Some Other Criteria of Classification of Plants: Everyone knows what a plant is. It is the organism that can prepare its own food. Without plants, life is impossible for us. All green plants have the same function but do you know they are categorised differently on different bases? Like plants are categorised into herbs, shrubs, and trees according to their shapes and sizes. In the same way, there are other bases too of classifying plants. What are those? Here in this article, we have discussed some other criteria of classification of plants: life span, mode of nutrition, habitat. To know these classifications, let’s read the full article.

What is Classification, and Why is it Needed?

Classification refers to the grouping of living things together according to their features or functions in common. It is needed:-
a. To find out desired organisms of known characters from a vast array of living organisms.
b. To understand the different organisms properly with respect to their features, similarities, and differences with other organisms.
c. It also helps in understanding why that particular organism is grouped under a particular category.

Classification of Plants on the Basis of Life Span

On the basis of life span, plants are classified into three categories:-

1. Annuals– It refers to the plants that are able to complete their life cycle in one year. They germinate, produce fruits and flowers, and die all in one year.
   Examples: Mustard, sunflower, pea, rice, etc.

Fig: Sunflower

2. Biennials – It refers to the plants that complete their life cycle in two years. First, growth of leaves occurs and then stem elongation followed by flowering, seed formation and death. These all processes take two years, so these are called biennial plants.
Examples: Onion, potato, carrots, etc.

Fig: Onion

3. Perennials– It refers to the plants that live or complete their life cycle for three or more than three years. These types of plants do not die off altogether. But once they grow, its root system remains intact and other parts like fruits, flowers, and leaves come and go season after season from the same root system. They can be evergreen like that of a rose plant.
Examples: Rose plant, mango tree, banyan tree, pine tree, etc.

Fig: Mango

Classification of Plants on the Basis of Mode of Nutrition

On the basis of mode of nutrition, plants are classified into

1. Autotrophs- This refers to the plants which can prepare their own food by the process of photosynthesis, with the help of sunlight.
   Example: All green plants.

Fig: Photosynthesis

2. Heterotrophs- It refers to the plants which cannot prepare their own food, but depend on others for their nutrition. These are again of following types:-
(a) Parasitic plants- In this type of nutrition, plants obtain their nutrition from other plants, and in turn, the host plant from which the parasitic plant is taking nutrition gets harmed and not benefitted.
Example: Cuscuta. This plant lacks chlorophyll so it cannot prepare its own food.

Fig: Cuscuta

(b) Saprotrophic plants- These plants obtain nutrition from dead and decaying matter.
Examples: Mushroom, bread moulds.

Fig: Mushroom

(c) Insectivorous plants- These plants have chlorophyll and can prepare their own food through photosynthesis. But due to the lack of some minerals like nitrogen in the soil, they need to depend on insects. For that, they trap insects, ingest and digest them by secreting digestive juices on them.
Examples: Pitcher plant, venus fly trap, etc.

Fig: Pitcher plant with insect

Fig: Pitcher plant

(d) Symbiotic plants- In this relationship, two types of plants are in close association with each other, and both the plants get benefitted from each other. This is a symbiotic relationship like in the case of Lichen, where algae and fungi are in close association with each other.
Example: Lichen

Fig: Lichen

Classification of Plants on the Basis of Habitat

On the basis of habitat, plants can be divided into the following groups:-

1. Hydrophytes- Plants that grow in water are called hydrophytes. Hydrophytes can be totally submerged or floating plants. Their roots are absent or poorly developed. Leaves may be floating coated with wax-like substances.
   Example: Lotus.

Fig: Lotus

2. Xerophytes- These include plants that grow in deserts. Their roots are long, penetrate deep into the soil. The leaves are modified into spines, stems are thick and spongy, which stores water.
Example: Cactus.

Fig: Cactus

3. Mesophytes- These include plants that grow at optimal temperature and require sufficient amounts of water and soil. It has properly developed roots with root hairs, shoots with stems and leaves.
Example: Mango tree.

3. Halophytes- These are salt-loving plants and grow in saline environments. They have succulent leaves to retain some water, and their bodies have thick cuticles to prevent water loss. It has a special type of roots called pneumatophores, which is negatively geotropic and have small pores to exchange gases.
Examples: Mangrove trees.

Fig: Mangroves

Summary

From the above discussion, we came to know about different types of plants based on their life span, mode of nutrition, and habitat. Based on their life span, plants are divided into annual, biennial, and perennial plants. Annual plant completes its life cycle in one year, biennial in two, and perennial plant in more than two years. On the basis of mode of nutrition, plants are of two types, autotrophic and heterotrophic. Autotrophic means they can prepare their own food, while heterotrophic refers to the plants which cannot prepare their own food but depend on others. On the basis of their habitat, plants can be xerophyte, mesophyte, hydrophyte, and halophytes. Xerophytes are found in deserts, hydrophytes in an aquatic medium, halophytes in saline medium, while mesophytes are found in the average environment with their developed roots in the soil. These plants require adequate water, optimum temperature, and moisture to grow.

FAQs on Some Other Criteria of Classification of Plants

Q.1. How are plants classified based on their habitat?
Ans: On the basis of habitat, plants can be classified as hydrophytes, mesophytes, xerophytes and halophytes.

Q.2. How are plants classified on the basis of their life span?
Ans: On the basis of life span, plants are classified as annual, biennial, and perennial plants.

Q.3. How can we classify plants based on their mode of nutrition?
Ans: On the basis of mode of nutrition, plants are classified as autotrophic and heterotrophic plants. Heterotrophic plants are further classified as saprotrophic, parasitic, insectivorous, and symbiotic plants.

Q.4. What are heterotrophic plants?
Ans: Heterotrophic plants are those plants that cannot prepare their own food but depend on others. Pitcher plants are insectivorous plants. Although they can prepare their own food by the process of photosynthesis as they have chlorophyll, due to nitrogen deficiency in the soil, they depend on insects to compensate for nitrogen deficiency.

Q.5. What are xerophytic plants?
Ans: Xerophytic plants are plants that are found in deserts. E.g., Cactus. They have different adaptations to grow in less water.

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