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 Hayne
Wet pine savannas (SPS-T, SPS-RF, WLPS), borrow pits, ditches.
Frequent. Jul–Sep . Thornhill 29, 161, 666 (NCSC). Specimens seen in the vicinity: Sandy Run [Hancock]: Taggart SARU 144 (WNC!); Sandy Run [Neck]: Wilbur 55301 (DUKE!). [= RAB, Weakley]
Regularity: Regularly occurring
Regularity: Regularly occurring
leaf of Drosera intermedia is predator of adult of Enallagma cyathigerum
Molecular Biology and Genetics
Barcode data: Drosera intermedia
Statistics of barcoding coverage: Drosera intermedia
Public Records: 1
Specimens with Barcodes: 11
Species With Barcodes: 1
National NatureServe Conservation Status
Rounded National Status Rank: NNR - Unranked
Rounded National Status Rank: N5 - Secure
Drosera intermedia, commonly known as the oblong-leaved sundew or spoonleaf 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 and northern South America.
D. intermedia is a perennial herb which forms a semi-erect stemless rosette of spatulate leaves up to 10 cm tall. Plants in temperate regions undergo dormancy during which they form a winter resting bud called a hibernaculum.
As is typical for sundews, the leaf blades are densely covered with stalked mucilagenous glands which secrete a sugary nectar to attract insects. These then become ensnared by the mucilage and, unless they are strong enough to escape, are suffocated or die from exhaustion. The plant then secretes digestive enzymes from sessile glands and later absorbs the resulting nutrient solution to supplement the poor mineral nutrition of the plants natural environment.
D. intermedia blooms from June through August, forming up to 15 cm. tall inflorescences bearing 3-8 white flowers. Fertilized ovaries swell to form egg-shaped dehiscent seed capsules which bear numerous tiny seeds.
Distribution and habitat
D. intermedia is one of the most widely distributed species in the genus, and one of only three Drosera species native to Europe (the others are D. rotundifolia and D. anglica). It is also found in eastern North America, Cuba, and northern South America. The Cuban and South American forms are tropical and do not form hibernacula in the winter.
D. intermedia grows in sunny, but constantly moist habitats including bogs, fens, wet sandy shorelines and wet meadows. Since it is carnivorous, it is able to occupy relatively infertile habitats including wet sand and peat. It is a relatively weak competitor, and so is excluded from more fertile sites by competition from canopy-forming perennials. It can survive high water periods as buried seeds, and then re-establish when water levels fall.
- Godwin, K. S., Shallenberger, J., Leopold, D. J., and Bedford, B. L. 2002. Linking landscape properties to local hydrogeologic gradients and plant species occurrence in New York fens: a hydrogeologic setting (HGS) framework. Wetlands 22:722–37.
- Keddy, P.A. 1981. Vegetation with Atlantic coastal plain affinities in Axe Lake, near Georgian Bay, Ontario. Canadian Field Naturalist 95: 241-248.
- Wilson, S. D. and P.A. Keddy. 1986. Species competitive ability and position along a natural stress/disturbance gradient. Ecology 67:1236-1242.
- Keddy, P.A. and A. A. Reznicek. 1982. The role of seed banks in the persistence of Ontario's coastal plain flora. American Journal of Botany 69:13-22.
- L. Diels: Droseraceae, 1906, 135 pages. (The only monograph of the family Droseraceae to date.)
- Barthlott, Wilhelm; Porembski, Stefan; Seine, Rüdiger; Theisen, Inge: Karnivoren, Stuttgart, 2004, ISBN 3-8001-4144-2
- Darwin, Charles; Insectivorous Plants (London: John Murray, 1875, 462 pages) LCCN 04-1280; Replica reprints (Scotland: Langford Press, 2002, 462 pages) ISBN 1-904078-04-4; Non-Replica reprints (New York: New York University Press, 1990, 345 pages) ISBN 978-0-8147-1822-3; Project Gutenberg online edition at https://www.gutenberg.org/etext/5765
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