Aquatic plant
Overview
Aquatic plants are plants that have adapted to living in aquatic environments. They are also referred to as hydrophytes or aquatic macrophytes. These plants require special adaptations for living submerged in water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...

, or at the water's surface. Aquatic plants can only grow in water or in soil
Soil
Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...

 that is permanently saturated with water. Aquatic vascular plant
Vascular plant
Vascular plants are those plants that have lignified tissues for conducting water, minerals, and photosynthetic products through the plant. Vascular plants include the clubmosses, Equisetum, ferns, gymnosperms and angiosperms...

s can be fern
Fern
A fern is any one of a group of about 12,000 species of plants belonging to the botanical group known as Pteridophyta. Unlike mosses, they have xylem and phloem . They have stems, leaves, and roots like other vascular plants...

s or angiosperms (from a variety of families, including monocots and dicots).
Encyclopedia
Aquatic plants are plants that have adapted to living in aquatic environments. They are also referred to as hydrophytes or aquatic macrophytes. These plants require special adaptations for living submerged in water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...

, or at the water's surface. Aquatic plants can only grow in water or in soil
Soil
Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...

 that is permanently saturated with water. Aquatic vascular plant
Vascular plant
Vascular plants are those plants that have lignified tissues for conducting water, minerals, and photosynthetic products through the plant. Vascular plants include the clubmosses, Equisetum, ferns, gymnosperms and angiosperms...

s can be fern
Fern
A fern is any one of a group of about 12,000 species of plants belonging to the botanical group known as Pteridophyta. Unlike mosses, they have xylem and phloem . They have stems, leaves, and roots like other vascular plants...

s or angiosperms (from a variety of families, including monocots and dicots). Seaweed
Seaweed
Seaweed is a loose, colloquial term encompassing macroscopic, multicellular, benthic marine algae. The term includes some members of the red, brown and green algae...

s are not vascular plants; rather they are multicellular marine
Ocean
An ocean is a major body of saline water, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas.More than half of this area is over 3,000...

 algae
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...

, and therefore are not typically included among aquatic plants. As opposed to plant types such as mesophyte
Mesophyte
Mesophytes are terrestrial plants which are adapted to neither a particularly dry nor particularly wet environment. An example of a mesophytic habitat would be a rural temperate meadow, which might contain Goldenrod, Clover, Oxeye Daisy, and Rosa multiflora.Mesophytes make up the largest ecological...

s and xerophyte
Xerophyte
A xerophyte or xerophytic organism is a plant which has adapted to survive in an environment that lacks water, such as a desert. Xerophytic plants may have adapted shapes and forms or internal functions that reduce their water loss or store water during long periods of dryness...

s, hydrophytes do not have a problem retaining water, due to the abundance of water in their environment. This means that aquatic plants have less need to regulate transpiration
Transpiration
Transpiration is a process similar to evaporation. It is a part of the water cycle, and it is the loss of water vapor from parts of plants , especially in leaves but also in stems, flowers and roots. Leaf surfaces are dotted with openings which are collectively called stomata, and in most plants...

, which would require more energy and be of little benefit to the plant.

Characteristics of aquatic plants:
  • A thin cuticle
    Plant cuticle
    Plant cuticles are a protective waxy covering produced only by the epidermal cells of leaves, young shoots and all other aerial plant organs without periderm...

    . Thick cuticles reduce water loss; thus most hydrophytes have no need for thick cuticles.
  • Stomata that are open most of the time, because water is abundant and there is no need for it to be retained in the plant. This means that guard cells on the stomata are generally inactive.
  • An increased number of stomata, which can be on either side of the leaves.
  • A less rigid structure: water pressure supports them.
  • Flat leaves
    Leaf
    A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....

     on surface plants for flotation.
  • Air sacs for flotation.
  • Smaller root
    Root
    In vascular plants, the root is the organ of a plant that typically lies below the surface of the soil. This is not always the case, however, since a root can also be aerial or aerating . Furthermore, a stem normally occurring below ground is not exceptional either...

    s: water can diffuse
    Diffusion
    Molecular diffusion, often called simply diffusion, is the thermal motion of all particles at temperatures above absolute zero. The rate of this movement is a function of temperature, viscosity of the fluid and the size of the particles...

     directly into leaves; thus large root systems are not required for water uptake.
  • Feathery roots: no need to support the plant.
  • Specialized roots able to take in oxygen.


For example, some species of buttercup (genus Ranunculus
Ranunculus
Ranunculus is a large genus of about 600 species of plants in the Ranunculaceae. Members of the genus include the buttercups, spearworts, water crowfoots and the lesser celandine....

) float slightly submerged in water; only the flowers extend above the water. Their leaves and roots are long and thin and almost hair-like; this helps spread the mass
Mass
Mass can be defined as a quantitive measure of the resistance an object has to change in its velocity.In physics, mass commonly refers to any of the following three properties of matter, which have been shown experimentally to be equivalent:...

 of the plant over a wide area, making it more buoyant
Buoyancy
In physics, buoyancy is a force exerted by a fluid that opposes an object's weight. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus a column of fluid, or an object submerged in the fluid, experiences greater pressure at the bottom of the...

. Long roots and thin leaves also provide a greater surface area for uptake of mineral
Mineral
A mineral is a naturally occurring solid chemical substance formed through biogeochemical processes, having characteristic chemical composition, highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not...

 solutes and oxygen.

Wide flat leaves in water lilies (family Nymphaeaceae
Nymphaeaceae
Nymphaeaceae is a family of flowering plants. Members of this family are commonly called water lilies and live in freshwater areas in temperate and tropical climates around the world. The family contains eight genera. There are about 70 species of water lilies around the world. The genus...

) help distribute weight over a large area, thus helping them float near surface.

Many fish keepers keep aquatic plants in their tanks to control phytoplankton
Phytoplankton
Phytoplankton are the autotrophic component of the plankton community. The name comes from the Greek words φυτόν , meaning "plant", and πλαγκτός , meaning "wanderer" or "drifter". Most phytoplankton are too small to be individually seen with the unaided eye...

 and moss
Moss
Mosses are small, soft plants that are typically 1–10 cm tall, though some species are much larger. They commonly grow close together in clumps or mats in damp or shady locations. They do not have flowers or seeds, and their simple leaves cover the thin wiry stems...

 by removing metabolites.

Many species of aquatic plant are invasive species
Invasive species
"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....

. Aquatic plants make particularly good weed
Weed
A weed in a general sense is a plant that is considered by the user of the term to be a nuisance, and normally applied to unwanted plants in human-controlled settings, especially farm fields and gardens, but also lawns, parks, woods, and other areas. More specifically, the term is often used to...

s because they reproduce vegetatively
Vegetative reproduction
Vegetative reproduction is a form of asexual reproduction in plants. It is a process by which new individuals arise without production of seeds or spores...

 from fragments.

Adaptations

  • Floating plants: In an outdoor body of water, these receive more sunlight than submerged plants do. They also rarely have to compete with one another for sunlight
  • Submerged plants: The leaves of submerged plants receive lower levels of sunlight because light energy diminishes while passing through a water column.

----
All floating plants
  • Either have air spaces trapped in their roots, or else air spaces in their bodies (aerenchyma
    Aerenchyma
    Aerenchyma is an air channel in the roots of some plants, which allows exchange of gases between the shoot and the root. The channel of large air-filled cavities provides a low-resistance internal pathway for the exchange of gases such as oxygen and ethylene between the plant above the water and...

    ) to help them to float, thus receiving adequate sunshine
  • Have hair on their leaves that traps air
  • Structural adaptations
  • Have hollow stems to float on water.

----
Duckweed, water cabbage
  • Chloroplast found on the top surface of the leaves
  • Upper Surface has a thick, waxy cuticle to repel water and to help keep the stomata open and clear
  • Structural adaptation
  • Small and light

----
Water lily
Nymphaeaceae
Nymphaeaceae is a family of flowering plants. Members of this family are commonly called water lilies and live in freshwater areas in temperate and tropical climates around the world. The family contains eight genera. There are about 70 species of water lilies around the world. The genus...

  • Structural material to reach higher points and receive more sunlight
  • Structural adaptation

----
Floating heart, water lily
Nymphaeaceae
Nymphaeaceae is a family of flowering plants. Members of this family are commonly called water lilies and live in freshwater areas in temperate and tropical climates around the world. The family contains eight genera. There are about 70 species of water lilies around the world. The genus...

, lotus
Nelumbo
Nelumbo is a genus of aquatic plants with large, showy flowers resembling water lilies, commonly known as lotus. The generic name is derived from the Sinhalese word Nelum. There are only two known living species in the genus. The sacred lotus is native to Asia, and is the better known of the two...

, yellow pond lily
Nuphar lutea
Nuphar lutea is an aquatic plant of the family Nymphaeaceae, native to temperate regions of Europe, northwest Africa, and western Asia.-Growth:...

, water-shield
Water-shield
Water-shield may refer to following aquatic plants:* Brasenia schreberi * Cabomba caroliniana...

  • Their leaves tend to be broader without major lobing, to remain flat on water surface, to enlarge their surface area, and to make use of as much sunlight as possible. Their chloroplasts are found on the tops of their leaves.
  • Structural/ behavioral adaptations

----
Most partially-submerged ("emersed") plants
  • Air spaces within their tissues to keep them buoyant so that their leaves can reach the top of the body of water, in order to receive an adequate amount of sunlight
  • Structural adaptation

----
Dissected: Parrot's Feather, Hornwort
Hornwort
Hornworts are a group of bryophytes, or non-vascular plants, comprising the division Anthocerotophyta. The common name refers to the elongated horn-like structure, which is the sporophyte. The flattened, green plant body of a hornwort is the gametophyte plant.Hornworts may be found worldwide,...



Thread-like: ditch-grass, quillwort
Quillwort
Isoëtes, also written Isoetes and commonly known as the quillworts, is a genus of plants in the class Isoetopsida and order Isoetales. They are considered "fern allies". There are about 140-150 species, with a cosmopolitan distribution but often scarce to rare...

  • Highly dissected/ divided leaves or thread-like ones, allows for a bigger surface area (surface to volume ratio)
  • Structural adaptation

----
Hydrilla
Hydrilla
Hydrilla is an aquatic plant genus, usually treated as containing just one species, Hydrilla verticillata, though some botanists divide it into several species. Synonyms include H. asiatica, H. japonica, H. lithuanica, and H. ovalifolica...

  • Elongates rapidly to reach water surface and branches out at water surface; more light can be obtained at water surface
  • Structural/ behavioral adaptation
  • Xylem tubes are absent

Human nutrition

Many aquatic plants are used by humans as a food source. Note that especially in (South-east) Asia edible but uncooked hydrophytes are implicated in the transmission of fasciolopsiasis
Fasciolopsiasis
Fasciolopsiasis results from an infection by the trematode Fasciolopsis buski, the largest intestinal fluke of humans .-Infection cycle:...

.
See also Fasciola hepatica
Fasciola hepatica
Fasciola hepatica, also known as the common liver fluke or sheep liver fluke, is a parasitic flatworm of the class Trematoda, phylum Platyhelminthes that infects the livers of various mammals, including humans. The disease caused by the fluke is called fascioliasis . F...

.
  • Wild rice (Zizania)
  • Water caltrop (Trapa natans)
  • Chinese water chestnut (Eleocharis dulcis
    Eleocharis dulcis
    The Chinese water chestnut , more often called simply the water chestnut, is a grass-like sedge grown for its edible corms. The water chestnut is actually not a nut at all, but an aquatic vegetable that grows in marshes, underwater in the mud...

    )
  • Indian Lotus (Nelumbo nucifera
    Nelumbo nucifera
    Nelumbo nucifera, known by a number of names including Indian Lotus, Sacred Lotus, Bean of India, or simply Lotus, is a plant in the monogeneric family Nelumbonaceae...

    )
  • Water spinach (Ipomoea aquatica
    Ipomoea aquatica
    Ipomoea aquatica is a semi-aquatic tropical plant grown as a leaf vegetable. It is known in English as Water Spinach, Water Morning Glory, Water Convolvulus, or by the more ambiguous names "Chinese spinach" and "swamp cabbage". It has many other names in other languages, such as "Phak bung" in Thai...

    )
  • Watercress (Rorippa nasturtium-aquaticum)
  • Water mimosa (Neptunia natans)
  • Taro (Colocasia esculenta
    Colocasia esculenta
    Colocasia esculenta is a tropical plant grown primarily for its edible corms, the root vegetables whose many names include Taro and Eddoe. It is believed to be one of the earliest cultivated plants.-Description:Rhizomes of different shapes and sizes...

    )
  • Rice (Oryza
    Oryza
    Oryza is a genus of seven to twenty species of grasses in the tribe Oryzeae, within the subfamily Bambusoideae, native to tropical and subtropical regions of Asia, Northern Australia and Africa...

    ) is originally not an aquatic plant.
  • Bulrush, reedmace, or cattail (Typha
    Typha
    Typha is a genus of about eleven species of monocotyledonous flowering plants in the family Typhaceae. The genus has a largely Northern Hemisphere distribution, but is essentially cosmopolitan, being found in a variety of wetland habitats...

    )
  • Water-pepper (Polygonum hydropiper)
  • Wasabi (Wasabia japonica)
  • Kjosco
    Fascioliasis
    Fasciolosis also known as Fascioliasis, Fasciolasis, distomatosis and liver rot, is an important helminth disease caused by two trematodes Fasciola hepatica and Fasciola gigantica. This disease belongs to the plant-borne trematode zoonoses. In Europe, the Americas and Oceania only F...

  • Totora (Scirpus californicus)

Animal nutrition

Some examples of aquatic plants
  • Water hyacinth
    Water hyacinth
    The seven species of water hyacinth comprise the genus Eichhornia. Water hyacinth are a free-floating perennial aquatic plant native to tropical and sub-tropical South America. With broad, thick, glossy, ovate leaves, water hyacinth may rise above the surface of the water as much as 1 meter in...

     (Eichhornia)
  • Duckweed: Lemna
    Lemna
    Lemna is a genus of free-floating aquatic plants from the duckweed family. These rapidly-growing plants have found uses as a model system for studies in community ecology, basic plant biology, in ecotoxicology, in production of biopharmaceuticals, and as a source of animal feeds for agriculture...

    , Spirodela
    Spirodela
    Spirodela is a genus of aquatic plant. It is one of several genera containing plants commonly called duckweed. Spirodela species are members of the Araceae under the APG II system. They were formerly members of the Lemnaceae....

     and Wolffia
    Wolffia
    Wolffia is a genus of 9 to 11 species which include the smallest flowering plants on Earth. Commonly called watermeal or duckweed, these aquatic plants resemble specks of cornmeal floating on the water. Wolffia species are free-floating thalli, green or yellow-green, and without roots. The flower...

  • Trichanthera gigantea

Some examples of aquatic plants

  • Most algae
    Algae
    Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...

    , and all seaweed
    Seaweed
    Seaweed is a loose, colloquial term encompassing macroscopic, multicellular, benthic marine algae. The term includes some members of the red, brown and green algae...

     and kelp
    Kelp
    Kelps are large seaweeds belonging to the brown algae in the order Laminariales. There are about 30 different genera....

  • Riella
    Riella
    Riella is the only genus in the liverwort family Riellaceae, and includes about eighteen species. Plants in the genus are small and grow submerged in shallow temporary pools. Although the genus is widely distributed in the Northern Hemisphere, locating populations is often difficult. Its...

    , the only genus of liverwort to grow as a submerged aquatic.
  • Utricularia (from the Latin, utriculus, a little bag or bottle) is a genus of slender aquatic plants, the leaves of which contain floating air bladders. They are called bladderwort
    Bladderwort
    Utricularia, commonly and collectively called the bladderworts, is a genus of carnivorous plants consisting of approximately 233 species . They occur in fresh water and wet soil as terrestrial or aquatic species across every continent except Antarctica...

    s.
  • Water lettuce

See also

  • Aqua Planta
    Aqua Planta
    Aqua Planta is a German magazine covering aquatic plants and plants cultivated in aquariums. It is the official magazine of the "Arbeitskreis Wasserpflanzen" of the "Verband Deutscher Verine für Aquarien- und Terrarienkunde"...

  • Aquascaping
    Aquascaping
    Aquascaping is the craft of arranging aquatic plants, as well as rocks, stones, cavework, or driftwood, in an aesthetically pleasing manner within an aquarium—in effect, gardening under water. Aquascape designs include a number of distinct styles, including the garden-like Dutch style and the...

  • Aquatic animal
    Aquatic animal
    An aquatic animal is an animal, either vertebrate or invertebrate, which lives in water for most or all of its life. It may breathe air or extract its oxygen from that dissolved in water through specialised organs called gills, or directly through its skin. Natural environments and the animals that...

  • Aquatic Botany
    Aquatic Botany
    Aquatic Botany is a peer-reviewed scientific journal dedicated to research on structure, function, dynamics, and classification of plant-dominated aquatic communities and ecosystems, as well as molecular, biochemical, and...

  • Bog
    Bog
    A bog, quagmire or mire is a wetland that accumulates acidic peat, a deposit of dead plant material—often mosses or, in Arctic climates, lichens....

  • Commercial production of aquatic plants
  • Helophyte
    Helophyte
    A helophyte or limnodophyte is the phytosociologic definition of a biennial or herbaceous plant of which only the buds survive a harsh period, such as winter, e.g. sweet flag or bulrush ....

  • List of freshwater aquarium plant species
  • Marsh
    Marsh
    In geography, a marsh, or morass, is a type of wetland that is subject to frequent or continuous flood. Typically the water is shallow and features grasses, rushes, reeds, typhas, sedges, other herbaceous plants, and moss....

  • Paddy field
    Paddy field
    A paddy field is a flooded parcel of arable land used for growing rice and other semiaquatic crops. Paddy fields are a typical feature of rice farming in east, south and southeast Asia. Paddies can be built into steep hillsides as terraces and adjacent to depressed or steeply sloped features such...

  • Salt marsh
    Salt marsh
    A salt marsh is an environment in the upper coastal intertidal zone between land and salt water or brackish water, it is dominated by dense stands of halophytic plants such as herbs, grasses, or low shrubs. These plants are terrestrial in origin and are essential to the stability of the salt marsh...

  • Sea grass
  • Swamp gas
  • Xerophyte
    Xerophyte
    A xerophyte or xerophytic organism is a plant which has adapted to survive in an environment that lacks water, such as a desert. Xerophytic plants may have adapted shapes and forms or internal functions that reduce their water loss or store water during long periods of dryness...



Source

  • Cook, C.D.K. (ed). 1974. Water Plants of the World. Dr W Junk Publishers, The Hague. ISBN 90-6193-024-3

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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