Mysterious and fascinating, insectivorous plants have always stirred people’s curiosity and enthusiasm. And recently, the Jardin botanique acquired some new specimens for its next exhibition!
Carnivorous or insectivorous?
The source of numerous legends like the one about “The man-eating tree of Madagascar” popular in the nineteenth century, carnivorous plants are not that voracious. The prey captured most often consists of various insects: ants, termites, flies – which is why we properly talk of insectivorous plants. Those sporting the biggest traps, like pitcher plants, may accidentally capture frogs or small mammals. In those rare cases we can speak of carnivorous plants, but never fear: they won’t attack! That faculty of attracting, capturing and digesting living prey has evolved in about 600 species of plants, spread over eighteen genuses and eight botanical families.
Insectivorous plants grow most often in acidic and nutrient-poor wetlands, like peat bogs. After several thousand years in those habitats, they’ve developed specialized leaves in different types of traps, and the digestion of insects provides nutritional elements that are otherwise not, or hardly, available in their environment.
Acquisitions at the Jardin
For the new exhibition, specimens of a number of pitcher plant species have been arriving from as far away as Sri Lanka. Coming straight from the airport, they’ve been acclimatized in a greenhouse newly fitted out to receive them, where a reverse osmosis system designed to demineralize water has been installed. That system allows for the spraying and fogging of the greenhouse so that a high humidity rate is maintained. New species of heliamphora, sarracenia, drosera and others have joined our collection.
Nepenthes, or tropical pitcher plants, possess passive traps with leaves modified into urns. Insects, attracted by the nectar-producing glands located under the operculum, a sort of umbrella surmounting the urn, penetrate the trap and slip down internal surfaces on top of which an impassable bulge sits. The prey ends up drowning in the digestive liquid at the bottom of the urn. Pitcher plants use a combination of the enzymes they secrete and bacteria present in the environment to digest their meals.
Other specimens, like dionaea (Venus flytrap), have been multiplied in a culture in vitro by a specialized firm. The Venus flytrap possesses an active snap trap made up of a pair of colored lobes edged with numerous hairs. As soon as the prey comes into contact with those sensitive hairs, these snap together at a record speed of 1/30 of a second! The hairs fit together perfectly when the trap closes. The prey is then digested thanks to enzymes produced by glands situated on the inner side of the lobes. A perennial, the Venus flytrap reaches its full development around the age of 10. So come back to see these specimens in a few years!
A brand-new exhibition
During the last year, the horticulture team has taken on quite the challenge to get this new exhibit ready. The insectivorous plants above are just a sample of what’s in store for you. And don’t worry: they’ve been well fed!