Drosera rotundifolia

Drosera rotundifolia (the common sundew or round-leaved sundew) is a species of sundew, a carnivorous plant often found in bogs, marshes and fens. One of the most widespread sundew species, it is generally circumboreal, being found in all of northern Europe, much of Siberia, large parts of northern North America, Japan and is also found on New Guinea.

Morphology
The leaves of the common sundew are arranged in a basal rosette. The narrow, hairy 1.3-5 centimetre long petioles support 4-10 millimetres long laminae. The upper surface of the lamina is densely covered with red glandular hairs that secrete a sticky mucilage (see Carnivory section, below).

A typical plant has a diameter of around 3-5 centimetres, with a 5-25 centimetre tall inflorescence. The flowers grow on one side of a single slender, hairless stalk that eminates from the centre of the leaf rosette. White or pink in colour, the five-petalled flowers produce 1-1.5 mm light brown seeds that are slender and tapered.

In the winter, D. rotundifolia produces a hibernaculum in order to survive the cold conditions. This consists of a bud of tightly curled leaves at ground level.

Carnivory
The plant feeds on insects, which are attracted to its bright red colour and its glistening drops of mucilage, loaded with a sugary substance, that cover its leaves. It has evolved this carnivorous behaviour in response to its habitat, which is usually poor in nutrients or 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 nitrates and other nutrients from their bodies.

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.

It is found in much of Europe, including the British Isles, most of France, the Benelux nations, Germany, Denmark, Switzerland, Poland, Belarus, the Baltic countries, Sweden and Finland, as well as northern portions of Spain, Romania and Iceland and southern regions of Norway and Greenland. It is infrequent in Austria and Hungary, and some populations are scattered around the Balkans.

In the UK, this is the most common form of sundew and can be found on Exmoor, Dartmoor, Sedgemoor, the Lake District, Pennines and in Scotland. It is usually found in bogs, marshes and in hollows or corries on the side of mountains.

In Asia, it is found across Siberia and Japan, as well as parts of Turkey, the Caucasus region, the Kamchatka Peninsula and southern parts of Korea. Populations can also be found on the island of New Guinea.

Habitat
The common sundew thrives in wetlands such as marshes and fens. It is also found in wet stands of black spruce, Sphagnum bogs, silty and boggy shorelines and wet sands. It prefers open, sunny or partly sunny habitats.

Conservation
In the UK, it is a protected wild flower and therefore it is a criminal offence to remove all or part of one of these plants from the wild.

In North America, the roundleaf sundew is considered endangered in the U.S. states of Illinois and Iowa, exploitably vulnerable in New York and threatened in Tennessee. 

Medicinal Properties
According to D.H. Hall, et al., Drosera rotundifolia plant extracts show great efficacy as an anti-inflammatory and anti-spasmodic, more so than D. madagascariensis, as a result of the flavinoids such as hyperoside, quercetin and isoquercetin, but not the naphthoquinones present in the extracts. The flavinoids are thought to affect the M3 muscarinic receptors in smooth muscle, causing the antispasmodic effects. Ellagic acid in D. rotundifolia extracts has also been shown to have anti-angiogenic effects.

Gallery
Rundbladet Soldug Rundblättriger Sonnentau Rondfolia drozero Drosera à feuilles rondes Drosera rotundifolia Apskritalapė saulašarė Kereklevelű harmatfű Ronde zonnedauw モウセンゴケ Rosiczka okrągłolistna Drosera rotundifolia Pyöreälehtikihokki Rundsileshår