Summary
English: The Droseraceae are a family of flowering plants. The family is also known as the sundew family. Members of Drosera secrete a sticky substance from their leaves that traps prey. Drosera is one of the largest genera of carnivorous plants, and individual species vary extensively in their specific morphology. Common to all members of Drosera are highly modified leaves lined with tentacle-like glandular trichomes. At the end of each trichome, a bead of highly viscous mucilage is secreted, which resembles a drop of dew. The mucilage is a fairly pure aqueous solution of acidic polysaccharides with high molecular weights, which makes the mucilage, not only highly viscous, but also very sticky; so much so, a single drop of mucilage may be stretched to lengths of up to a meter and covers one million times its original surface area. Insects and other prey animals are attracted by the smell of this mucilage and become stuck in it. Such snares are termed “flypaper traps”, but the trapping mechanism of sundews is often erroneously described as “passive”. In fact, sundew traps are quite active and sensitive, and the disturbance of one or a few trichomes quickly triggers an action potential that stimulates the rapid movement of other trichomes toward the prey. The leaf then curls in on itself, enveloping the prey for digestion. Drosera, commonly known as the sundews, comprises one of the largest genera of carnivorous plants, with at least 194 species. These members of the family Droseraceae lure, capture, and digest insects using stalked mucilaginous glands covering their leaf surfaces. The insects are used to supplement the poor mineral nutrition of the soil in which they grow. Both the botanical name (from the Greek drosos = "dew, dewdrops") and the English common name (sundew, derived from Latin ros solis, meaning "dew of the sun") refer to the glistening drops of mucilage at the tip of each tentacle that resemble drops of morning dew. Size of Drosera is 2cm it’s very colorful and attractive. The root systems of most Drosera are often only weakly developed. Serving mainly to absorb water and to anchor the plant to the ground, the roots are relatively useless for nutrient uptake. Many species of sundews are self-fertile; their flowers will often self-pollinate upon closing. Often, numerous seeds are produced. The tiny black seeds germinate in response to moisture and light, while seeds of temperate species also require cold, damp, stratification to germinate. Seeds of the tuberous species require a hot, dry summer period followed by a cool, moist winter to germinate. 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 stream banks. 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 do not rely on soil-bound nutrients, to flourish where more dominating vegetation would usually outcompete them. 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 stream banks. 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 do not rely on soil-bound nutrients, to flourish where more dominating vegetation would usually out compete them. The genus, though, 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, and even highly shaded environments (Queensland sundews). The temperate species, which form hibernacula in the winter, are examples of such adaptation to habitats; in general, sundews tend to inhabit warm climates, and are only moderately frost-resistant. Sundews were used as medicinal herbs as early as the 12th century, 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 exhibits antitussive properties.
Copyright status:
You are free: to share – to copy, distribute and transmit the work
Source:
https://commons.wikimedia.org/wiki/File:Round-leaf_sundew.jpg
