Aldrovanda

Plant Genus: Aldrovanda
  
Common Name: The Waterwheel Plant
  
Number of Species: 1
  
Place(s) found naturally: Africa, Asia, Australia & Europe.

Aldrovanda vesiculosa (Droseraceae)

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Aldrovanda vesiculosa.
This plant is one of two genera of carnivorous plants that grow in water, the other being some of the Utricularia (bladderworts).  All carnivorous plants have found a way to get their minerals from the prey that they trap.  They need to do this, because the soil or water that they grow in is very low in minerals, or does not contain the right minerals that the plants need to grow. All these plants still use photosynthesis.  They have chlorophyll in their cells, just like all other plants.

The plant Aldrovanda vesiculosa is found in Africa, Australia, Europe, Japan and India, but it has now become extinct in the wilds of Japan. In Europe, the plant is dying out due to high levels of pollution. Aldrovanda grows in acidic water, floating just below the surface. As with normal water weeds, it grows amongst other water plants e.g. reeds. However, unlike most other water plants, Aldrovanda has no roots.

In places where winters are cold, the plant goes dormant by forming a tightly rolled bud. Some Utricularia (bladderworts) do the same. In warm places, Aldrovanda grows all year round. In cultivation, never allow the plant to freeze solid. The plant grows to about six inches (15 cm) long and as one end grows, the other end dies. The plant has traps that look like those of a Venus Fly Trap (Dionaea muscipula) (VFT). These traps also move in the same way. There are about six to nine traps, each one at the end of a leaf.  These leaves grow in whorls around the stem.  The traps also have bristles. These pointy bristles may be there to help to prevent the traps being damaged as the plant floats around other plants.

The plant flowers in the summer.  The flowers are single, white in colour and grow above the water level. The traps, which are only about 10th of an inch across, are translucent green in colour and look similar to a clamshell. Each side of the trap is lined with a large number of teeth. Inside the trap there are trigger hairs and digestive glands. Unlike all other carnivorous plants, it has not been found what actually lures the prey to these traps. Some of the lures in other carnivorous plants are colour, smell and taste.

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Aldrovanda vesiculosa.
The trap closes like the VFT, with the teeth interlocking to stop the prey from escaping before the trap is fully closed.  Because the plant grows under water, it uses a viscid secretion to make the trap waterproof. This secretion is released after the plant has first forced the water out of the trap, by squeezing the two lobes together. The plant is not that easy to grow in cultivation on a long-term basis.  When growing these plants, use peaty water; keep it free from algae and tadpoles, as both are enemies of this plant.  It is helpful however, to keep water fleas (Daphnia) in the water with the plant.  These provide food and also help to keep the water clear.

For more plant information check out Rick Walker's CP Database