Plant Kingdom

The five-kingdom classification groups all living organisms into Monera, Protista, Fungi, Plantae, and Animalia. The kingdom includes multicellular, eukaryotic organisms that photosynthesise and manufacture their own food. Here, the plants are characterised by their structure, reproduction and adaptation. They play a major role in the ecosystem as producers and are found at the base of the food chain.

This Story also Contains

1. Kingdom Plantae Characteristics
2. Reproductive Features of the Plant Kingdom
3. Physiological Features of the Plant Kingdom
4. Classifications of Kingdom Plantae
5. Recommended Video on Plant Kingdom

The classification has ranged from simple observation to modern molecular techniques. Plants are very important because they provide oxygen, along with various other things. They also help in maintaining nature’s balance, fight climate change and prevent species extinction. The Plant Kingdom is important in biology, as it forms the base for advanced studies in botany and ecology.

Important Topics of Chapter Plant Kingdom

• Algae
• Bryophytes
• Pteridophytes
• Gymnosperms
• Angiosperms

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• Animal Kingdom
  
• Coelom
• Notochord

Kingdom Plantae Characteristics

The following are characteristics of the plant kingdom. Kingdom Plantae have several fundamental characteristics that distinguish it from other organisms:

• Multicellularity: Flowers are made up of specialised multicellular cells forming tissues and organs.
• Photosynthetic Autotrophs: They are mostly autotrophic; they prepare their food with the help of the green pigment known as chlorophyll in photosynthesis.
• The Presence of Cell Walls: The plant cells are covered by a cell wall, mainly containing cellulose to provide rigidity and protection to the cell.
• Chlorophyll Types a and b: These also have green coloured chlorophyll a and b to enable the light to be absorbed by the plant.

Reproductive Features of the Plant Kingdom

• Both gymnosperm and angiosperm life cycles are characterised by alternation of generations, involving two distinct multicellular phases: and comprises, the haploid gametophyta and the mainly diploid sporophyte.
• The phase that is prevalent in the life cycle, called the gametophyte, produces gametes through meiosis; a fusion of egg and sperm, and the zygote is formed.
• It differentiates into the sporophyte, and these sporophytes produce the haploid spores through meiosis. Such gametophytes grow into new gametophytes, and as such, the lifecycle of the plant is completed.

Types of Reproduction

• Sexual Reproduction: It refers to the fusion of gametes brought by the gametophytes, and this causes variation in offspring.
• Asexual Reproduction: This happens in a manner that involves fragmentation, budding or formation of reproductive structures like the bulbs and tubers, which form plants without fusion of gametes.

Physiological Features of the Plant Kingdom

Plants perform several important physiological processes that sustain their growth, development, and interaction with the environment:

Photosynthesis

• Chlorophyll is a pigment in chloroplasts in plants that enables light energy to be changed into a chemical form, glucose, which the plant uses for energy, and the byproduct of this process is oxygen.
• Photosynthesis is important for getting energy for the metabolic activities of plants and for the synthesis of oxygen used in aerobic respiration by living beings.

Respiration

• Through cellular respiration, plant cells can split glucose molecules and release free energy for use in other cellular processes. This process, called cellular respiration, takes place in the mitochondria, where oxygen is used in the process and carbon dioxide and water are formed as waste.
• Regulation assists in the growth, development, and reproduction of plants throughout the process of respiration.

Transpiration

• Stomata on the leaves of plants enable the process of releasing water vapour into the surroundings.
• It helps in controlling temperature, water uptake by the plant and absorption of other minerals from the ground.
• Transpiration generates a pressure that drives the movement of water and nutrients from roots to the shoots, promoting plant development and nutrient distribution.

Classifications of Kingdom Plantae

Plants are classified by their structure, reproduction and adaptation. Given below is the classification of the Kingdom Plantae in detail:

Thallophyta

• Thallophytes have a thallus-like body structure and lack a well-differentiated body structure.

• Plants of the Thallophyta family have a primitive and simple body structure.

• The thallus is the plant's main body, and it can be filamentous, colonial, branching, or unbranched.

• Algae such as green algae, red algae, and brown algae are examples. Volvox, Fucus, Spirogyra, Chara, Polysiphonia, Ulothrix, and other species are common examples.

Bryophyta (Mosses)

• They usually have low-growing, attached to the ground in appearance.
• Mosses are bisexual and reproduce through the formation of spores in capsules at the tips of stalks called setae, which are formed from the gametophyte plant.
• Vascular tissues are absent in bryophytes. Root-like, stem-like, and leaf-like components make up the plant's body.
• Bryophytes are terrestrial plants that are also known as "Amphibians of the Plant Kingdom" since they require water for sexual reproduction.
• They survive in wet, shaded environments. Mosses, hornworts, and liverworts are all members of the Bryophyta family.
• Marchantia, Funaria, Sphagnum, Antheoceros, and some examples.

Pteridophyta (Ferns)

• Ferns are among the vascular plants that have true roots, stems (rhizomes), and leaves (fronds).
• They reproduce through spores, and the spore-producing structures or sporangia are found on the surface of fronds, particularly the undersides.
• Most ferns usually have a highly developed sporophyte generation.
• Pteridophytes have a distinct plant body that is divided into roots, stems, and leaves.
• They have a transport system that allows water and other chemicals to be transported.
• Selaginella, Equisetum, Pteris, and other common examples are only a few.

Gymnosperms (conifers)

• Gymnosperms are vascular plants which produce seeds on cones or cone-like structures.
• Gymnosperm is derived from the Greek words gymnos (naked) and sperma (seed), which literally means seed without a covering.
• It has needle-like or scaly leaves, and these plants are found in areas ranging from the boreal to the desert. Some of these conifers are pines, spruces, and cypresses as well.
• The plant body and vascular tissues of gymnosperms are well-differentiated.
• They produce naked seeds, which are seeds that are not encased in a fruit.
• Gymnosperms include plants such as Cycas, Pinus, Ephedra, and others.

Angiosperms (Flowering Plants)

• Angiosperms are plants with seeds and fruits.
• Angiosperms have flowers for sexual reproduction, attracting insects, birds, and mammals for pollination.
• Angiosperms have numerous forms of adaptations and are the biggest class of plants in the world.
• Angiosperms are vascular plants that produce seeds and have a well-differentiated plant body.
• Angiosperm seeds are contained within the fruits.
• Angiosperms are found all over the world and come in a wide range of sizes.
• Eucalyptus trees grow to be around 100 meters tall, while Wolffia plants grow to be about 0.1 cm tall.
• According to the number of cotyledons contained in the seeds, angiosperms are further split into monocotyledons and dicotyledons.
• Mango, rose, tomato, onion, wheat, maize, and other common examples.

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