Generations ago, people believed that anything green that was not considered an animal was a plant. Today, you know that not all green things are plants and that some plants aren’t green at all. In 1978, a modern classification of plants was proposed by plant ecologist, Robert Whittaker, who gave five divisions: monera (single-celled organism), protoctista (mainly fresh water aquatic plants), fungi (ascomycete, basidiomycete, chytria and penicillium conidiophor), plantae (algae, all seaweed and kelp) and animalia (sponge, jellyfish, insect, etc). The role of aquatic plants is so essential for survival that they belong to two divisions: Plantae and Protoctista.
Function, Physical Characteristics and Adaptation of Aquatic Plants:
Aquatic plants, also termed as hydrophytes or aquatic macrophytes, live within watery environments. In the ecosystem, aquatic plants serve as food and habitat for animals living in the sea and prevent shorelines, ponds and lakes from eroding by providing soil stability.
Characteristics common to aquatic plants:
1. Most aquatic plants do not need cuticles or have thin cuticles as cuticles prevent loss of water.
2. Aquatic plants keep their stomata always open for they do not need to retain water.
3. On each side of their leaves are a number of stomata.
4. Aquatic plants have less rigid structure since water pressure supports them.
5. Since they need to float, leaves on the surface of plants are flat.
6. The presence of air sacs enables them to float.
7. Their roots are smaller so water can spread freely and directly into the leaves.
8. Their roots are light and feathery since they do not need to prop up the plants.
9. Roots are specialized to take in oxygen.
Adaptation of aquatic plants is evident by their structure: deeply dissected and waxy leaves, specialized pollination mechanism and variation in growth pattern. These are the types of plants based on adaptation:
1. Totally submerged plants – Are considered true water plants or hydrophytes. Example: Water starwort submerged in a marsh pond.
2. Floating plants – Are rooted in floating water (example: water lily) or not rooted in the sediment just on the surface (example: duckweed).
3. Swamp plants – Are emergent plants with their lower part submerged. (Example: reed mace).
Scientists of the National Science Foundation (NSF) claimed that there is an overwhelming proof that the ancestors of modern terrestrial plants evolved in aquatic environments. Over a million of years in the area where they used to survive, aquatic plants diversified. One group coming from these organisms, possibly the ancestors of modern species of protoctistas known as green alga, started a new branch of the tree of life. From this branch, emerged four groups of land plants, including the mosses, the ferns, the conifers, and the flowering plants. These four groups represented a series of events which reflected evolutionary history of land plants.
According to Professor Patrick Martone of the department of Biology, University of British Columbia, all land plants evolved from aquatic green algae, and scientists have long believed that lignin evolved after plants took to land as a mechanical adaptation for stabilizing upright growth and transporting water from the root.
Plantae and Protoctista:
1. Plantae (sensu strictissimo, sensu stricto and sensu lato) – It is distinguished from all the other plants because its cells have cell walls made of cellulose whose basic function is to support the plant. Their cell walls do not have semi-permeable membrane and the cell does not carry nutrients within the cell walls. Its large central vacuole conserves water and chemicals that are useful inside the cell. Plantae has chloroplasts that transform light energy into chemical energy which is stored as sugar – this characteristic is only found in this type of plant.
Divisions are: Bryophyta is made up of liverworts and hornworts; Sphenophyta consists of horsetails, which are basically stems; Anthophyta is the largest grouping of flowering plants; Coniferophyta bears its seeds in the form of a cone; Ginkgophyta came from China and when reproducing, the female’s egg produces a very bad smell and Filicophyta which is made up of ferns that live near water, rain forest or ponds. Most members of the division are aquatic plants.
2. Protoctista, also known as protista, is comprised of the eukaryotic microorganisms and their immediate descendants: all nucleated algae (including the sea-weeds), undulipodiated (flagellated) water molds, the slime molds and slime nets, and the protozoa. They are aquatic: some primarily marine, some primarily freshwater, and some in watery tissues of other organisms. They are single-celled organisms and live in watery environment. Examples of protoctista's are slime moulds, algae, cilia, flagella, pseudopodia and others.
Aquatic plants are classified as:
1. A planmergent is one whose conspicuous portion of its vegetative plant body is on the water surface or all of the vegetative plant body is primarily underwater. Examples: eelgrass, widgeongrass, Eurasian watermilfoil, coontail and musk grass.
2. An emergent plant is one which grows in water but which rises up to the surface so that it is partially on air. Examples: reed, flowering rush and wild rice species.
Aquatic plants have different types of habitat: can be wet (riparian), can be in shallow standing water (marsh) and open water (aquatic). Their classification is based on habitat:
1. Free floating – example: duckweed
2. Totally submerged – example: naiad
3. Bottom rooted and floating – example: water lily
4. Emergent and rooted – example: quillwort
5. Totally emergent – example: cattails
6. Streambank and wet areas – example: alders
Some aquatic plants bear flowers and, today, they are becoming more and more popular as many avid gardeners are turning their attention to the area of water gardening. A pond or garden with flowers will give you peace and relief after a day’s work. If you’re intending to create a pond or water garden, you should learn more about aquatic flowers.
You will enjoy the beauty of aquatic flowers as they come in different varieties: based on size, appearance, and the nature of how they grow.
Some common varieties of aquatic flowers are:
1. Water lilies (nymphaea odorata) are classic lily pads associated with ponds and even frogs. Lilies bear blossoms that last for a lengthy period of time and also give shade on the pond. They keep water clean and clear and reduce the amount of growing algae.
2. Pygmy water lilies (nymphaea tetragona) are the smaller version of water lilies and look best on smaller ponds or tub-like gardens. They occupy less space and provide shelter for frogs and fish.
3· Water poppy (hydrocleys nymphoides) are small yellow aquatic flowers with bright green leaves. They grow during late springs and summertime. Their unobtrusive size makes them an ideal partner for lilies.
4. Water hawthorns (apogeton distachys) are white fragrant flowers with a black center and have bright green leaves and they bloom for the rest of the year. It mixes beautifully with lilies in the flower garden or pond.
5· Duckweed (lemna minor) is a floating plant that looks great in any pond with fish living in it. It gives the fish shelter and food.
6· Water lettuce (pistia stratiotes) resembles a head of lettuce but is not suitable in a cold climate.
7. Japanese iris (i. ensata) can grow as tall as three feet and bears purple, white or dark red blossoms in November and December. These flowers need lots of sun to survive.
8. Lizard’s tail (anemenopsis californica) has heart-shaped leaves with pleasant creamy-white flowers in the summertime; it requires lots of sun.
9. Water cress (rorippa nasturtium aquaticum) grows quickly and displays attractive small white flowers. It needs sunlight to stay healthy. Water cress is edible and a popular healthy ingredient used in many leafy salads.
Care of Plants and Flowers:
If you have a green thumb or you just love gardening, one of your best options is to start an aquatic garden. Instead of anchoring on the soil, aquatic plants attached their roots under the water or on moist soil. You will be awed by your flowering aquatic plants for they bear some of the most striking and attractive flowers. Your flowering aquatic plants will be a success if you make the proper selection of blooms.
Choose the right kind of flowers: for instance, water lilies and water iris can withstand overnight frosts while golden button and lobelia need warmer climate. Underwater banana plants and eel grass are fine for they are oxygenating plants which support the lives of fish and snails in your pond. A big pond is ideal for creating the best ecosystem. Different plants need different types of containers. If your container is in a smaller scale, you will need a water filter. Choose deep containers to enable plants to lay their roots.
To enable aquatic plants to lay their roots, place 2 to 3 inches of soil in the bottom of container. Prevent soil from mixing with water by covering the soil with heavy pebbles or gravel. If your pond is large enough, you can even submerge flower pots with the plants. To maintain healthy appearances of your plants, check the pond for presence of invasive non-flowering aquatic plants. If water is too cold, install a heating system or do not start planting until the warmer time of the season. Regularly check the low level of CO2 and conduct pH testing to monitor carbon dioxide level. To avoid spots or holes on the leaves, clear water of dead and rotting materials to control bacterial infection called cryptocoryne disease.
Use of Aquatic Plants to Man
1. Aquatic plants and flowers give joy and pleasure as man beholds its beauty, variations of design, colors and shapes. Maintaining a pond or garden filled with different aquatic varieties and blooms are becoming popular.
2. As you can see aquatic plants not only give scenic beauty to what might otherwise be quite a colorless- looking pond but it also serves as a valuable natural oxygenator. Water lilies and the other features of the pond are using phosphates and nitrates, the end result of the nitrogen cycle. Water cress makes an excellent nitrate removal.
3. The trend of maintaining aquatic garden in many homes opened a new avenue for business and a source of income. There are pioneering entrepreneurs who saw the rich potentials of aquatic plant business.
4. Culinary and herbal uses of aquatic plants – Since the start of history, mankind had been eating edible water plants and using aquatic plants as food source. For example, the seeds, stems and rhizomes of nelumbo are eaten and considered a delicacy in China. The Indians of North America eat the fleshy part of nelumbo lutea which tasted like sweet potatoes. Watercress (Rorippa nasturtium-aquaticum) is being utilized as medicine and its tangy vegetation is used in salad and garnishes. Water lily roots are not only food source but medicinal as well.
5. Use of some aquatic weeds as paper pulp – The Cellulose Research Institute and Topical Pest Biology Program is studying the potential use of water hyacinth, torpedo grass and giant bulrush as paper pulp.
6. Use of aquatic plants in removing heavy metals from wastewater - Terrestrial and aquatic plants possess high metal absorption capacity, and can be used as inexpensive materials for removing metals from wastewater and environment.
Aquarium Plant Species
When most people start creating an aquarium, their main purpose is to watch the fish; however, in time, they will realize how much the natural setting provided by aquatic plants makes an ideal background to showcase the fish. Plants enhance the quality of the water by biological filtration, remove nitrates, and oxygenate the water. Fish living in a well-planted tank are less stressed and more likely to breed.
Here are the some of the best aquarium plant species:
1. Moss (SPHAGNUM MOSS) is a tiny and soft plant. It grows fast and provides a safe breeding place for fish in the aquarium.
2. Java ferns (Microsorum pteropus) It originates from the waters of Java. Being a hardy plant, it adapts to most water conditions including brackish water. It survives even in low light condition and grows stuck to any surface; that’s why it is a favorite aquarium plant. Many fish like to hide or leave their eggs on Java fern.
3. Anubias (Anubias heterophylla) Anubias can grow quite tall and so is best suited as background of the aquarium.
4. Amazon sword (Echinodoras) One of the most commonly available aquatic plants is the Amazon swords. It is a beautiful plant, with deep green leaves; the shade depending on the light going on or through the aquarium and it lives long. It is really a good plant in an aquarium.
5. Water Hyacinth (Eichhornia crassipes) It absorbs fish waste, ammonia and other dirt making the water healthy for the fish. It also absorbs lots of oxygen from water serving as a good aeration system.
6. Water lettuce (Pistia stratiotes) Water lettuce provides good shades for residents in the pond. Some goldfish and koi develop a taste for their roots. Water lettuce offers fish a variety in their diet.
7. Water sprite (Ceratopteris thalictroides) Water sprite, known as the Indian Fern, is a mid-ground and floating plant. Its delicate and lacy leaves are ideal camouflage for fry to conceal themselves.For newbie aquarists, water sprite makes a great started plant.
8. Elodea (Egeria densa) Elodea is another one of those easy plants to grow and take care of. Just cut the stem and place into the gravel. It looks best in your aquarium.
Your aquarium would look as pretty as you want it to be. So take your time in choosing only the right kind of aquatic plants. For more information, refer to the links below: