Cultivating Carnivorous Plants (2015)
Aldrovanda vesiculosa in cultivation.
The Waterwheel Plant, Aldrovanda vesiculosa, is sometimes called the Venus Flytrap of the aquatic world
for good reason. The traps of the Waterwheel Plant are nearly identical to the Venus Flytrap’s. Aldrovanda
traps are arranged in a whorl of five to nine per cross-section of plant. Each trap is two-lobed with trigger
hairs inside, much like a Venus Flytrap. Just like a Venus Flytrap, stimulation of trigger hairs by aquatic prey
causes the trap to snap shut via rapid cell growth. As the prey struggles to escape, the trap closes tighter and
releases digestive enzymes. In time,
the prey succumbs to the fluid and
is “eaten” by the plant.
Each whorl of traps is
connected to a central stem, along
which the plant grows. New trap
whorls are produced on the leading
side of the stem while old whorls die
off on the trailing side. In good
conditions, the leading edge will
split, causing the plant to branch. In
time, the trailing side will catch up
to the branching side, and the plant
will then divide into two plants.
In warm summers, the plants
flower. Each plant produces up to
five flowers with white petals. Most
plants only have one flower; two or
more flowers are rare. The flowers
open above the water for only a few
short hours. After closing, the
flowers sink beneath the water to
begin seed production. The seed is
small, black, and rare. Few flowers
are pollinated successfully, and
fewer are successful at producing
seed, particularly in temperate
regions, where the temperature
Aldrovanda vesiculosa traps.1
rarely gets warm enough to induce
During the winter, plants in temperate regions form winter buds, called turions, that sink to the bottom
of the pond to await spring. If successful at sinking, the turions can withstand temperatures down to 5° F (-
15° C). Most turions, however, are not correctly formed. Of those that are correctly formed, not all will sink.
This failure to sink results in most turions being eaten by waterfowl or killed by frost.
Similar to the Venus Flytrap, only one species of Aldrovanda, vesiculosa is currently in existence. Fossil
records reveal, however, that up to 19 different species were once in existence, although it is not currently
known if any of those evolved into Aldrovanda vesiculosa. Still, despite having only one species, Aldrovanda has
managed to spread nearly worldwide, with populations stretching from Europe to Australia.
Although having a distribution from Europe to Australia, Aldrovanda has the reputation of being one of
the most challenging aquatic carnivorous plants to cultivate long-term. In the wild, it is rare, often growing in
still bodies of freshwater in the company of aquatic species of Utricularia, water lilies, and reed-like plants.
Despite this reputation, Aldrovanda has proven to be one of the most widespread of all carnivorous plant
species, growing across Europe and into Asia (including Japan before it was driven extinct there) and down
through Australia, where a rare red form is found. Aldrovanda even used to grow in the Hula Valley of Israel,
750,000 years ago.
CULTIVATING CARNIVOROUS PLANTS
Recently, Aldrovanda has been naturalized in several location in the
United States. This naturalization attempt has proven that, in favorable
conditions, Aldrovanda populations can explode. (One location in New
York State reports millions of individuals only a few years after a
handful were introduced). The difficulty, however, is in figuring out
where Aldrovanda will be successful. Ponds that appeared, upon some
inspection, to be nearly identical can see Aldrovanda successfully spread
in one, but die in another.
Empirical research has revealed that Aldrovanda grows best in 50%
Aldrovanda seed germinating.2
shade in oligotrophic lakes. Oligotrophic lakes have low-nutrient
content, resulting in low algal production and low nutrient
transformation. As a consequence, these lakes are often very clear, with high drinking-water quality. The
bottom waters of these lakes often have ample oxygen, which supports many fish species. Undoubtedly,
similar features are found in successful cultivation set-ups.
Given these requirements, it is not too surprising that
worldwide occurrences of Aldrovanda has slipped to under
100 populations in the wild, at the last count. Although areas
such as the northeastern United States and much of Europe
have largely rebounded from the effects of acid rain and
other pollutants, elsewhere, the detrimental effects of
pollution are still being felt. As a result, populations of slow-
distributing plants, such as Aldrovanda, cannot repopulate
areas rapidly without human assistance.
Although giving an exact formula for successful
cultivation of Aldrovanda is difficult, placing a thin layer of
sphagnum peat, or mud from a swamp, on the bottom of a
container topped by a thin layer of washed sand or gravel is
generally advisable. Small, reed-like plants and sedges, such
as Carex rostrata or Carex gracilis, should be planted in the
sand. A thin layer of leaf litter should be collected on the
bottom of the container. This set-up should result in a high
Rare Australian red form of Aldrovanda
carbon-dioxide (CO2) concentration, leading to low rates of
vesiculosa growing in cultivation.
decomposition and low algae content. The optimum water
depth should be about a foot (30 cm).
My standard growing guide for Aldrovanda follows:
Media: A thin layer of sphagnum peat topped by sand and a layer of leaf litter from reed-like plants
should suffice. Water should be a depth of a foot (30 cm) or so. Some experimentation may be
necessary to achieve the clear, tea-colored water in which Aldrovanda grows well.
Container Size: Containers should be fairly large but shallow. Most waterproof containers made of
plastic work well.
Feeding: Aldrovanda will naturally catch many aquatic creatures and should not be fertilized.
Temperature: Given the wide distribution of the species, it is important to know where the plants
being cultivated are originally from or under what temperature conditions they have been successfully
cultivated. Plants from tropical regions are unlikely form winter buds, or turions, and will die if
exposed to freezing temperatures, whereas more temperate plants will form winter turions and
should be exposed to cold temperatures during winter. Essentially, growers will want to match the
native temperature ranges of the native areas.
Dormancy: Dormancy is required for temperate plants but not for tropical plants. There is some
indication that plants from one region can and sometimes adapt to different conditions, but this is
difficult to do with a species as fickle as Aldrovanda.
Propagation: Although Aldrovanda can be germinated from seed or divided much like aquatic
Utricularia, it is far easier (and less risky) to wait for the plant to divide on its own. A single plant can
produce over 30 new plants via natural division in the course of a summer, if conditions are right.