ALDROVANDA VESICULOSA, commonly known as the WATERWHEEL PLANT, is the
sole extant species in the flowering plant genus
Aldrovanda of the
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.
* 1 Morphology
* 1.1 Trap
* 1.2 Reproduction
* 1.2.2 Divisions
* 1.3 Turions
* 2 Distribution
* 3 Habitat
* 4 Botanical history
* 5 Infraspecific taxa
* 6 See also
* 7 References
* 8 External links
Aldrovanda 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 it is
smaller and located 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 that prevent triggering of traps by debris in
The small, solitary white flowers of A. vesiculosa are supported
above the water level by short peduncles which arise from whorl axes.
The flower only opens for a few hours, after which the structure is
brought back beneath the water level for seed production. The seeds
are cryptocotylar: the cotyledons remain hidden within the seed coat
and serve as energy storage for the seedlings. Flowering, however, is
rare in temperate regions and poorly successful in terms of fruit and
Aldrovanda vesiculosa reproduces most often through vegetative
reproduction . In favourable 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.
Aldrovanda form turions as a frost survival strategy. At
the onset of winter, the growth tip starts producing highly reduced
non-carnivorous leaves on a severely shortened stem. This results in a
tight bud of protective leaves which, being heavier and having
released flotational gases, breaks off the mother plant and sinks to
the water bottom, where temperatures are stable and warmer. Here it
can withstand temperatures as low as −15 °C (5 °F). In the wild,
Aldrovanda turions have been observed to have a relatively low rate of
successful sinking. Those nutritious turions that fail to sink are
then grazed by waterfowl or are killed by the onset of frost. In
spring when water temperatures rise above 12–15 °C, turions reduce
their density and float to the top of the water, where they germinate
and resume growth. Non-dormant turion-like organs can also form in
response to summer drought.
Aldrovanda vesiculosa is the most widely distributed carnivorous
plant species, native to
Africa , and
Aldrovanda is spread mainly through the movement of waterfowl: plants
sticking to the feet of a bird are transported to the next aquatic
destination on the bird's route. As a result, most Aldrovanda
populations are located along avian migratory routes. Throughout the
last century the species has become increasingly rare, listed as
extinct in an increasingly large number of countries.
A. vesiculosa prefers clean, shallow, warm standing water with bright
light, low nutrient levels and a slightly acidic pH (around 6). It can
be found floating amongst
Juncus , reeds , and even rice .
Herbarium specimens deposited at the Museum National d\'Histoire
Aldrovandavesiculosa was first mentioned in 1696 by Leonard Plukenet
, based on collections made in
India . He named the plant Lenticula
pulustris 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 (an apparent orthographic
error) to form the modern binomial.
Aldrovanda vesiculosa var. rubescens A.Cross and L.Adamec (2012)
Aldrovanda vesiculosa var. aquitanica Durieu ex Diels (1906) nom.
Aldrovanda vesiculosa var. australis Darwin (1876) nom. illeg.
Aldrovanda vesiculosa var. duriaei Caspary (1859) nom. illeg.
Aldrovanda vesiculosa var. verticillata (Roxb.) Darwin (1876) nom.
* ^ Cross, A. 2012.
Aldrovanda vesiculosa. In:
List of Threatened Species . Version 2012.2. Downloaded on 17 October
* ^ "World Checklist of Selected
Plant Families". Retrieved July
* ^ Huber, H. 1961, Aldrovanda, in Hegi, Illustrierte Flora von
Mitteleuropa ed 2. IV(2a): 18-20. Carl Hanser Verlag, München.
* ^ Degreef, J.D. 1997, Fossil Aldrovanda, Carnivorous Plant
* ^ A B C D E F Cross, A. 2012. Aldrovanda, The Waterwheel Plant.
Redfern Natural History Productions, Dorset, UK, 249pp
* ^ Aston, H.I. 1983,
Aldrovanda vesiculosa L., in Flora of
Australia 8: 64-66.
* ^ Komiya, S. 1966, A report on the natural habitat of Aldrovanda