The common bladderwort (Utricularia vulgaris L.) is a carnivorous plant between 50 and 150 centimetres long, which means that as well as photosynthesising, it feeds on animals. Its prey, including insects and zooplankton, enable the plant to obtain additional nutrients when these cannot be found in the environment. This characteristic is a major advantage for the bladderwort, enabling it to colonise nutrient-poor ecosystems such as marshes and peat bogs. An ecological specialisation that makes it possible to occupy a particular niche in the environment.
This native macrophyte prefers calm waters and, as it has no roots, settles on the bottom or on algae. Even very weak currents carry it away. This is one of the reasons why this plant cannot proliferate in Lake Geneva. However, it has been observed on one occasion in the Geneva waters of Lake Geneva before the year 2000 (patrimoine-vert-genevois), in an area where there was no current.
When the plant is completely submerged, it is difficult to see. During the summer, twigs develop and emerge from the water, revealing pretty yellow flowers, making it easier to observe.
Bladderworts use traps to capture their prey. It has hundreds of traps fitted with trigger "hairs". When an animal touches these hairs, the prey is sucked in and the trap closes at a speed of a thousandth of a second, making escape impossible. The plant then digests the animal to recover its nutrients.
The International Union for Conservation of Nature (IUCN) has categorised it as an "endangered" species. In Switzerland, its situation is more alarming because of the limited number of wetlands. It is not illegal harvesting or even the invasion of non-native species that is endangering this species, but the very destruction of its environment that is responsible for its decline. If this carnivorous plant is to be preserved, measures need to be taken to protect its ecosystem, in particular to prevent it from becoming overgrown and drying out. The most important measure for protecting the bladderwort is the creation of ponds and marshes, given that our regions have lost 90% of wetlands.
Source :
infoflora, green heritage geneva, IUCN
Photo credit :
Creative commons licence
