Sundew

July 12th, 2008

Botanical Name: Drosera rotundifolia (LINN.)
Family: Droseraceae
Synonyms: Dew Plant. Round-leaved Sundew. Red Rot. Herba rosellae. Sonnenthau rosollis. Rosée du Soleil.
Part Used: The flowering plant dried in the air, not artificially.
Habitat : Sundews generally grow in seasonally moist or more rarely constantly wet habitats with acidic soils and high levels of sunlight. Common habitats include bogs, fens, swamps, marshes, the tepuis of Venezuela, the wallums of coastal Australia, the Fynbos of South Africa, and moist streambanks. Many species grow in association with sphagnum moss, which absorbs much of the soil’s nutrient supply and also acidifies the soil, making nutrients less available to plant life. This allows sundews, which don’t rely on soil-bound nutrients, to flourish where more dominating vegetation would usually outcompete them.

That being said, the genus is very variable in terms of habitat. Individual sundew species have adapted to a wide variety of environments, including atypical habitats such as rainforests, deserts (ex. D. burmannii and D. indica), and even highly shaded environments (Queensland Sundews). The temperate species, which form hibernacula in the winter, are an example of such adaptation to habitats; in general, sundews tend to prefer warm climates, and are only moderately frost-resistant. Britain, and in many parts of Europe, India, China, Cape of Good Hope, New Holland, North and South America, Russian Asia.

Description: This little insectivorous plant is found growing in muddy edges of ponds, bogs and rivers, where the soil is peaty. It is a small herbaceous, perennial, aquatic plant, with short and slender fibrous root, from which grow the leaves. These are remarkable for their covering of red glandular hairs, by which they are readily recognized, apart from their flowers which only open in the sunshine. Their leaves are orbicular on long stalks, depressed, Iying flat on ground and have on upper surface long red viscid hairs, each having a small gland at top, containing a fluid, which looks like a dewdrop, hence its name. This secretion is most abundant when the sun is at its height. Flower-stems erect, slender, 2 to 6 inches high, at first coiled inward bearing a simple raceme, which straightens out as flowers expand; these are very small and white, appearing in summer and early autumn. Seeds numerous, spindleshaped in a loose chaffy covering contained in a capsule. These hairs are very sensitive, they curve inward slowly and catch any insects which alight on them; the fluid on the points also retains them. After an insect has been caught, the glandular heads secrete a digestive fluid which dissolves all that can be absorbed from the insect. It has been noted that secretion does not take place when inorganic substances are imprisoned.

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Part of leaf ->. Leaf and tentacle->...

Flowers and fruit

Flower of D. kenneallyi

The flowers of sundews, as with nearly all carnivorous plants, are held far above the leaves by a long stem. This physical isolation of the flower from the traps was originally thought to be an adaptation meant to avoid trapping potential pollinators; a recent study, however, indicated that Drosera attract distinct types of insects as pollinators and prey, with little overlap. Instead, the tall flower stalks probably help raise the flowers to a height where they are noticeable to pollinators. The mostly unforked inflorescences are spikes, whose flowers open one at a time and usually only remain open for a short period. Flowers open in response to light intensity (often opening only in direct sunlight), and the entire inflorescence is also helitropic, moving in response to the sun’s position in the sky.
The ovary is superior and develops into a dehiscent seed capsule bearing numerous tiny seeds.

Roots

Drosera anglica with prey

The root system of most Drosera is only weakly developed. It serves mainly to absorb water and to anchor the plant to the ground; the roots are relatively useless when it comes to nutrient uptake. A few South African species use their roots for water and food storage. Some species have wiry root systems that remain during frosts if the stem dies. Some species such as Drosera adelae and Drosera hamiltonii use their roots for asexual propagation, by sprouting plantlets along their length. Some Australian species form underground corms for this purpose, which also serve to allow the plants to survive dry summers. The roots of pygmy sundews are often extremely long in proportion to their size, with a 1 centimeter (0.4 in.) plant extending roots over 15 centimeters (6 in.) beneath the soil surface. Some pygmy sundews, such as D. lasiantha and D. scorpiodes, also form adventitious roots as supports. Drosera intermedia and D. rotundifolia have been reported to form arbuscular mycorrhizas

Plant characteristics: Sundews are perennial (or rarely annual) herbaceous plants, forming prostrate or upright rosettes between 1 centimeter (0.4 in.) and 1 meter (39 in.) in height, depending on the species. Climbing species form scrambling stems which can reach much longer lengths, up to 3 meters (10 ft.) in the case of D. erythrogyne. Sundews have been shown to be able to achieve a lifespan of 50 years. The genus is so specialized for nutrient uptake through its carnivorous behavior that the pygmy sundew is missing the enzymes (nitrate reductase in particular ) that plants usually use for the uptake of earth-bound nitrates.

Constituents: The juice is bitter, acrid, caustic, odourless, yielding not more than 30 per cent ash, and contains citric and malic acids.

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).

Medicinal Action and Uses: 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. Sundews have also been used as an aphrodisiac and to strengthen the heart, as well as to treat sunburn 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.

Used with advantage in whooping-cough, exerting a peculiar action on the respiratory organs; useful in incipient phthisis, chronic bronchitis, asthma, etc., the juice is said to take away corns and warts, and may be used to curdle milk. In America it has been advocated as a cure for old age; a vegetable extract is used together with colloidal silicates in cases of arterio sclerosis.
Dosages: 2 fluid drachms of the saturated tincture added to 4 fluid drachms of water or wine and a teaspoonful taken for a dose. Fluid extract, 10 to 20 drops. Solid extract, 2 to 5 grams

Other Uses:The corms of the tuberous sundews native to Australia are considered a delicacy by the Australian Aborigines. Some of these corms were also used to dye textiles, while another purple or yellow dye was traditionally prepared in the Scottish Highlands using D. rotundifolia. A sundew liqueur is also still produced using a recipe that has its roots in the 14th century. It is made using fresh leaves from mainly D. capensis, D. spatulata, and D. rotundifolia.

Disclaimer:
The information presented herein is intended for educational purposes only. Individual results may vary, and before using any supplements, it is always advisable to consult with your own health care provider.

Resources:
http://www.botanical.com/botanical/mgmh/s/sundew99.html
http://en.wikipedia.org/wiki/Sundew