Aquatic Plants: Plants That Grow in Water

Since the beginning of creation, many plants have evolved to adapt to the environment. Aquatic plants are a perfect example of evolution. Aquatic plants are special kinds of plants that grow in water. These plants can be Free Floating, Emergents, or Submerged.

Aquatic Plants often form distinct aquatic communities. Some plants are strictly seasonal; they start growing at the beginning of the monsoon. Many are important to the life of the inhabitants of the area. In fact, they are a rich source of nutrients and energy and are considered to be the most efficient converters of solar energy.  Plants that grow in water play a vital role in our planet, the Earth, where 70 percent is water.

What are Aquatic Plants?

Aquatic Plants, also known as hydrophytes or macrophytes, are the plants that have evolved to live in aquatic environments. These plants can be found in seas, rivers, lakes, or ponds. 

A big amount of aquatic plants are members of a heterogeneous group that is composed of a few Bryophytes and Pteridophytes and many of the families of Spermatophytes. In general, aquatic plants can be grouped into 3  categories.

1. Emergent :

Emergent aquatic plants are rooted at the bottom and project out of the water for part of their length. These plants grow in shallow areas. They also grow by the banks of marshes, ponds, lakes, and rivers. Unlike submerged aquatic plants, emergent plants are rooted in the ground with their stems; but, flowers and leaves rising above the water. Emergent plants mainly depend on aerial reproduction and get their nutrients mostly from the soil.

There are lots of species and varieties of emergent plants. These plants can add extra beauty to the ponds or lakes. Although they are really beneficial ( supply cover, nesting areas, and food for different fish and wildlife), they are considered a nuisance.

eg, common species of bulrush, Scirpus.

2. Submerged:

Submerged aquatic plants are those which are continuously submerged. These plants grow under the water. Additionally, they have a root system in the bottom sediment. They have rooted plants with flaccid or limp stems. In fact, most of their mass is below the water surface. But, small portions may stick above the water. They need water for structural support. Plant species in a balanced amount can create a beautiful pond shape and ecosystem.

e.g. Vallisneria.

3. Floating:

Floating plants totally or partially float on the surface of the water and we don’t see them above water. They may have roots that hang in the water, but the plant is not attached to the pond bottom. These plants can be Trailing Floating, Submersed Floating-leaved, or Free Floating. 

eg. Duckweed Lemna

Morphological classification :

Pleuston:

Pleuston is vascular plants that float freely in the water. Pistia stratiotes, an example of a pleuston. These plants are so beautiful and they can float freely on the water surface

Nymphaeids:

Nymphaeids are aquatic plants having mainly floating leaves and flowers. Above or floating on the water surface and are rooted in the soil. These plants are rooted in the bottom, but with leaves floating on the water surface. 

Helophytes:

Helophytes are plants that grow in a marsh. They are partly submerged in water so that it regrows from buds below the water surface. Many fringing stands of tall plants by water basins and rivers may include helophytes.

Isoetids:

Isoetids relies heavily on an abundance of water in order to survive. Many species of isoetids live submerged in lakes or slow-moving rivers. Some rosette plants complete their entire lifecycle submerged in water. 

Elodeids :

Elodeids are aquatic plants that complete their entire life cycle underwater, or with their flowers above. the waterline elodeid species able to compensate for turbid conditions.

Amphiphytes :

Amphiphytes plants are those which are adapted to live either submerged or on land.

Adaptations :

Plants live just about everywhere on Earth. As they live in a variety of different habitats, they evolved adaptations that allow them to survive and reproduce. Maximum plants are adapted to live on land. But some plants now live in the water. They also had to evolve new adaptations for their habitat.

Aquatic plants are plants that grow in water. In fact, Living in water has certain advantages for the plants. One advantage is the water. Most aquatic plants do not need adaptations for absorbing or transporting water. So far, they can save energy and matter by not growing extensive root systems. Also, not having vascular tissues, or thick cuticles on leaves provides them some extra advantage. Support is also less of a problem because of the current of water. Adaptations like strong woody stems and deep anchoring roots are not necessary for aquatic plants. Living in water is a challenge to plants, however. pollination by wind or animals is merely possible underwater, so aquatic plants may have adaptations to keep their flowers above water. For example, water lilies have bowl-shaped flowers and flat leaves and they float. This allows these flowers to collect the maximum possible amount of sunlight, which does not reach very deeply below the water’s surface. Plants that live in streams and rivers, may have different adaptations. For example, cattails have narrow leaves that reduce their resistance to the current. 

Importance of Aquatic Plants:

Food:

Humans have utilized aquatic plants as a food source. Cattails have edible roots and also its pollen has been used in making biscuits. Watercress (Rorippanasturtium aquaticum) has many medicinal uses. And, it is also used in salads and garnishes. Water lilies are a common source of food in many regions of the world and have medicinal value. Even coontail (Ceratophylum demersum) has been used for many medicinal purposes. 

 Plants that grow in water provide important food for many animals. Ducks and many birds eat the seeds, leafy parts, and tubers of plants. Songbirds collect nest material and eat the seeds of many emergent plants. Otter, beaver, muskrats, turtles, and moose will also live on a variety of aquatic plants.

Habitat:

Aquatic plants provide important living space for small animals ( eg. aquatic insects, snails, and crustaceans) which in turn supply food for fish.

Some emergent plants provide nest-building materials for many birds and mammals. In fact, humans make beautiful baskets, mats, boats, and even dwellings from cattail, rush, and bulrush stems.

Cover:

Young fish and amphibians use aquatic plants as a source of cover from predators ( eg. fish and birds). And, with the abundant food supply, makes aquatic plants very important for baby fish, frogs, and salamanders

Nutrient Cycling:

Plants that grow in water are a vital part of the chemical cycling in a waterbody. They influence the supply of oxygen in the water. They utilize nutrients. These nutrients otherwise are used by algae improving water clarity. They can be possibly used as indicators of water quality.

Erosion Control:

Many plants that grow in water( eg. submersed and emergent plants) protect shorelines from erosion from wave action or currents. They can also help stabilize the sediment. It can increase water clarity.For example, wetland plants on the shoreline are a method for stabilizing banks. The deep and robust root systems of these plants bind soils in the area where most of the erosion is occurring. There are many advantages to planting on the shoreline. Because, they can filter pollutants in runoff, by absorbing nutrients that create algae, and trapping sediment and yard debris.

Natural Purifier:

  Plants that grow in water have received a lot of attention for their ability to soak up pollutants from water. They can play a vital role in maintaining a healthy water garden or pond. They absorb carbon dioxide and release oxygen into the water. Also, they improve the environment for fish but absorb nutrients. This reduction in nutrients results in clearer water. Use a variety of plants, including flowering and grass-type plants along the edges, a few floating plants, and two or three dozen bunches of submerged plants. For example, water lilies (Nymphaea spp.) and water poppies (Hydrocleys nymphoides) help to purify the water by absorbing nutrients.

Oxygen Supply: 

About 70 percent of the earth is blessed with restless ocean and water resources. This huge amount of underwater surface is full of aquatic plants. These plants supply three-fifths of the total oxygen of the earth’s atmosphere. So, the huge amount of aquatic plants living underwater can be referred to as a giant oxygen cylinder for the earth’s atmosphere.

Economic Benefits:

The demand for aquatic plants, primarily marine macro-algae has increased at a significant rate over the past few decades.  Countries contributing the majority of wild-harvested macro-algae include China, Chile, Norway, Japan, and Russia. Macroalgae production as a result of aquaculture is greatest in China followed by Indonesia, the Philippines, Korea, Japan, Malaysia, and Vietnam.

The sharp increase in marine aquatic plant harvests probably is the result of the increasing demand for food, pharmaceutical, and biomass; the increase in freshwater plant harvests is possibly driven by the increased popularity of water gardening ( eg. Aquatic planting). Aquatic plants are vibrant and of many other uses to add beautification to the ponds and fountains. Many of the most popular water garden species are imported mostly from tropical and subtropical regions.

The Caulerpa seaweed is really popular in the aquarium industry. It is also highly valued.  Sales of Caulerpa varieties have likely been banned in a number of countries and thus the global value has decreased. Generally, however, human consumption of macroalgae (nori, aonori, kombu, wakame, etc.) remains the primary use. After human food uses, macro-algae hydrocolloids comprise the next largest segment of the aquatic plant industry. 

Why are Aquatic Plants Seen as a Problem?

If aquatic plants are so wonderful but, sometimes they are perceived as a problem. Most of the time, problems arise when plants are so numerous. In fact, they impede recreational activities such as boating and swimming. When growth becomes very thick, they also harm some fisheries. Many juvenile salmon and trout habitat are also harmed. The causes of unnaturally high levels of plant growth are sometimes very complex. Often the reason is increased nutrients, which come from around the lake or in the watershed. More problems can include failing septic systems fertilizer run-off or agricultural waste. Eventually, these increased nutrients cause the natural process of lake aging. The accelerated rate of increasing plant and algal growth is part of this process. If a nonnative species is inadvertently introduced to the lake, another problem arises. This often happens when someone discards aquarium plants into a lake. Several exotic species such as Eurasian watermilfoil (Myriophyllum spicatum) or Brazilian elodea (Egeria densa) can crowd out more desirable native and proved to be very aggressive. Changes in the ecosystem may take a long time or occur quite rapidly. 

Along with preventing or eliminating pollution, you can monitor plant community changes by collecting and identifying aquatic plants on a year-to-year basis. This is also a good way to detect detrimental changes at an early stage when control or elimination of the problem is both less complicated and less costly. Collecting and preserving plants is not difficult, and the result is an increased awareness of aquatic plants, as well as a valuable historic record of what grows in the lake. However, proper identification of the plant can be tricky and is essential, particularly if you believe any to be exotic invasive species.

Conclusion:

The true benefits of plants that grow in water to people are really far-reaching with many new uses yet to be discovered. So far, aquatic plants are being used for multiple purposes. They are really important to maintain a balanced ecosystem. Although, currently, both marine and freshwater habitats are being threatened by the introduction of aquatic plant species. These species become problematic under certain conditions. Species like these should be controlled. In fact, these plant species are often introduced from other parts of the world for beneficial uses, and then escape cultivation to form natural populations. Thus, aquatic plants fulfill a wide range of ecological roles. They make a substantial contribution to the structure and function. They are truly important for the service provision of aquatic ecosystems.

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