Aldrovanda

Aldrovanda /ˌældrəˈvændə/ is a genus of carnivorous plants encompassing one extant species (Aldrovanda vesiculosa, the waterwheel plant) and numerous extinct taxa. The genus is named in honor of the Italian naturalist Ulisse Aldrovandi, the founder of the Botanical Garden of Bologna, Orto Botanico dell'Università di Bologna.[2] Aldrovanda vesiculosa has been reported from scattered locations in Europe, Asia, Africa, and Australia.[1][3][4][5]

Aldrovanda
Temporal range: Paleocene - Recent
Aldrovanda vesiculosa
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Order: Caryophyllales
Family: Droseraceae
Genus: Aldrovanda
L.
Synonyms[1]
  • Drosera aldrovanda F.Muell., superfluous name
  • Aldrovanda verticillata Roxb.
  • Aldrovanda generalis E.H.L.Krause

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.[6] 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 (commonly known as the Venus flytrap), 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.[7]

Extinct relatives

The extinct species are known only from fossil pollen and seeds,[8] with the exception of A. inopinata, which is also known from fossilised laminae.[9] 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.[10][11]

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 by analysis of combined nuclear and chloroplast DNA sequences.[12][13] When sequences of chloroplast DNA of Aldrovanda, Dionaea, and Drosera were analyzed alone, however, Aldrovanda and Drosera (sundews) were shown to share a most recent common ancestor.[14] It has been proposed that this discrepancy between gene trees based on nuclear and cytoplasmic DNA analyses can be explained by chloroplast capture,[14] as similar inconsistencies have been explained by this phenomenon.[15][16]

Conservation

Aldrovanda vesiculosa is listed as “Endangered” on the IUCN Red List.[17] It is native to Europe, Asia, Africa, and Australia, but is considered extinct in much of its native range, primarily due to eutrophication.[18] 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 of New York, USA, where it is being evaluated as a potentially problematic invasive species.[19]

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 zussii

Several undescribed species are also known.

The distinctions between the various named species have been criticised,[20] although SEM analysis of the seed structures seems to confirm the existence of different species.[21]

References
  1. Kew World Checklist of Selected Plant Families, Aldrovanda vesiculosa
  2. Genaust, Helmut (1976). Etymologisches Wörterbuch der botanischen Pflanzennamen ISBN 3-7643-0755-2
  3. Lee, B.C. (2009). Rare plants data book of Korea: 1-296. Korea National Arboretum
  4. Flora of China Vol. 8 Page 201 貉藻属 he zao shu Aldrovanda Linnaeus, Sp. Pl. 1: 281. 1753.
  5. Altervista Flora Italiana, Aldrovanda vesiculosa L. includes line drawing plus a European distribution map
  6. "CPN Samples". International Carnivorous Plant Society. 1997.
  7. Hodick, Dieter; Sievers, Andreas (1989). "The action potential of Dionaea muscipula Ellis". Planta. 174 (1): 8–18. doi:10.1007/BF00394867. PMID 24221411.
  8. Degreef, J.D. (1997). "Fossil Aldrovanda" (PDF). Carnivorous Plant Newsletter. 26 (3): 93–97.
  9. Schlauer, J (1997). "Fossil Aldrovanda — additions" (PDF). Carnivorous Plant Newsletter. 26 (3): 98.
  10. Heřmanová, Z.; Kvaček, J. (2010). "Late Cretaceous Palaeoaldrovanda, not seeds of a carnivorous plant, but eggs of an insect". Journal of the National Museum. Natural History Series. Prague. 179 (9): 105–118. Archived from the original on 2016-03-04. Retrieved 2012-10-17.
  11. Schlauer, J (2012). "Literature reviews". Carnivorous Plant Newsletter. 41 (3): 121.
  12. Cameron, K.M.; Wurdack, K.J.; Jobson, R.W. (2002). "Molecular evidence for the common origin of snap-traps among carnivorous plants". American Journal of Botany. 89: 1503–1509. doi:10.3732/ajb.89.9.1503. PMID 21665752.
  13. Rivadavia, F.; Kondo, K.; Kato, M.; Hasebe, M. (2003). "Phylogeny of the sundews, Drosera (Droseraceae) based on chloroplast rbcL and nuclear 18S ribosomal DNA sequences". American Journal of Botany. 90: 123–130. doi:10.3732/ajb.90.1.123. PMID 21659087.
  14. Elansary, H.O.M.; Adamec, L.; Storchova, H. (2010). "Uniformity of organellar DNA in Aldrovanda vesiculosa, an endangered aquatic carnivorous species, distributed across four continents". Aquatic Botany. 92: 214–220. doi:10.1016/j.aquabot.2009.12.002.
  15. Tsitrone, A.; Kirkpatrick, M.; Levin, D.A. (2003). "A model for chloroplast capture". Evolution. 57: 1776–1782. doi:10.1111/j.0014-3820.2003.tb00585.x.
  16. Gaskin, J.F.; Wilson, L.M. (2007). "Phylogenetic relationships among native and naturalized Hieracium (Asteraceae) in Canada and the United States based on plastid DNA sequences". Systematic Botany. 32: 478–485. doi:10.1600/036364407781179752.
  17. "The IUCN Red List of Threatened Species". IUCN Red List of Threatened Species. Retrieved 2019-12-14.
  18. Cross, A. (2012). "Aldrovanda vesiculosa, Waterwheel". IUCN Red List. Archived from the original on 2019-05-23. Retrieved December 14, 2019.
  19. Renault, Marion (2019-08-13). "This Carnivorous Plant Invaded New York. That May Be Its Only Hope". The New York Times. ISSN 0362-4331. Retrieved 2019-12-14.
  20. Friis, E.-M. 1980. Microcarpological Studies of Middle Miocene Floras of Western Denmark. Ph.D. Thesis, Aarhus Universitet, 183-186.
  21. Iakubovskaya, T.V. (1991). "Rod Aldrovanda (Droseraceae) v Plieistotsenie Bielorussii". Bot. Zhurnal. 76 (1): 109–118.
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