The Waterwheel Plant, scientifically known as Aldrovanda vesiculosa, is a distinctive aquatic carnivorous plant. This species is the sole living member of its genus within the Droseraceae family, which also includes the Venus flytrap. Unlike most plants, Aldrovanda vesiculosa captures and consumes small aquatic invertebrates. Its appearance, characterized by whorls of leaves resembling a wheel, gives rise to its common name.
A Carnivorous Marvel
Aldrovanda vesiculosa employs snap traps to capture its prey, a mechanism that functions underwater. These traps are formed by two hinged lobes, similar to those of the Venus flytrap but smaller, typically 2 to 3 millimeters. The traps are oriented outwards along the stem and are internally lined with delicate trigger hairs.
When an unsuspecting aquatic invertebrate, such as a mosquito larva, daphnia, or water flea, brushes against these trigger hairs, the trap snaps shut with remarkable speed. This rapid closure can occur in as little as 10 to 20 milliseconds. The swift action ensures that the prey is ensnared within the trap lobes.
Once captured, the plant begins its digestive process. Glands within the trap release enzymes that break down the invertebrate, allowing the plant to absorb the released nutrients. This carnivorous adaptation allows Aldrovanda vesiculosa to supplement its nutritional intake.
Natural Habitat and Decline
Aldrovanda vesiculosa naturally inhabits clear, shallow, and still aquatic environments. It prefers warm, standing water bodies with low nutrient levels and a slightly acidic pH, typically around 6. These habitats include small fens, peat-bog pools, billabongs, lakes, lagoons, and river deltas, where it often floats among other aquatic vegetation.
Historically, Aldrovanda vesiculosa was widely distributed across Europe, Asia, Africa, and Australia. Its dispersal is largely attributed to waterfowl, which can transport plant fragments or dormant buds called turions to new locations. Consequently, many Aldrovanda populations are found along avian migratory routes.
Despite its broad historical range, the species has experienced a significant decline over the last century, becoming increasingly rare and even extinct in many countries. This decline is primarily due to habitat loss and degradation from human activities. Water pollution, which increases nutrient levels and alters water chemistry, also negatively impacts the plant’s sensitive habitat.
Cultivation for Conservation and Hobbyists
Cultivating Aldrovanda vesiculosa requires specific conditions that mimic its natural habitat. The plant thrives in clean water with low mineral content. Distilled water or rainwater are ideal choices, as tap water often contains minerals and chlorine that can be detrimental to its health.
Appropriate light conditions are also important, with bright, indirect light preferred. Temperatures should be maintained within a range of 20°C to 26°C (68°F to 78°F) for optimal growth and trap function. Aldrovanda vesiculosa is a free-floating plant, although companion plants like water lilies can be beneficial by providing shade and fostering a healthy aquatic environment.
Propagation of Aldrovanda vesiculosa is commonly achieved through vegetative reproduction. In favorable conditions, the plant can produce offshoots every few centimeters, with new plants forming as the older sections die off. It also forms specialized overwintering buds called turions, which are compact, non-carnivorous structures that sink to the bottom during colder months and float back to the surface in spring to resume growth.
Successful cultivation by hobbyists plays a role in conservation efforts for this endangered species. By maintaining healthy populations in controlled environments, hobbyists contribute to genetic preservation and provide a buffer against the loss of wild populations. This collective effort supports the long-term survival of Aldrovanda vesiculosa.