Aquatic plants are plants that have adapted to living in aquatic environments (saltwater or freshwater). They are also referred to as hydrophytes or macrophytes. A macrophyte is an aquatic plant that grows in or near water and is either emergent, submergent, or floating, and includes helophytes (a plant that grows in marsh, partly submerged in water, so that it regrows from buds below the water surface). In lakes and rivers macrophytes provide cover for fish and substrate for aquatic invertebrates, produce oxygen, and act as food for some fish and wildlife.
Aquatic plants require special adaptations for living submerged in water, or at the water's surface. The most common adaptation is aerenchyma, but floating leaves and finely dissected leaves are also common. Aquatic plants can only grow in water or in soil that is permanently saturated with water. They are therefore a common component of wetlands.
Fringing stands of tall vegetation by water basins and rivers may include helophytes. Examples include stands of Equisetum fluviatile, Glyceria maxima, Hippuris vulgaris, Sagittaria, Carex, Schoenoplectus, Sparganium, Acorus, yellow flag (Iris pseudacorus), Typha and Phragmites australis.
The principal factor controlling the distribution of aquatic plants is the depth and duration of flooding. However, other factors may also control their distribution, abundance, and growth form, including nutrients, disturbance from waves, grazing, and salinity.
Aquatic vascular plants have originated on multiple occasions in different plant families; they can be ferns or angiosperms (including both monocots and dicots). Seaweeds are not vascular plants; rather they are multicellular marine algae, and therefore are not typically included among aquatic plants. A few aquatic plants are able to survive in brackish, saline, and salt water. The only angiosperms capable of growing completely submerged in seawater are the seagrasses. Examples are found in genera such as Thalassia and Zostera. Although most aquatic plants can reproduce by flowering and setting seed, many also have extensive asexual reproduction by means of rhizomes, turions, and fragments in general.
One of the largest aquatic plants in the world is the Amazon water lily; one of the smallest is the minute duckweed. Many small aquatic animals use plants like duckweed for a home, or for protection from predators, but areas with more vegetation are likely to have more predators. Some other familiar examples of aquatic plants might include floating heart, water lily, lotus, and water hyacinth.
Based on growth form, macrophytes can be classified as:
An emergent plant is one which grows in water but which pierces the surface so that it is partially in air. Collectively, such plants are emergent vegetation.
This habit may have developed because the leaves can photosynthesize more efficiently above the shade of cloudy water and competition from submerged plants but often, the main aerial feature is the flower and the related reproductive process. The emergent habit permits pollination by wind or by flying insects.
There are many species of emergent plants, among them, the reed (Phragmites), Cyperus papyrus, Typha species, flowering rush and wild rice species. These may be found growing in fens but usually less well owing to competition from other plants. Some species, such as purple loosestrife, may grow in water as emergent plants but they are capable of flourishing in fens or simply in damp ground.
Floating-leaved macrophytes have root systems attached to the substrate or bottom of the body of water and with leaves that float on the water surface. Common floating leaves macrophytes are water lilies (family Nymphaeaceae), pondweeds (family Potamogetonaceae).
Submerged macrophytes completely grow under water with root attached to the substrate (e.g. Myriophyllum spicatum) or without any root system (e.g. Ceratophyllum demersum).
Free-floating macrophytes are aquatic plants that are found suspended on water surface with their root not attached to substrate or sediment or bottom of water body. They are easily blown by air and provide breeding ground for mosquito. Example include Pistia spp commonly called water lettuce, water cabbage or Nile cabbage
Macrophytes perform many ecosystem functions in aquatic ecosystems and provide services to human society. One of the important functions performed by macrophyte is uptake of dissolve nutrients (N and P) from water. Macrophytes are widely used in constructed wetlands around the world to remove excess N and P from polluted water. Beside direct nutrient uptake, macrophytes indirectly influence nutrient cycling, especially N cycling through influencing the denitrifying bacterial functional groups that are inhabiting on roots and shoots of macrophytes. Macrophytes promote the sedimentation of suspended solids by reducing the current velocities, impede erosion by stabilising soil surfaces. Macrophytes also provide spatial heterogeneity in otherwise unstructured water column. Habitat complexity provided by macrophytes like to increase the richness of taxonomy and density of both fish and invertebrates.
Some aquatic plants are used by humans as a food source. Examples include wild rice (Zizania), water caltrop (Trapa natans), Chinese water chestnut (Eleocharis dulcis), Indian lotus (Nelumbo nucifera), water spinach (Ipomoea aquatica), and watercress (Rorippa nasturtium-aquaticum).
A decline in a macrophyte community may indicate water quality problems and changes in the ecological status of the water body. Such problems may be the result of excessive turbidity, herbicides, or salinization. Conversely, overly high nutrient levels may create an overabundance of macrophytes, which may in turn interfere with lake processing.
Macrophyte levels are easy to sample, do not require laboratory analysis, and are easily used for calculating simple abundance metrics.
Phytochemical and pharmacological researches suggest that freshwater macrophytes, such as Centella asiatica, Nelumbo nucifera, Nasturtium officinale, Ipomoea aquatica and Ludwigia adscendens, are promising sources of anticancer and antioxidative natural products.
Hot water extracts of the stem and root of Ludwigia adscendens, as well as those of the fruit, leaf and stem of Monochoria hastata were found to have lipoxygenase inhibitory activity. Hot water extract prepared from the leaf of Ludwigia adscendens exhibits alpha-glucosidase inhibitory activity more potent than that of acarbose.
Armatimonadetes is a phylum of gram-negative bacteria.Cross Creeks National Wildlife Refuge
Cross Creeks National Wildlife Refuge is a part of the U.S. system of National Wildlife Refuges located along the Lake Barkley impoundment of the Cumberland River in Stewart County, Tennessee near Dover, covering 8,862 acres (35.86 km2). It provides habitat for a wide variety of waterfowl and aquatic plant life in what is a largely wetlands environment. Cross Creeks is the only National Wildlife Refuge located entirely in Middle Tennessee as of 2006.Eichhornia crassipes
Eichhornia crassipes, commonly known as common water hyacinth, is an aquatic plant native to the Amazon basin, and is often a highly problematic invasive species outside its native range.Herstmonceux Park
Herstmonceux Park is a 4.3-hectare (11-acre) biological Site of Special Scientific Interest south of Herstmonceux in East Sussex.This narrow stream valley has seven examples of wetland habitats on Tunbridge Wells sandstone and it is notable for its fen vegetation. The site is the location of two plants which are rare in south-east England, milk-parsley and Cornish moneywort. There are several artificial ponds which have a variety of aquatic plant species.A public footpath runs through the siteHippuris vulgaris
Hippuris vulgaris (from Greek: ἵππος — horse and οὐρά — tail), known as mare's-tail or common mare's-tail, is a common aquatic plant of Eurasia and North America ranging from Greenland to the Tibetan Plateau to Arizona. It prefers non-acidic waters.Holland Haven Marshes
Holland Haven Marshes is a 208.8 hectare biological Site of Special Scientific Interest north-east of Clacton-on-Sea in Essex. It is an L shaped site which stretches along the coast from Frinton-on-Sea to Holland-on-Sea, and then north along the Holland Brook. It includes Holland Haven Country Park, a 22.1 hectare Local Nature Reserve owned and managed by Tendring District Council.A network of ditches radiates from Holland Brook, and these have several nationally scarce aquatic plant species, such as brackish water crowfoot and divided sedge. The site also has grasslands which are botanically important. There are also rare invertebrates, including the Red Book soldier fly Stratiomys singularior. There are many breeding and wintering birds. The country park has a bird hide, parking and toilets.There is access to the country park from a coastal footpath, but much of the site is on private land with no public access.Hottonia palustris
Hottonia palustris, also water violet or featherfoil, is an aquatic plant in the family Primulaceae.Hydrocharitaceae
Hydrocharitaceae is a flowering plant family including 16 known genera with a total of ca 135 known species (Christenhusz & Byng 2016 ), that including a number of species of aquatic plant, for instance the tape-grasses, the well known Canadian waterweed and frogbit Hydrocharis morsus-ranae.
The family includes both fresh water and marine aquatics. They are found throughout the world in a wide variety of habitats, but are primarily tropical.Koyna River
The Koyna River is a tributary of the Krishna River which originates in Mahableshwar, Satara district, western Maharashtra, India. It rises near Mahableshwar, a famous hill station in the Western Ghats. Unlike most of the other rivers in Maharashtra which flow East-West direction, the Koyna river flows in North-South direction. The Koyna River is famous for the Koyna Dam and the Koyna Hydroelectric Project. Today the Koyna Hydroelectric Project is the largest completed hydroelectric project in India. The reservoir – Shivasagar Lake, is a huge lake of 50 km in length.
Due to its electricity generating potential through Koyna Hydroelectric Project, Koyna river is known as the Life Line of Maharashtra
The river meets the Krishna River, which is one of the three largest rivers in southern India by Karad at Pritisangam
The river is just about 100 meters in width and is slow-flowing. It is an olive shade of green during the dry months and a bluish-brown in the monsoon months attributed to much algae and aquatic plant life.The impounded water of the Koyna Dam though has submerged a significant amount of Rain forest of the Western Ghats, it has helped a lot to the surrounding forest by supplying water all round the year. Hence a wide biodiversity of plants and animals is observed in the evergreen forest surrounding the river.Myriophyllum spicatum
Myriophyllum spicatum (Eurasian watermilfoil or spiked water-milfoil) is native to Europe, Asia, and north Africa, but has a wide geographic and climatic distribution among some 57 countries, extending from northern Canada to South Africa. It is a submerged aquatic plant, grows in still or slow-moving water, and is considered to be a highly invasive species.North Moor
North Moor (grid reference ST325305) is a 676.3 hectare biological Site of Special Scientific Interest near Lyng in Somerset, notified in 1986.
North Moor is a nationally important grazing marsh and ditch system on the Somerset Levels and Moors. A range of neutral grassland types supporting common and scarce plants has developed mainly due to variations in soils and management practices. Aquatic plant communities are exceptionally diverse with good populations of nationally scarce species. The site has special interest in its bird life.North Moor was flooded during the Winter flooding of 2013–14 on the Somerset Levels.Nuphar lutea
Nuphar lutea, the yellow water-lily, or brandy-bottle, is an aquatic plant of the family Nymphaeaceae, native to temperate regions of Europe, northwest Africa, and western Asia.Padma (attribute)
Padma (Nelumbo nucifera, the sacred lotus) is an aquatic plant that plays a central role in Indian religions such as Hinduism, Buddhism, Sikhism, and Jainism. The lotus flower has many different names such as the "Indian Lotus", the "Sacred Lotus", and the "Bean of India".Pistia
Pistia is a genus of aquatic plant in the arum family, Araceae. The single species it comprises, Pistia stratiotes, is often called water cabbage, water lettuce, Nile cabbage, or shellflower. Its native distribution is uncertain, but probably pantropical; it was first discovered from the Nile near Lake Victoria in Africa. It is now present, either naturally or through human introduction, in nearly all tropical and subtropical fresh waterways and considered an invasive species as well as a mosquito breeding habitat. The genus name is derived from the Greek word πιστός (pistos), meaning "water," and refers to the aquatic nature of the plants.Ranunculetum fluitantis
Ranunculetum fluitantis is one of the 24 Aquatic plant communities (A18) included in the British National Vegetation Classification (NVC).
The vegetation type or community comprises stands of submerged vegetation dominated by clumps of River water crowfoot. Few other plants are found with any frequency among the denser stands but there can be Myriophyllum; Potamogeton perfoliatus and patches of moss on submerged stones.Rheophyte
A rheophyte is an aquatic plant that lives in fast moving water currents in an environment where few other organisms can survive. Rheophytes tend to be found in currents that move at rates of 1 to 2 meters per second and that are up to 3 to 6 feet deep. The amount of force produced by these currents, and the damaging debris they can carry, makes this environment inhospitable to most plants. Rheophytes are able to live in such environments because their leaves are streamlined so as put up little resistance to the flow of water. The leaves tend to be quite narrow and flexible as well. In order to prevent the plants from being uprooted, Rheophytes have an extremely strong wide spreading root systems.
Many Rheophytes live in areas that sustain flash floods and they are dependent on the oxygenated water and buoyancy brought along with it. Simply being an aquatic plant with narrow leaves is not a sufficient condition for being a Rheophyte. Also, plants that grow in slow moving water that occasionally receive fast currents aren't Rheophytes either if they don't need these fast currents to survive. Plants that fall into this category are known as facultative rheophytes. When low water levels occur Rheophytes often quickly begin to flower to take advantage of these occurrences.Stanford End Mill and River Loddon
Stanford End Mill and River Loddon is an area of natural grassland, between Beech Hill and Swallowfield in Berkshire, incorporating a stretch of the River Loddon and a mill built in early Victorian times on the Stratfield Saye estate. It was designated a Site of Special Scientific Interest (SSSI) in 1952, and expanded in 1986. The site is of interest mainly because of two rare plants: the fritillary (Fritillary meleagris), a native bulb, and the Loddon pondweed (Potamogeton nodosus), a rare aquatic plant. The area supports a wide range of native meadow plants, and the river supports a variety of coarse fish species, water voles and nesting birds, including little grebe, moorhen, coot, mute swan and kingfisher.Tobico Marsh
Tobico Marsh, located just north of Bay City, Michigan, is part of the Bay City Recreation Area. Tobico Marsh was designated as a registered National Natural Landmark in 1976 because of its large size, relatively undisturbed condition and variety of aquatic plant life. With nearly 2,000 acres (8.1 km2) of wetland woods, wet meadows, cattail marshlands and oak savannah prairies, Tobico Marsh is one of the largest remaining freshwater, coastal wetlands on the Great Lakes.West Moor SSSI
West Moor (grid reference ST420220) is a 213.0 hectare (526.3 acre) biological Site of Special Scientific Interest on the River Parrett in Somerset, notified in 1985.
West Moor lies south of Curry Rivel, Langport, and Drayton, and northwest of Kingsbury Episcopi and is part of the extensive grazing marsh grasslands and ditch systems of the Somerset Levels and moors. The site contains some of the most diverse aquatic plant communities in the country. Rhynes often have a rich aquatic flora Frogbit (Hydrocharis morsus-ranae). A rich invertebrate fauna, with many nationally and locally rare species is associated with the botanical diversity of the ditches.