a sticky secretion glisten on their little heads in the sun - hence the name "sundew". The insects remain hanging stuck to the sticky glands trying to escape and thereby touch further sticky glands. In addition, the sensory stimuli writhe through the tentacles and so press the trapped insects to the leaf surface, where they are digested by the protein-digesting enzymes of the secretion. Only the caught exoskeletons of the insects remain, which are so often seen on the sundew leaves. Through this process the sundew adds to the meager nutrient supply of the moors, especially with regard to nitrogen and phosphorus.

Medicinally used plant parts (drug)

The dried herb consisting of the above-and below-ground parts of the plant is used. Originally the drug comes from the species present in Europe, mainly from the round-leaved sundew. Since the species in Europe are threatened with extinction, they are now strictly protected and may not be collected. Therefore, as a replacement drug, the drug is available from African wild stocks, mainly from D. ramentacea, D. madagascariensis and D. peltata. The procurement of this drug could be critical in the future.

Ingredients of the drug

Sundew herb contains 1.4-naphthoquinone derivatives (e.g. 7-methyl juglone, plumbagin) and flavonoids.

Descriptions of the quality

The quality of sundew herb is not specified in the pharmacopoeia (Ph. Eur, DAB, DAC), fixed. A monograph is in the supplement to DAB 6 (Suppl. B. 6).

Medical Application

Recognised medical use

With cramps and coughs (Commission E).

Traditional use

Sundew herb has no listing as a traditional medicine (§ 109a).

Medicinal herbal preparations in finished drug products

Dosage

Prepared drugs: see package insert;
Tea infusion: drink 1 cup of sundew tea 3 to 4 times a day. The dosage recommended by the Commission E of 3g per day must be increased, because the currently available African drug has a lower content of naphthoquinones than the European equivalent. The recommendation today: according to the content of naphthoquinones is 3 to 10g of drug per day.

Preparation of a tea infusion

2 to 5g of finely cut sundew herb is covered with boiling water and strained after 10 minutes

Advice

Studies on its safety have not been established yet for the purposes of using sundew herb during pregnancy and breast-feeding.

Side effects

None known

Interactions

None known

References

Drug monographs

Commission E

Further reading

Wichtl: Teedrogen und Phytopharmaka, pg. 221
Schilcher: Leitfaden Phytotherapie, pg. 246
Van Wyk: Handbuch der Arzneipflanzen, pg. 128

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