Aldrovanda vesiculosa

Lore & Background

Aldrovanda vesiculosa was first mentioned and illustrated in 1691 by Leonard Plukenet based on collections from India, who named it Lenticula palustris Indica. The modern botanical name originates from Gaetano Lorenzo Monti, who described Italian specimens in 1747 and named them Aldrovandia vesiculosa in honor of the Italian naturalist Ulisse Aldrovandi. When Carl Linnaeus published his Species Plantarum in 1753, the 'i' was dropped from the name to form the modern binomial.

The plant consists of floating stems reaching 6–40 cm, with 2–3 mm trap leaves growing in whorls of 5 to 9. Traps are held by petioles with air sacs aiding flotation. One end of the stem continually grows while the other dies off. Growth is rapid, producing a new whorl once or more each day in optimal conditions. The traps are lined with trigger hairs and snap shut in 10–20 milliseconds, making it one of the fastest plant movements. Each trap is surrounded by 4–6 bristles that prevent triggering by debris.

Aldrovanda vesiculosa reproduces most often through vegetative reproduction, producing offshoots every 3–4 cm. Winter-hardy forms produce turions as a frost survival strategy, sinking to the bottom where they can withstand temperatures as low as −15 °C. In spring, turions float to the top and germinate when water temperatures rise above 12–15 °C. Non-dormant turion-like organs can also form in response to summer drought.

Reader's Guide

Aldrovanda vesiculosa is the second most widely distributed carnivorous plant species, native to Europe, Asia, Africa, and Australia. It is spread mainly through the movement of waterfowl, with most populations located along avian migratory routes. Over the last century, the species has declined to only 50 confirmed extant populations worldwide and is listed as extinct in an increasing number of countries. Potentially invasive populations exist in the eastern United States, introduced by carnivorous plant hobbyists in the 1970s to backyard ponds in New Jersey, Virginia, and the Catskills of New York.

The species faces significant conservation threats from habitat degradation and modification, including residential and commercial development, agricultural and aquacultural activities. Across Europe, acidification, canalization, drainage, eutrophication, pollution, and habitat modification are identified as threats. Potential illegal trade also adds complexity to conservation. The waterwheel plant inhabits clean, shallow, warm standing water with high light availability, low nutrient concentrations, and slightly acidic pH around 6. It is highly intolerant of habitat degradation, and even minor changes in water chemistry can lead to local extinction. It is kept by hobbyists.

Did You Know?

• Aldrovanda vesiculosa is the sole extant species in its genus, with up to 19 extinct species known in the fossil record.
• Winter-hardy forms produce turions that can withstand temperatures as low as −15 °C.