Aldrovanda vesiculosa
| Aldrovanda vesiculosa | |
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| Scientific classification | |
| Kingdom: | Plantae |
| (unranked): | Angiosperms |
| (unranked): | Eudicots |
| (unranked): | Core eudicots |
| Order: | Caryophyllales |
| Family: | Droseraceae |
| Genus: | Aldrovanda |
| Species: | A. vesiculosa |
| Binomial name | |
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Aldrovanda vesiculosa L. |
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| Distribution | |
| Synonyms | |
*Drosera aldrovanda F.Muell. |
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Aldrovanda vesiculosa, commonly known as the waterwheel plant, is the sole extant species in the flowering plant genus Aldrovanda of the family Droseraceae. The plant captures small aquatic invertebrates using traps similar to those of the 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.
While the genus Aldrovanda is now monotypic, up to 19 extinct species are known in the fossil record. While the species displays a degree of morphological plasticity between populations, A. vesiculosa possesses a very low genetic diversity across its entire range.
A. vesiculosa has declined over the last century to only 50 confirmed extant populations worldwide. These are spread across Europe, Africa, Asia and Australia.
A. vesiculosa is a rootless aquatic plant; seedlings develop a short protoroot; however, this fails to develop further and senesces. The plant consists of floating stems reaching a length of 6–40 cm. The 2–3 mm trap leaves grow in whorls of 5-9 in close succession along the plant's central stem. 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 (4–9 mm/day in Japanese populations), 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 (20 °C). Each trap is surrounded by between four and six 6–8 mm long bristles which prevent triggering of traps by debris in the water.
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Wikipedia