Aldrovanda
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''Aldrovanda'' is a
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
of
carnivorous plant Carnivorous plants are plants that derive some or most of their nutrients from trapping and consuming animals or protozoans Protozoa (singular: protozoan or protozoon; alternative plural: protozoans) are a group of single-celled eukaryot ...
s encompassing one extant species (''
Aldrovanda vesiculosa ''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 waterwheel plant) and numerous
extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...
taxa In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...
. The genus is named in honor of the Italian naturalist
Ulisse Aldrovandi Ulisse Aldrovandi (11 September 1522 – 4 May 1605) was an Italian naturalist, the moving force behind Bologna's botanical garden, one of the first in Europe. Carl Linnaeus and the comte de Buffon reckoned him the father of natural history st ...
, the founder of the Botanical Garden of Bologna,
Orto Botanico dell'Università di Bologna The Orto Botanico dell'Università di Bologna, also known as the Orto Botanico di Bologna, is a botanical garden operated by the University of Bologna. It is located at Via Irnerio, 42, 40126 Bologna, Italy, and open daily except Mondays. Establi ...
.Genaust, Helmut (1976). ''Etymologisches Wörterbuch der botanischen Pflanzennamen'' ''Aldrovanda vesiculosa'' has been reported from scattered locations in Europe, Asia, Africa, and Australia.Kew World Checklist of Selected Plant Families, ''Aldrovanda vesiculosa''
/ref>


Description

The waterwheel is a small, free floating and rootless aquatic plant, with a length of about , and whorls of about in diameter. At every the plant branches, sometimes forming offshoots. An average of 12 to 19 whorls spans the length of the plant, each with about 5 to 9 leaves, each up to long. The growth is faster than terrestrial carnivorous plants, sometimes growing about a day. In temperate regions the plant goes dormant in the winter, forming turions of about and sinking to the bottom. In tropical regions, the plant grows all year long without forming turions. The plant flourishes and produces seeds only in these warmer regions, with temperatures higher than , and produces only one flower, white or light pink, that arises above the surface. In temperate regions, the plant reproduces mostly via asexual means, producing inviable seeds or no flower at all. The leaf structure is very similar to the '' Dionaea'' (commonly known as the
Venus flytrap The Venus flytrap (''Dionaea muscipula'') is a carnivorous plant native to subtropical wetlands on the East Coast of the United States in North Carolina and South Carolina. It catches its prey—chiefly insects and arachnids—with a trapping ...
), the main difference being air chambers present in the "stem". The traps, at the end of the leaf, contains up to 6 bristles, analogous to ''Dionaea'' teeth, that prevent debris from activating the trap. Each trap contains an additional 60–80 smaller "teeth", and circa 30–40 trigger hairs inside. The speed of closing is about 0.01 to 0.02 seconds.


Trap mechanism

The trap mechanism is akin to that present in ''Dionaea'' - Darwin even named it "the miniature aquatic Dionaea". The mechanism by which the trap snaps shut involves a complex interaction between
elasticity Elasticity often refers to: *Elasticity (physics), continuum mechanics of bodies that deform reversibly under stress Elasticity may also refer to: Information technology * Elasticity (data store), the flexibility of the data model and the cl ...
,
turgor Turgor pressure is the force within the cell that pushes the plasma membrane against the cell wall. It is also called ''hydrostatic pressure'', and is defined as the pressure in a fluid measured at a certain point within itself when at equilibriu ...
and growth. In the open, untripped state, the lobes are
convex Convex or convexity may refer to: Science and technology * Convex lens, in optics Mathematics * Convex set, containing the whole line segment that joins points ** Convex polygon, a polygon which encloses a convex set of points ** Convex polytope ...
(bent outwards), but in the closed state, the lobes are
concave Concave or concavity may refer to: Science and technology * Concave lens * Concave mirror Mathematics * Concave function, the negative of a convex function * Concave polygon, a polygon which is not convex * Concave set * The concavity In ca ...
(forming a cavity). It is the rapid flipping of this bistable state that closes the trap, but the mechanism by which this occurs is still poorly understood. When the trigger hairs are stimulated, an
action potential An action potential occurs when the membrane potential of a specific cell location rapidly rises and falls. This depolarization then causes adjacent locations to similarly depolarize. Action potentials occur in several types of animal cells, ...
(mostly involving calcium ions—see
calcium in biology Calcium ions (Ca2+) contribute to the physiology and biochemistry of organisms' cell (biology), cells. They play an important role in signal transduction pathways, where they act as a second messenger, in neurotransmitter release from neurons, in ...
) is generated, which propagates across the lobes and stimulates cells in the lobes and in the
midrib This glossary of botanical terms is a list of definitions of terms and concepts relevant to botany and plants in general. Terms of plant morphology are included here as well as at the more specific Glossary of plant morphology and Glossary o ...
between them.


Extinct relatives

The extinct species are known only from
fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
pollen Pollen is a powdery substance produced by seed plants. It consists of pollen grains (highly reduced microgametophytes), which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects the gametophyt ...
and
seed A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiospe ...
s, with the exception of ''A. inopinata'', which is also known from fossilised laminae. ''Aldrovanda'' was for a long time thought to be related to the
Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...
form taxon Form classification is the classification of organisms based on their morphology, which does not necessarily reflect their biological relationships. Form classification, generally restricted to palaeontology, reflects uncertainty; the goal of sc ...
'' Palaeoaldrovanda splendens'', but research published in 2010 suggests that remains attributed to ''Palaeoaldrovanda'' actually represent fossilised
insect egg An egg is an organic vessel grown by an animal to carry a possibly fertilized egg cell (a zygote) and to incubate from it an embryo within the egg until the embryo has become an animal fetus that can survive on its own, at which point the a ...
s.


Evolution

The organ of carnivory in ''Aldrovanda'' is the snap trap. Snap traps are only found in one other carnivorous plant genus, ''Dionaea''. The two genera have been shown to share a
most recent common ancestor In biology and genetic genealogy, the most recent common ancestor (MRCA), also known as the last common ancestor (LCA) or concestor, of a set of organisms is the most recent individual from which all the organisms of the set are descended. The ...
by analysis of combined
nuclear Nuclear may refer to: Physics Relating to the nucleus of the atom: * Nuclear engineering *Nuclear physics *Nuclear power *Nuclear reactor *Nuclear weapon *Nuclear medicine *Radiation therapy *Nuclear warfare Mathematics *Nuclear space *Nuclear ...
and
chloroplast DNA Chloroplast DNA (cpDNA) is the DNA located in chloroplasts, which are photosynthetic organelles located within the cells of some eukaryotic organisms. Chloroplasts, like other types of plastid, contain a genome separate from that in the cell nu ...
sequences. When sequences of chloroplast DNA of ''Aldrovanda'', ''Dionaea'', and ''Drosera'' were analyzed alone, however, ''Aldrovanda'' and ''
Drosera ''Drosera'', which is commonly known as the sundews, is one of the largest genus, genera of carnivorous plants, with at least 194 species. 2 volumes. These members of the family Droseraceae lure, capture, and digest insects using stalked mucil ...
'' (sundews) were shown to share a most recent common ancestor. It has been proposed that this discrepancy between gene trees based on nuclear and cytoplasmic DNA analyses can be explained by
chloroplast capture Chloroplast capture is an evolutionary process through which inter-species Hybrid (biology), hybridization and subsequent backcrossing, backcrosses yield a plant with new genetic combination of nuclear and chloroplast genomes. For instance, 1) speci ...
, as similar inconsistencies have been explained by this phenomenon.


Conservation

''Aldrovanda vesiculosa'' is listed as “Endangered” on the
IUCN Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biol ...
. It is native to Europe, Asia, Africa, and Australia, but is considered extinct in much of its native range, primarily due to
eutrophication Eutrophication is the process by which an entire body of water, or parts of it, becomes progressively enriched with minerals and nutrients, particularly nitrogen and phosphorus. It has also been defined as "nutrient-induced increase in phytopla ...
. Despite being endangered in its native range, it was introduced in the U.S. and has been reported to be rapidly spreading in the waters of the
Catskill Mountains The Catskill Mountains, also known as the Catskills, are a physiographic province of the larger Appalachian Mountains, located in southeastern New York. As a cultural and geographic region, the Catskills are generally defined as those areas c ...
of New York, USA, where it is being evaluated as a potentially problematic
invasive species An invasive species otherwise known as an alien is an introduced organism that becomes overpopulated and harms its new environment. Although most introduced species are neutral or beneficial with respect to other species, invasive species ad ...
.


Species

*†''Aldrovanda borysthenica'' *†''Aldrovanda clavata'' *†''Aldrovanda dokturovskyi'' *†''Aldrovanda eleanorae'' *†''Aldrovanda europaea'' *†''Aldrovanda inopinata'' *†''Aldrovanda intermedia'' *†''Aldrovanda kuprianovae'' *†''Aldrovanda megalopolitana'' *†''Aldrovanda nana'' *†''Aldrovanda ovata'' *†''Aldrovanda praevesiculosa'' *†''Aldrovanda rugosa'' *†''Aldrovanda sibirica'' *†''Aldrovanda sobolevii'' *†''Aldrovanda unica'' *''
Aldrovanda vesiculosa ''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 ...
'' *†''Aldrovanda zussii'' Several undescribed species are also known. The distinctions between the various named species have been criticised, although SEM analysis of the seed structures seems to confirm the existence of different species.


References

{{Taxonbar, from=Q19668 Droseraceae Flora of Asia Flora of Europe Flora of Africa Extant Paleocene first appearances