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ALDROVANDA /ældrəˈvændə/ is a genus of carnivorous plants encompassing one extant species ( Aldrovanda vesiculosa
Aldrovanda vesiculosa
, the waterwheel plant) and numerous extinct taxa . The genus is named in honor of the Italian naturalist Ulisse Aldrovandi
Ulisse Aldrovandi
, the founder of the Botanical Garden of Bologna, Orto Botanico dell\'Università di Bologna . Aldrovanda vesiculosa
Aldrovanda vesiculosa
has been reported from scattered locations in Europe, Asia, Africa, and Australia.

CONTENTS

* 1 Description

* 1.1 Trap mechanism

* 2 Extinct relatives * 3 Evolution * 4 Species * 5 References

DESCRIPTION

The waterwheel is a small, free floating and rootless aquatic plant, with a length of about 1.5 to 20 cm (9⁄16 to 7 7⁄8 in), and whorls of about 1 to 2 cm (3⁄8 to 13⁄16 in) in diameter. At every 3 to 4 cm (1 3⁄16 to 1 9⁄16 in) 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 11 mm (7⁄16 in) long. The growth is faster than terrestrial carnivorous plants, sometimes growing about 4 to 9 mm (3⁄16 to 3⁄8 in) a day.

In temperate regions the plant goes dormant in the winter, forming turions of about 4–6 mm (3⁄16–1⁄4 in) 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 25 °C (77 °F), 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, the main difference being air chambers present in the "stem". The traps, at the end of the leaf, contains up to 6 bristles, analog to the Dionaea teeths, that prevents debris from activating the trap. Each trap contains 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 , turgor and growth. In the open, untripped state, the lobes are convex (bent outwards), but in the closed state, the lobes are concave (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 (mostly involving calcium ions—see calcium in biology ) is generated, which propagates across the lobes and stimulates cells in the lobes and in the midrib between them.

EXTINCT RELATIVES

The extinct species are known only from fossil pollen and seeds , with the exception of A. inopinata, which is also known from fossilised laminae . Aldrovanda
Aldrovanda
was for a long time thought to be related to the Late Cretaceous form taxon Palaeoaldrovanda splendens , but research published in 2010 suggests that remains attributed to Palaeoaldrovanda actually represent fossilised insect eggs .

EVOLUTION

The organ of carnivory in Aldrovanda
Aldrovanda
is the snap trap . Snap traps are only found in one other carnivorous plant genus, Dionaea , which comprises the commonly known Venus flytrap. Aldrovanda
Aldrovanda
and Dionaea have been shown to share a most recent common ancestor by analysis of combined nuclear and chloroplast DNA sequences. When sequences of chloroplast DNA of Aldrovanda, Dionaea, and Drosera
Drosera
were analyzed alone, however, Aldrovanda
Aldrovanda
and Drosera
Drosera
(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 , as similar inconsistencies have been explained by this phenomenon.

SPECIES

* † Aldrovanda
Aldrovanda
borysthenica * † Aldrovanda
Aldrovanda
clavata * † Aldrovanda
Aldrovanda
dokturovskyi * † Aldrovanda
Aldrovanda
eleanorae * † Aldrovanda
Aldrovanda
europaea * † Aldrovanda
Aldrovanda
inopinata * † Aldrovanda
Aldrovanda
intermedia * † Aldrovanda
Aldrovanda
kuprianovae * † Aldrovanda
Aldrovanda
megalopolitana * † Aldrovanda
Aldrovanda
nana * † Aldrovanda
Aldrovanda
ovata * † Aldrovanda
Aldrovanda
praevesiculosa * † Aldrovanda
Aldrovanda
rugosa * † Aldrovanda
Aldrovanda
sibirica * † Aldrovanda
Aldrovanda
sobolevii * † Aldrovanda
Aldrovanda
unica * Aldrovanda vesiculosa
Aldrovanda vesiculosa
* † Aldrovanda
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

* ^ A B Kew World Checklist of Selected Plant
Plant
Families, Aldrovanda vesiculosa * ^ Genaust, Helmut (1976). Etymologisches Wörterbuch der botanischen Pflanzennamen ISBN 3-7643-0755-2 * ^ Lee, B.C. (2009). Rare plants data book of Korea: 1-296. Korea National Arboretum * ^ Flora of China Vol. 8 Page 201 貉藻属 HE ZAO SHU ALDROVANDA LINNAEUS, SP. PL. 1: 281. 1753. * ^ Altervista Flora Italiana, Aldrovanda vesiculosa
Aldrovanda vesiculosa
L. includes line drawing plus a European distribution map * ^ "CPN Samples". International Carnivorous Plant
Plant
Society. 1997. * ^ Hodick, Dieter; Sievers, Andreas (1989). "The action potential of Dionaea muscipula
Dionaea muscipula
Ellis". Planta. 174 (1): 8–18. doi :10.1007/BF00394867 . * ^ Degreef, J.D. 1997. " Fossil
Fossil
Aldrovanda" (PDF). Carnivorous Plant
Plant
Newsletter 26(3): 93–97. * ^ Schlauer, J. 1997. " Fossil
Fossil
Aldrovanda
Aldrovanda
— additions" (PDF). Carnivorous Plant
Plant
Newsletter 26(3): 98. * ^ Heřmanová, Z. ">

* v * t * e

Carnivorous and protocarnivorous plants

Carnivorous genera († extinct)

* Aldrovanda * † Archaeamphora * Brocchinia * Byblis * Catopsis * Cephalotus * Darlingtonia * Dionaea * Drosera
Drosera
* † Droserapites * † Droserapollis * † Droseridites
Droseridites
* Drosophyllum
Drosophyllum
* † Fischeripollis
Fischeripollis
* Genlisea * Heliamphora * Nepenthes * † Palaeoaldrovanda * Philcoxia * Pinguicula * Roridula * Sarracenia * † Saxonipollis * Triphyophyllum * Utricularia

PROTOCARNIVOROUS GENERA

* Aracamunia * Capsella * Colura * Dipsacus * Drymocallis * Geranium * Ibicella * Lathraea
Lathraea
* Paepalanthus * Passiflora