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Why do Plants Float? The Facts Explained

Have you ever wondered why plants float? Well, the reason why they float may seem relatively simple, and here’s why.

Plants float because of the presents of air spaces between the plant cells. Air is more buoyant than the surrounding water, predominantly causing the biological mass of cells containing the air to float on the water’s surface rather than sink. Aquatic plants are well adapted to floating on water for their entire life cycle.

Plants that float on the water’s surface can have small, oval-shaped floating leaves, like a water lily. Duckweeds and Azolla are shaped like corks and can float for very long distances.

Floating plants are also known as waterweed, water hyacinth, etc. 

Many aquatic plants have evolved to float in order to survive harsh conditions and get to more suitable spots for growth. This article teaches more about why plants float and a list of all floating plants. 

Why Do Plants Float?

why do plants float

Some plants retain unique adaptations which enable them to stay on the water surface. They have particular air-filled tissues and cells in their shoots (freshly grown parts above the ground like leaves, stems, flowers, etc.) known as aerenchyma cells

The air in these cells refers to gasses like oxygen and carbon dioxide. 

The aerenchyma cells create free spaces in the roots and shoots of plants and allow the exchange of gasses between them. 

The gasses in aerenchyma make the aquatic plants less dense than the other plants. Thus, helping them to float on the chest of water. 

Do all Plants Float on Water?

No, all the plants do not float on water. Terrestrial plants (plants that grow on land) can’t survive and float on the water. But some aquatic plants tend to develop and float on the water surface.

Aquatic plants that grow in or on the water surface are also known as hydrophytes or macrophytes.

What are Floating Plants Called?  

Floating plants are named depending upon their diversity and different categories. Floating plants can be categorized into three groups.

Free-FloatingPartially EmergedCreepy Floating
These plants move freely on the water chest.These plants just have their leaves and flowers floating on the water.These plants form creepy extensions, Covering the water surface uniformly.
They don’t have a root system.Their roots are attached to the substrate at the bottom of the water.They grow near the shores, and their roots are anchored to the coast.
E.g., water hyacinth and mosquito fern.E.g., water lilies, and lotus.E.g., water primrose and alligator weed.

How are Underwater Plants Different From Floating Plants?

Underwater plants differ from floating plants in all aspects. I would highlight the difference between them through a comparison.

Floating PlantsUnderwater Plants
Floating plants have their stomata on the upper side of the leaves for gaseous exchange.Underwater plants do not have stomata because they absorb dissolved gasses within the water.
Their stomata are permanently open.Stomata is absent.
The upper part of floating leaves has a waxy cuticle to inhibit water loss.Underwater plants do not have cuticles on their leaf surface. 
Floating plants are lighter than water due to the free spaces between cells.Underwater plants are denser than water.

Do Floating Plants Prevent Evaporation?

Yes, floating plants can play a vital role in preventing evaporation. 

If you want to preserve water in a pond or lake from evaporating, you may cover the water surface with numerous floating plants. 

Floating plants will cover the water surface in such a way as to reduce exposure to sunlight. As a result, the sun’s scorching heat will not impact the water to evaporate. This is why the water channels containing such plants don’t vaporize quickly.

Do Floating Plants Provide Oxygen?

Floating plants possess stomata on the upper layer of leaves. These stomata are exposed to the external environment and allow a convenient gaseous exchange. By doing so, they will undergo the photosynthesis process.

As they tend to perform photosynthesis, they would surely inhale carbon dioxide and produce oxygen. 

Do Floating Plants Have Roots?

The presence of roots in the floating plants varies concerning their categories.

Although all the floating plants have roots, some have their roots nipped in the bottom of the water while others have them floating freely.

Some floating plants have extensive roots to absorb the maximum nutrients from the water. Floating roots are spongy and have spaces to accommodate air in it. These air-filled roots give the plants the ability to swim.

Can Floating Plants Be Planted on The Ground?

No, floating plants cannot be grown on the ground. It is insane to grow aquatic plants in a terrestrial environment.  

Aquatic plants consume and require considerable water to grow. Growing them on the land would be unfair as the water provision will not be enough to quench their thirst.

Moreover, floating plants acquire a unique body design, and they cannot match the environment other than water. Even their roots cannot absorb water and nutrients from the deep soil.

How Do Floating Plants Get Nutrients?

Floating plants get all the essential nutrients from the water and the surrounding environment.

Here I would elaborate on how aquatic plants acquire significant nutrients. 

Sunlight

All types of floating plants have pretty easy access to sunlight.

Freely floating plants are visibly exposed to the sunlight and continuously receive its rays. 

The submerged and partially floating plants are concerned; they also receive the required sunlight because the sun rays penetrate through the water and reach these plants.

Nitrogen

All the floating plants retain the required nitrogen from the water where they grow. This nitrogen primarily comes from the living bodies and other wastes dissolved in the water.

Floating plants absorb this nitrogen through their roots and shoots and ingest it as food.

Carbon Dioxide

Free-floating plants have their leaves exposed to the external environment. Thus, they inhale carbon dioxide from the surrounding through stomata present on the upper side of their leaves.

While partially emerged and submerged plants obtain carbon dioxide through photosynthesis. 

When these plants breathe, water vapors escape through the stomata, and the dissolved carbon dioxide diffuses into it. 

Other Minerals

Plants also require minerals like potassium, magnesium, iron, and manganese to grow appropriately. 

Ocean water is enriched with these minerals, so the plants growing there won’t face their shortage. 

If we grow the floating plants in an aquarium or a tank, we will manually add these minerals to ensure healthy growth.

List of Floating Plants:

There is an endless list of floating plants. But I would enlist some of them; 

  1. American Featherfoil
  2. Dotted Duckweed
  3. Common Salvinia
  4. Water Lilies
  5. Bladderwort
  6. Floating Crystalwort
  7. Giant Salvinia
  8. Rooted Water Hyacinth
  9. Florida Mud Midget
  10. Watermeal
  11. Giant Duckweed
  12. Water Lettuce 
  13. Water Hyacinth
  14. Duckweed 
  15. Mosquito fern (Azola)

And the list goes on.

Floating Plants For Your Aquarium:

Growing floating plants in an aquarium is an efficient way of making it the perfect habitat for fish. Floating plants can boost the healthy production of fish in many ways.

Keeping these plants in the aquarium inhibits excess evaporation and regulates the aquarium’s temperature. Floating plants absorb carbon dioxide from the water, leaving behind a cooling effect.

Floating plants filter the water by absorbing minerals like potassium and magnesium, fatal for fish. They can also feed algae as a nutrient, which can be harmful to fish by consuming oxygen.

5 Best Floating Plants for an Aquarium:

1. Java Moss

It is one of the unique and suitable floating plants for an aquarium. This plant can spellbind the viewer with its fascinating and attractive appearance. It is an environment-friendly floating plant and can do wonders in every atmosphere.

Java moss does not have roots, and it floats freely in the water. It sticks or gets rolled around the rocks or anything it finds due to its migratory movement.

Therefore, it should be connected to any cork or an object to overcome its clinging habit.

2. Duckweed

Duckweed is another aquatic plant that can flourish in every environment. Its captivating beauty and the ability to grow fast are the reasons behind its fame. It can give an aesthetic look to your aquarium.

Duckweeds are tiny, freely floating plants with limited root growth. These plants thrive and tend to cover the whole water surface within days. Therefore, one should trim them on alternate days to maintain and limit their growth.

I would not recommend you grow them if the creature in your aquarium requires               relatively more light

3. Water Lettuce

Water lettuce is widely praised and loved among fishkeepers and aquarium owners. It is a unique and attractive plant that adds beauty and charm to the fish tank. It provides a completely natural look to your aquarium.

Water lettuce has large-sized glowing green leaves; baby fish and shrimps might use them to play hide and seek. It can also help to filter water by preventing algae growth.

Due to their large leaves, the fishkeepers must ensure that the appropriate light reaches the creature.  

4. Water Spangles

Water spangles are floating plants having comparatively small leaves with brown root-like bottoms. Water spangles show fast growth, and they do not need much care to produce.

Water spangles can survive in almost all aquatic situations, and they don’t require extra nutrients to develop. They can adapt to minor changes in water temperature. They can live and grow in moderate to higher temperatures (16° – 32° C).

Aquarium holders need to maintain the balanced growth of these floating plants to stop them from covering and choking the fish tanks.

5. Azolla

Azolla is another floating plant that one can consider having in an aquarium. It is commonly known as the mosquito fern. The limited and slow growth of the Azolla plant distinguishes it from many others. 

Mosquito ferns have tiny green leaves attached to the stem, slightly up from the water surface. They can be grown in temperate, sunny, and shady areas. Their optimum temperature ranges from  20-30°C. 

You should consider while growing these plants that their leaves and stems are above the water surface. Otherwise, they won’t grow well.

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