Aldrovanda vesiculosa (waterwheel)

Aldrovanda vesiculosa or waterwheel plant, is a aquatic plant that captures small aquatic creatures similar the to venus flytrap.The traps are arranged in whorls around a central, free-floating stem, giving rise to the common name. This is one of the few plant species capable of rapid movement. The actual traps are held by petioles which hold air sacks that aid in flotation. One end of the stem continually grows while the other end dies off. Growth is quite rapid, so that in optimal conditions a new whorl is produced once or more each day. The actual traps consist of two lobes which fold together to form a snap-trap similar to that of the Venus fly trap, except that they are smaller and underwater. These traps, which are twisted so that the trap openings point outward, are lined on the inside by a fine coating of trigger hairs, snapping shut in response to contact with aquatic invertebrates and trapping them. The closing of this trap takes 10-20 milliseconds, making it one of the fastest examples of plant movement in the kingdom. This trapping is only possible in warm conditions. Each trap is surrounded by between four and six 6–8 mm long bristles which prevent triggering of traps by debris in the water.

Waterwheel reproduces most often through vegetative reproduction. In favorable conditions, adult plants will produce an offshoot every 3–4 cm, resulting in new plants as the tips continue to grow and the old ends die off and separate. Due to the rapid growth rate of this species, countless new plants can be produced in a short period of time in this fashion.

Waterwheel prefers clean, shallow, warm standing water with bright light, low nutrient levels and a slightly acidic pH (around 6). It can be found floating among Juncus, reeds, and even rice.