Rossolis Intermédiaire

Animal / predator
leaf of Drosera intermedia is predator of adult of Enallagma cyathigerum

Oblong-leaved sundew is a insect-eating plant and is legally protected in the Netherlands. The leaves are covered with long, sticky hairs which catch insects. The majority of its victims are mosquitos and small flies. Oblong-leaved sundew has slightly elongated leaves that stand diagonally straight out of the ground. It has an intenser brown-red color than round-leaved sundew. In fact, if placed on a pile of sturdy white paper, it leaves a brown coloring which can penetrate 4 layers!

Drosera intermedia, commonly known as the longleaved sundew or spoonleaf sundew, is a species of carnivorous/insectivorous plant located in a wide array of states and provinces including Quebec, Labrador, Newfoundland, Ontario, New York, Illinois, Indiana, Ohio, West Virginia, Virginia, Kentucky, Tennessee, North Carolina, Florida, Louisiana, and Idaho (Ridder & Dhondt, 1992: 129-130; NatureServe, 2014). A mature Drosera intermedia plant possesses a rosette consisting of 10-30 green leaves, each 3-4 cm in length (Ridder & Dhondt, 1992: 130). The species is a perennial herbaceous plant that has a bloom season beginning in April and lasting all the way through the late summer months (Ridder & Dhondt, 1992: 130).

Drosera intermedia is critically imperiled in Idaho, Ohio, and Kentucky, imperiled in Illinois, Indiana, Tennessee, and Louisiana, vulnerable in Virginia and Florida, apparently secure in Quebec, Labrador, Newfoundland, New York, and North Carolina, secure in Ontario, and exotic in West Virginia (NatureServe, 2014).

Drosera intermedia are known to inhabit heathland habitats with various levels of water inundations, ranging from very wet to somewhat dry (Ridder & Dhondt, 1992: 129). This species is also known to prefer water-covered patches of mud (Thum, 1988: 472). The species specifically inhabits particular areas, zones, or microhabitats within the heathland habitats including the pool, the pool edge, the wet path, the dry path, and the seepage area, which were all compared during the study. (Ridder & Dhondt, 1992: 129). The paths are defined as specific areas within the heathland that contain patches of bare padzol soil, or man-made soil, on an old path and are either inundated in water (wet path) or strictly dry land (dry path) (Ridder & Dhondt, 1992: 130). During this particular experiment, Ridder and Dhondt analyzed both spatial and temporal variation in the reproductive behavior of Drosera intermedia. Eight populations of the species dispersed over three hydrologically different heathland habitats were studied over a 4 year period (Ridder & Dhondt, 1992: 145). Eight plots were chosen in three habitat types within the State Nature reserve ‘De Kalmthoutse Heide’, which is located in the Province of Antwerp, Belgium (Ridder & Dhondt, 1992: 145). They also studied clonal species and in doing so found that clonal plant species depend mostly on asexual reproduction for the continued propagation of the species (Ridder & Dhondt, 1992: 142). These findings are supported by the fact that the form of asexual reproduction that this species is able to undergo, known as vegetative reproduction, is able to occur without the formation of seeds, spores, or other reproductive agents, none of which were present in the study site of the clonal species (Ridder & Dhondt, 1992: 142). Drosera intermedia has lower survival and occurrence rates in the dry path and the pool edge, and higher survival and occurrence rates in wet paths and the seepage areas (Ridder & Dhondt, 1992: 142). In the pool edge habitat, populations of Drosera intermedia suffer from low survival rates and often die off altogether (Ridder & Dhondt, 1992: 151). Ultimately, Ridder and Dhondt found considerable life history variation between populations of Drosera intermedia may be the result of the relationship between temporal differences amongst populations and climate related factors and that between spatial discrepancies and overall life events/experiences of the population (Ridder & Dhondt, 1992: 152).

The results of Ridder and Dhondt’s experiment conducted in Antwerp, Belgium show that in terms of asexual recruitment, Drosera intermedia had the highest asexual recruitment rates from 1986-1989, influenced by the K1 factors (Ridder & Dhondt, 1992: 159). These rates were recorded as follows; 0.77 in 1986, 0.94 in 1987, 1.15 in 1988, and 0.90 in 1989 (Ridder & Dhondt, 1992: 159). The results of their experiment also convey the fact that sexual recruitment rates in Drosera intermedia were the highest from 1987-1989 under the influence of the K4 factors (Ridder & Dhondt, 1992: 159). These rates include 0.09 in 1987, 1.22 in 1988, and 0.38 in 1989 (Ridder & Dhondt, 1992: 159). Drosera intermedia, possesses an ecological niche, or capacity as a carnivore/insectivore, particularly practicing predation of arthropods, namely insects (Thum, 1988: 472). Insect prey are an important source of nitrogen and phosphorous for Drosera intermedia (Ridder & Dhondt, 1992: 150). Thum demonstrated that Drosera intermedia catches less prey when in unsuitable, non-preferable conditions such as little water and low temperatures, as Drosera intermedia primarily preys on winged arthropods, which are scarce in cold, dry conditions (Thum, 1988: 472). The species invests the benefits attained by carnivory in various manners towards its overall fitness and survivability in its habitat, which essentially means that the species takes advantage of its status as a carnivorous organism by utilizing the energy gained through consumption of other organisms for growth and domination over lower, less dominant/advanced life forms, allowing it to maintain its niche/ecological role within its ecosystem and ultimately continue to thrive and survive as a species (Thum, 1988: 472).

Drosera intermedia, commonly known as the oblong-leaved sundew, spoonleaf sundew, or spatulate leaved sundew, is an insectivorous plant species belonging to the sundew genus. It is a temperate or tropical species native to Europe, southeastern Canada, the eastern half of the United States, Cuba, Hispaniola, and northern South America.