Algae vs Plants: Difference and Comparison

Some algae, like Euglenoids, are unicellular, while others, like Oedogonium, are multicellular organisms. Alternatively, there are no unicellular plants.

This seminal difference is implicated in several other notable divergences between the two.

Key Takeaways

1. Algae are simple, non-flowering aquatic organisms that can be unicellular or multicellular, while plants are multicellular, photosynthetic organisms with roots, stems, and leaves.
2. Algae do not have specialized tissues or organs like plants, while plants have specialized structures for transporting water and nutrients.
3. Algae are found in various habitats, while plants are mostly terrestrial.

Algae vs Plants

The difference between algae and plants is that while algae can be unicellular or multicellular organisms, plants are always multicellular. Algae may be found as organisms with only one cell or multicellular beings living in colonies.

Hence, sometimes they must be examined under the microscope to be visible to the human eye. Plants have several diverse body parts like roots, shoots, flowers, etc. and thus cannot be unicellular.

Comparison Table

Parameters of Comparison	Algae	Plants
Cellular Composition	Algae can be unicellular or multicellular organisms.	Plants are always multicellular organisms.
Categorization	Algae are classed under the ‘Kingdom Protista’.	Plants are classed under the ‘Kingdom Plantae’.
Vascular Structure	Algae do not have complex vascular systems.	Plants have very complicated vascular structures, including the xylem and phloem systems.
Degree of Mobility	Algae have a higher degree of mobility.	Plants have lower mobility as they are tethered to the ground.
Body Structure	Algae bodies do not have any differentiation between the root-shoot systems.	A potent differentiation between the root and shoot system exists.
Absorption	Do not absorb nutrients from the soil to thrive and survive.	Plants absorb nutrients and water from the soil with the help of their roots.
Chemical Composition	Algae consist of chlorophyll, carotenoid, and phycobilin.	Plants only have chlorophyll and carotenoid.
Commonly Area of Occurrence	Aquatic organisms are found underwater.	Terrestrial organisms that are found mostly on land.
Reproductive Systems	Sporadic reproductive system.	Complex reproductive system.

What are Algae?

Algae are one of the simplest forms of life visible on the earth. As either single cellular or multicellular autotrophic organisms, algae use sunlight and chlorophyll to produce their food.

Their bodies are devoid of any structural differentiations as well as vascular bundles.

Although earlier they were classed as a sub-category of the plant kingdom, Algae now belong to the Protista Kingdom. Usually, algae colonies can be found underwater.

Some forms of algae also tend to grow in snow and on the fur coats of certain animals, like the sloth. Current research suggests that there are about 320,500 diverse species of algae around the world.

Some Algae have a high degree of mobility. Algae colonies found underwater may freely float in the water. Some may have flagellums to help enhance their mobility.

What are Plants?

Plants are multicellular autotrophic organisms that use air, sunlight, and water to produce food, oxygen, and energy. They belong to the Kingdom Plantae and include several sub-categorizations within their broader classification.  

Most plants are highly vascular organisms. They have complex root and shoot systems consisting of connective tissues that help transport food and water through the body.

These xylem and phloem bundles are essential for the transportation of minerals as well as water.

The body of a plant has several parts like the shoot, branches, leaves, roots, etc. Each part has a specific function to perform. Most plants are on the earth’s surface, tethered to the soil.

Although, one can also find aquatic plants growing on the seafloor. However, in both cases, the mobility of a plant is extremely limited.

Main Differences Between Algae and Plants

1. The main difference between algae and plants is that they are different in their cell compositions. Algae can be found as unicellular or multicellular organisms, while plants cannot be unicellular. They are always multicellular organisms.
2. The second important difference between the two organisms is that plants have vascular anatomies, unlike algae. Vascular structures like veins, connective tissues, the xylem and phloem systems, etc., are important parts of a plant’s body. Such complex vascularization is absent from the anatomy of algae.
3. Plants and algae belong to different biological categorizations. Plants are classified under the ‘Kingdom Plantae’, while algae are categorized under the ‘Kingdom Protista’.
4. The degree of mobility available to each organism is also different. While plants are generally tethered to the ground and are, therefore, immobile, algae are free-floating. They have a higher degree of mobility.
5. The differentiation between the root and shoot system commonly found in plants is not in algae.
6. Plants thrive by the absorption of water and mineral nutrients from the soil. Algae do not absorb such nutrients from any surface they may be attached to.  
7. The two organisms also differ in terms of their chemical compositions. While plants have chlorophyll and carotenoid pigments, algae have these pigments along with the phycobilin pigment.
8. Algae are mostly found underwater or floating on the surface of water bodies. Although they are mostly aquatic, sometimes they can be found on land and snow. At the same time, plants are terrestrial organisms found tethered to the topsoil. Sometimes they can be found underwater as well.
9. The reproductive systems of plants and algae are also different from each other. Plants have a complex reproductive system, while algae use sporadic reproduction to propagate their species. They can also self-replicate.

References

1. https://www.nature.com/articles/s41477-018-0211-0
2. https://www.nature.com/articles/nrm3064