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Classification is the process of classifying organisms according to their similarities or differences. It allows for a systematic analysis of many organisms. In 1969, R.H. Whittaker developed the five-kingdom classification. The five-kingdom system relies on specific characteristics, such as nutrition mode and thallus organization. It also considers reproduction. This classification divides the organisms’ word into the following five kingdoms- Plantae, Monera, Animalia, Protista and Fungi.

Kingdom Plantae: These are the most important characteristics or features of Kingdom Plantae.

  1. Plantae covers all eukaryotes with chloroplasts.
  2. They are not mobile.
  3. They are self-sustaining but can be heterotrophic.
  4. Cell walls are mostly made of cellulose.
  5. They can reproduce sexually or vegetative propagation asexually.
  6. The life cycle for plants can be split into two distinct phases that are interrelated. These phases are the  haploid (gametophyte) and diploid (sporophyte) stages.
  7. Different plant groups might have different lengths for the haploid and diploid phases. This phenomenon is known as the Alternation of Generation.

Classification of the Kingdom Plantae or Classification of Plants:

  • These are the basic principles of the Kingdom Plantae classification:
  • Plant body: This is about the well-differentiated plant body. Its presence or absence is considered in the classification of Plantae. Examples include stems, roots and leaves.
  • Vascular system: This system transports different substances like water and minerals from one place to the next. It is also important to consider its presence or absence in the classification of the kingdom- Plantae.
  • Seed formation: The basis for a plant’s classification is the presence or absence of a flower or seed in it.
  • These characteristics are what allow the kingdom Plantae to be divided into five different categories: The plant kingdom classification is given below:
  • Thallophyta:
  • Thallophytes have a poorly differentiated body structure. They have a thallus-like plant body.
  • Thallophyta plants have simple and primitive body structures. Their body is known as thallus.
  • They can be filamentous, colonial, or branched.
  • These three types of algae are excellent examples of this category: red algae, green algae, and brown algae.
  • Examples include Volvox and Spirogyra as well as Chara, Ulothrix and Polysiphonia.
  • Bryophyta
  • They do not have vascular tissues in them.
  • The plant body is composed of stem, root, and leaf-like structures.
  • Bryophytes, which are terrestrial plants, are known as “amphibians” of the plant kingdom because they need water to reproduce
  • Bryophyta can be located in both moist and shaded places. The classification of bryophytes is further done by dividing this category into Hepaticopsida, Anthocerotopsida, and Bryopsida.Bryophyta consists of mosses and hornworts as well as liverworts.
  • Marchantia and Funaria are some of the most common examples of this category.
  • Pteridophyta:
  • The root, stems, and leaves can be distinguished in Pteridophyta. Therefore, they have a well-differentiated plant body.
  • They possess a vascular system that allows for the conduction of water and other substances.
  • Selaginella and Equisetum are some of the most common examples of this category.
  • Gymnosperms
  • Gymnosperms possess a differentiated plant body; the stem, leaf and roots can be recognized in them.
  •  They also have vascular tissue to transport different substances.
  • The seeds they bear are naked, which means that the seeds are not contained within a fruit.
  • Examples of gymnosperms include Ephedra, Cycas, and Pinus.
  • Angiosperms
  • They also have a well-differentiated body; one can easily recognize the root, stem, and leaf.
  • Angiosperms have a vascular system for the transport of different substances in the body; therefore, they are called vascular plants.
  • They also bear seeds. However, they contain their seeds within the fruit.
  • Angiosperms can be found all over the world.
  •  They have a wide range of sizes from 0.1 cm to 100 meters tall.
  • Angiosperms can be further classified based on the number of cotyledons in the seeds into monocotyledons and dicotyledons.
  • Mango, rose, tomato and onion are some of the most common examples of this category.