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The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

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Common name: waterwheel plant

Synonyms and Other Names: Aldrovanda, waterwheel, Aldrovanda verticillata Roxb., Drosera aldrovanda F. Muell., Aldrovanda generalis E.H.L. Krause.

Aldrovanda vesiculosa is the only known species of this genus.

Identification: Aldrovanda vesiculosa L., is a free-floating, rootless, carnivorous, submersed aquatic vascular plant found in nutrient-impoverished, dystrophic waters. The whorled leaf arrangement along the stem gives rise to the common name for this species.  Aldrovanda vesiculosa plants are usually less than 20 cm in total length.  Shoots are 1-2 cm in diameter and consist of 6-8 leaves in a whorl arrangement.  Leaves are generally 7-11 mm long.  Under ideal growing conditions, 1-2 new whorls can develop per day.  A single plant may contain up to 20 whorls arranged along the stem with 0.5-0.7 cm internodes (Adamec 1997; Adamec 2000; Breckpot 1997; Kaminski 1987).  As new whorls are produced at the plant apex, the oldest whorls and internodes at the base degenerate.  Under favorable conditions, the main shoots produce lateral branches at several locations along the stem that give rise to new plants.  Leaves consist of flattened petioles up to 9 mm in length ending in a trap with 4-6 bristles.  These bristles protect the trap from being triggered by non-food items like floating debris and to concentrate potential prey. 

In its temperate range, A. vesiculosa produces apical turions which serve as an overwintering propagule. In tropical regions turion formation is less common (Breckpot 1997; Cross 2013; Maldonado San Martin et al. 2003).  In late summer, small (8 mm) single flowers with five sepals and five pinkish tinged petals form on a 5-15 mm peduncle emerging from the water surface.  Each capsule that is formed generally contains an average of 6-8 seeds (Breckpot 1997). 

Plants of Eurasian origin are light green to yellow-green in color with a high concentration of plumbagin pigment.  Australian plants also contain anthocyanins in addition to plumbagin which can give the plants a rose red to purple color (Adamec 1999; Maldonado San Martin et al. 2003).

Size: Rootless floating stems up to 20 cm long (Cross 2013).

Native Range: Wide geographic range but with few occurrences in continental Europe, Asia, Africa, and Australia.  Although the species is widely distributed, there is great concern for the plants global decline.  The species has become extinct in at least 11 of 43 countries over the last century where it was known to occur naturally prompting an “Endangered” listing by the International Union for the Conservation of Nature (Cross et al. 2015).

Alaska	Hawaii	Puerto Rico & Virgin Islands	Guam Saipan

Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Ecology: Although A. vesiculosa has the capacity for rapid growth under the right growing conditions, it is significantly impaired by its stenotopic, highly restricted habitat and ecological requirements. It favors high organic matter content in water, especially that of humic acids, characteristic of dystrophic habitats (Kaminski 1987).  High concentrations of decomposing organic matter produce high levels of CO₂ which is often the most limiting factor for healthy A. vesiculosa growth (Adamec 1997; Adamec 2000; Breckpot 1997; Cross et al. 2015; Kaminski 1987).  The optimal pH range is reported to be between 5.5 and 6.5 (Adamec 1997; Kaminski 1987).  Increasingly eutrophic waters with high levels of nitrogen and phosphorous are deleterious to A. vesiculosa survival.  It is often associated with emergent plants like Typha spp., Carex spp., Phragmites spp., and other graminoids (Breckpot 1997; Cross et al. 2015; Kaminski 1987).  Zooplankton is an important and necessary requirement for optimal growth.  Plant growth rates nearly double when plants feed on zooplankton compared to unfed plants (Adamec 1997; Adamec 2000; Ellison and Gotelli 2008). 

The primary means of reproduction is vegetative, either by stem fragmentation or turion formation.  In its temperate range, the plant produces apical turions which serve as an overwintering propagule.  Warmer climate forms of A. vesiculosa will form turions if subjected to daily temperatures below 18 °C for extended periods of time (Adamec 1999).  In the warmer, more tropical areas of its range, the plant may form turions and grows as a perennial (Breckpot 1997; Maldonado San Martin et al. 2003).  Flowering mainly occurs in its tropical (warmer) distributions.  Seed viability is low.

Means of Introduction: Aldrovanda vesiculosa has been intentionally introduced into North America waters by carnivorous plant enthusiasts for hobby and in an attempt to save the species from global extinction.  The process is referred to as “managed relocation” or “assisted colonization.” Intentional introductions are known for locations in New Jersey, New York and Virginia (Floyd et al. 2015; Lamont et al. 2013).  Continued distribution is thought to be primarily downstream movement of plant material or short distance animal assisted movement of plant fragments.  Viable seed passage through waterfowl consumption has been tested and is considered unlikely (Cross et al. 2015). Plants may also be transported via boat trailers.

First introduced into private ponds by carnivorous plant growers in Virginia in the late 1980s and early 1990s.  In 1999, plants were intentionally introduced to sites in New Jersey and New York (Lamont et al. 2013).

Status: Established in New Jersey, New York, and Virginia.  In 2014, identified in a 63 ha wetland area, including at least seven ponds, at Fort A.P. Hill, Virginia (Floyd et al. 2015, Robert Floyd pers. comm. 2016), although may have been introduced prior to 2007 (Wolowski et al. 2011).

Impact of Introduction: Due to its carnivorous nature, competition with other native carnivorous submersed macrophytes, like species in the genus Utricularia, seem likely (Cross et al. 2015; Floyd et al. 2015).  However, they co-exist in Europe (Kaminski 1987).  Impacts on the aquatic invertebrate community is worthy of study.  Up to 40% of A. vesiculosa traps can contain captured prey in suitable habitats (Cross et al. 2015).  At the Fort A.P. Hill, Virginia location, some invertebrate species are considered extremely rare and could be threatened (Floyd et al. 2015).  Rare invertebrate species at the site include Nannothemis bella (Uhler) Odonata: Libellulidae; ranked Extremely Rare at the state level, and Sigara depressa (Hungerford) Heteroptera: Corixidae; ranked Very Rare to Extremely Rare at global and state levels and listed as Endangered in Virginia (Floyd et al. 2015).  Ultimate impacts to the entire food web are unknown at this time.

Remarks: Trigger hairs inside the trap activate the trap closure in as little as 0.01 seconds.  One of the fastest closing mechanism of any carnivorous trap-plant (Breckpot 1997). 

Re-introductions of A. vesiculosa to waters where it occurred naturally in Europe have had limited success (Adamec 2005).  It has been suggested that North American populations may ultimately provide better habitat than those found in its native range and may preserve the species from extinction.

References: (click for full references)

Adamec, L.  1997.  Photosynthetic characteristics of the aquatic carnivorous plant Aldrovanda vesiculosa.  Aquatic Botany 59:297-306.

Adamec, L.  1999.  The biology and cultivation of red Australian Aldrovanda vesiculosa.  Carnivorous Plant Newsletter 28:128-132.

Adamec, L.  2000.  Rootless aquatic plant Aldrovanda vesiculosa:  physiological polarity, mineral nutrition, and importance of carnivory.  Biologia Plantarum 43(1):113-119.

Adamec, L.  2005.  Ten years after the introduction of Aldrovanda vesiculosa to the Czech Republic.  Acta Botanica Gallica 152 (2):239-245.

Breckpot, C.  1997.  Aldrovanda vesiculosa:  Description, distribution, ecology and cultivation.  Carnivorous Plant Newsletter 26:73-82.

Cross, A.T.  2013.  Turion development is an ecological trait in all populations of the aquatic carnivorous plant  Aldrovanda vesiculosa (Droseraceae).  Carnivorous Plant Newsletter  42:57-61.

Cross, A.T., L.M. Skates, L. Adamec, C. M. Hammond, P.M. Sheridan, and K.W. Dixon.  2015.  Population ecology of the endangered aquatic carnivorous macrophyte Aldrovanda vesiculosa at a naturalized site in North America.  Freshwater Biology 60:1772-1783.

Ellison, A.M. and N.J. Gotelli.  2009.  Energetics and the evolution of carnivorous plants – Darwin’s ‘most wonderful plants in the world’.  Journal of Experimental Botany 60 (1):19-42.

Floyd, R.H., S. Ferrazzano, B.W. Josey, and J.R. Applegate.  2015.  Aldrovanda vesiculosa at Fort A.P. Hill, Virginia.  Castanea 80(3):211-217.

Kaminski, R.  1987.  Studies on the Ecology of Aldrovanda vesiculosa L.I. ecological differentiation of A. vesiculosa population under the influence of chemical factors in the habitat.  Ekologia Polska 35:559-590.

Krol, E., B.J. Plachno, L. Adamec, M. Stolarz, H. Dziubinska, and K. Trebacz.  2012.  Quite a few reasons for calling carnivores ‘the most wonderful plants in the world’.  Annals of Botany 109:47-64.

Lamont, E.E., R. Sivertsen, C. Doyle, and L. Adamec.  2013.  Extant populations of Aldrovanda vesiculosa (Droseraceae) in the New World.  Journal of the Torrey Botanical Society 140 (4):517-522.

Maldonado San Martin, A.P., L. Adamec, J. Suda, T.H.M. Mes, and H. Storchova.  2003.  Genetic variation within the endangered speices Aldrovanda vesiculosa (Droseraceae) as revealed by RAPD analysis.  Aquatic Botany 75:159-172.

Wolowski, K., J. Piatek, and B.J. Plachno. 2011. Algae and stomatocysts associated with carnivorous plants. First report of chrysophyte stomatocysts from Virginia, USA. Phycologia 50(5):511-519.

Other Resources:
Aldrovanda vesiculosa fact sheet - Bugwood wiki

Dr. Lubomir Adamec's profile page

Chris Doyle's Aldrovanda vesiculosa poster

Adam Cross' Aldrovanda page

Author: Thayer, D.D., and I.A. Pfingsten

Peer Review Date: 1/4/2016

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.