Drosera rotundifolia
Drosera rotundifolia, the round-leaved sundew, roundleaf sundew, or common sundew, is a species of carnivorous flowering plant that grows in bogs, marshes and fens. One of the most widespread sundew species, it has a circumboreal distribution, being found in almost all of Europe, all of Siberia, large parts of North America, Korea and Japan but is also found as far south as eastern China, the Philippines, and into the Southern Hemisphere in New Guinea.
Description
The leaves of the common sundew are arranged in a basal rosette. The narrow, hairy, long petioles support round laminae. The upper surface of the lamina is densely covered with red glandular hairs that secrete a sticky mucilage.A typical plant has a diameter of around, with a tall inflorescence. The flowers grow on one side of a single slender, hairless stalk that emanates from the centre of the leaf rosette. White or pink in colour, the five-petalled flowers produce light brown, slender, tapered seeds.
In winter, D. rotundifolia produces a hibernaculum to survive cold conditions. This consists of a bud of tightly curled leaves at ground level.
Carnivory
The plant feeds on insects, which are attracted to the glistening drops of mucilage, loaded with a sugary substance, covering its leaves. It has evolved this carnivorous behaviour in response to its habitat, which is usually poor in nutrients or is so acidic that nutrient availability is severely decreased. The plant uses enzymes to dissolve the insects which become stuck to the glandular tentacles, and extract ammonia from proteins and other nutrients from their bodies. The ammonia replaces the nitrogen that other plants absorb from the soil, and plants that are placed in a high-nitrogen environment rely less upon nitrogen from captured insects.It has been assumed that insects were also attracted to the bright red colour of the common sundew, but studies using artificial traps have suggested that colour does not affect prey attraction. New climates have been discovered with new plant growth but do not have the food associated with the requirements for growth. In areas that lack this food associated for growth, new studies have been conducted to determine how these plants are able to grow in these diverse climates where these plants area able to flourish. In one study, the carnivory of Drosera rotundifolia was tested against growing conditions where the plant's insect prey was not sufficient to promote proper growth. The group tested the plants ability to grow with limited prey but increased inorganic nutrients within the soil. The results revealed the ability of the plant to use the nutrients over the normal prey which caused the reduction in carnivory investment of the plant. These results showed that the plant would adapt to the current environment for growth using available resources as food.
Distribution
In North America, the common sundew is found in all parts of Canada except the Canadian Prairies and the tundra regions, southern Alaska, the Pacific Northwest, and along the Appalachian Mountains south to Georgia and Louisiana. In the western United States, roundleaf sundew is found in mountain fens as far south as the Sierra Nevada of California and in a disjunct cluster of fen occurrences in the Rocky Mountains of Colorado. In the eastern United States, the sundew plant is found in parts stretching from Nova Scotia down the coast into Georgia. In addition to Georgia, plants are now being seen in Alabama and Mississippi. West of the Mississippi River, plants are located along the Pacific coast from Alaska down the coast to California, with new plants detected in Iowa, Minnesota and in two recently recorded sites in Gunnison County, Colorado and Bottineau County, North Dakota.It is found in much of Europe, including the British Isles, most of France, the Benelux nations, Germany, Denmark, Switzerland, Czech Republic, Poland, Belarus, the Baltic countries, Sweden and Finland, as well as northern portions of Italy, Portugal, Spain, Romania, mountain regions of Bulgaria and in Iceland and southern regions of Norway and Greenland. It is infrequent in Austria and Hungary, and some populations are scattered around the Balkans.
In Britain, this is the most common sundew species, found widely in the west and north, from Exmoor, Dartmoor, Sedgemoor, the Lake District, Shropshire, Pennines and throughout Scotland; conversely it is rare and scattered in the Midlands and eastern England. It is usually found in bogs, marshes and in hollows or corries on the sides of mountains. It is the county flower of Shropshire. It is also common in Ireland.
In Asia, it is found across Siberia and Japan, as well as parts of Turkey, the Caucasus region, the Kamchatka Peninsula, southern parts of Korea, and northeastern and eastern China. Populations can also be found on the islands of New Guinea and Mindanao.