Angiosperms – Definition, Characteristics, Examples & Classification

Angiosperm is an important chapter in NCERT 2022 class 12 Biology. Students will find all the necessary details related to the definition, characteristics, classification and examples of angiosperms. This chapter is important for both boards and entrance examinations. Students can follow the PDF of this chapter on this page to study offline. NCERT books cover all the topics appropriately and explain all the topics in the most simplified manner. NCERT has decided to conduct the 12th board examination in two terms, there is no official notification on the dates of term- 2 examination. Follow this page to get all the information on any updates released by NCERT.

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Angiosperms: Definition

Angiosperms are flower-producing plants, and they belong to one of the vital groups of plants having seeds. Angiosperms (Greek Angeion – vessels; Sperma – seed) are also grouped as Spermatophyta and are popularly known as flowering plants. They are the highly evolved plant groups among the plant kingdom. Angiosperms are one of the most diverse and most significant groups of a plant in the universe.

Angiosperms: Examples

Few examples of Angiosperms are:
1. Grains like rice, wheat, and corn, etc.
2. Vegetables like tomatoes, eggplants, potatoes, etc.
3. Flowers like roses, lilies, sunflowers, etc.
4. Fruits like apple, guava, jackfruit, etc.
5. Trees like Magnolia, oak, maple, etc.
6. Timber-yielding plants like teak, mahogany, etc.
7. Medicinal plants like Atropa, Cinchona, Rauwolfia, etc.

Angiosperms: Characteristics

Angiosperms are the most advanced and beneficial group of plants on the planet. They have diverse characteristics. The characteristics of angiosperms are:
1. Occurrence: Angiosperms are found in all environments, up to \(6000\,{\rm{m}}\) height (from mean sea level). They are found in high temperatures, cold deserts, freshwater, saline water, tropical and temperate climates.
2. Size: Smallest Angiosperm is Wolffia \(\left( {0.1\,{\rm{mm}}} \right),\) and the tallest is Eucalyptus.
3. Plant Body: The plant body is sporophytic and diploid.
4. Habit: Angiosperms show various habits, like herbs, shrubs, trees, liana, climber, creeper, twinner, etc.
5. Life Span: The life span varies to a large extent. Boerhaavia repens of the Sahara desert live for only two weeks, while Lomatia tasmanica has been reported to survive for more than \(300\) years.
6. Roots: They have roots developed from radicles and form tap root systems. In some Angiosperms, adventitious roots are formed from other body parts, like leaves, stems. 
7. Stems: The first stem develops from plumule. Angiosperms have various modifications of stem, underground, sub-aerial, aerial.
8. Leaves: They are for photosynthetic activities and develop from nodes on the stem. Some plants also show a modification in leaves.
9. Xylem: In most cases, the Xylem of Angiosperms have vessels, tracheid, xylem parenchyma and xylem fibres (Wood). The Winteraceae have no vessels in their xylem.
10. Phloem: In most cases, Phloem of Angiosperms have sieve elements, companion cells, phloem parenchyma, and phloem fibres (Bast).
11. Flower: These are the most attractive, complex reproductive structures of Angiosperms. These are most peculiar in Angiosperms only. It is, in most cases, an aggregate of both microsporophylls (stamens) and megasporophylls (carpels). The flower in the plant is a reproductive organ.
12. Flowers are modified shoots specialised for reproduction.
13. Microsporophyll: It is called the stamen. This has three parts, microsporangium, connective, and filament.
14. Megasporophyll: It is called carpel. This has a stigma, style, and ovary that has ovules.
15. Pollination: It is unique in Angiosperms as it involves various biotic and abiotic agents for the transfer of pollen from the anther to the stigma of the flower.
16. Gametophyte: This stage is highly reduced and represented by cells. Male gametophyte is represented by single cells. The female gametophyte is called an embryo sac which contains female gametes.
17. Double fertilization: This is a unique feature that is not present in any other plant group. One of the two male gametes proceeds for syngamy, and the second proceeds for triple fusion and produces primary endosperm nucleus (PEN), which develops into endosperm.
18. Endosperm: This is a product of double fertilization which produces triploid tissue for the nourishment of the growing embryo.
19. Fruits: They are the ripened and fertilised ovary. They cover the seed. Unlike Gymnosperms, all Angiosperms have covered seeds.
20. Seeds: These are the fertilised ovules that are inside the fruit. Seeds develop into a new plant.

Angiosperms: Classification

Angiosperms can be classified into two classes: Dicotyledonae and Monocotyledonae.
1. Dicots are those angiosperms that have a pair of leaves or cotyledons present in the embryo of the seed.
2. Monocots are the angiosperms that have only one embryonic leaf or cotyledon present in the seed.

Angiosperms: Reproduction

Angiosperms are plants that bear flowers, fruits, and seeds.
1. Reproduction in angiosperms is mainly sexual. Flowers are considered to play a significant role in the process of reproduction as they contain the reproductive structures called stamen and pistil that produce the haploid male and female gametes.
a. Flowers are highly modified and compressed shoots that contain fertile male and female spore-bearing leaves (sporophylls).
2. Pollination is one vital step in the reproduction of Angiosperms, as it brings the male and female gametes together.
3. During pollination, pollen grains from the anther to the stigma of the same or the different flowers but the same species. This transfer of pollen can occur naturally or with the help of pollinating agents.
a., Unlike Gymnosperms, flowering plants have adapted for various biotic and abiotic pollinators. Wind and water are abiotic pollinators. Birds, honey bees, moths, butterflies, wasps, snails, snakes, ants, and many other animals are biotic pollinating agents.
4. Now, the pollen grain germinates on the stigma forming a pollen tube that carries two male gametes to the embryo sacs, going through the tissue of stigma and style.
5. The microspores divide mitotically to form two male gametes (from the generative cells).
6. One of the male gametes \(\left( n \right)\) fuses with the egg nucleus \((n)\) and form the diploid zygote \(\left( {2n} \right).\)
a. This is the first fertilization process which is also known as syngamy.
7. The other male gamete moves to the central cell. It fuses with the polar nuclei or the secondary nucleus (formed by the fusion of \(2\) polar nuclei and is diploid) and forms a triploid nucleus called the primary endosperm nucleus (PEN).
a. This process is known as the double fertilization process and triple fusion.
8. Since two sets of fertilization take place, that is syngamy and triple fusion; it is called double fertilization. It is unique to flowering plants.
9. The ovule gradually transforms into a seed, and the ovary becomes the fruit, and the non-reproductive structures like petals, sepals, etc., of the flowers, fall off.

Angiosperms: Uses

Angiosperm has a vital use in day-to-day life as it produces so many essential components which are necessary for the survival of humankind and animals. They have both economic and ecological usage.
The major uses of angiosperms can be showcased in the below table:

Angiosperms and Gymnosperms – Comparison

Let us now compare Gymnosperms and Angiosperms.

Do You Know?

1. Angiosperms are so ancient that they coexisted even during the period of dinosaurs. 
2. Eucalyptus regnans, also known as Centurion, is the world’s tallest angiosperm.
3. The smallest angiosperm is Wolffia arrhiza.
4. All orchids have dust seeds, which cannot germinate in nature. They need fungal association for germination.

Summary

Angiosperm is one of the largest groups of plants on this earth. They produce flowers, fruits, and seeds. They are omnipresent and are found in vivid habits and habitats. They show the most advanced characters which are often not found in other plant groups. They produce the most beautiful flowers which are their reproductive organs. Their seeds are covered and well protected inside the fruit. Angiosperms have enormous economic importance.

Frequently Asked Question (FAQs) on Angiosperms

Here are some of the frequently asked questions on Angiosperms:
Q.1. What are the three examples of angiosperms?
Ans: The three examples of angiosperms are Apple, Rose, and Rice.

Q.2. What are the two main types of angiosperms?
Ans: The two types (classes) of angiosperms are Monocotyledonae and Dicotyledonae.

Q.3. What is the difference between angiosperms and gymnosperms?
Ans: Angiosperms have seeds that are enclosed within the ovary or the fruit, while gymnosperms have no flowers or fruits and have unenclosed seeds on the scales of leaves.

Q.4. How do you identify angiosperms?
Ans: The main identity of angiosperms is that all angiosperms will have flowers at some stage in their life.

Q.5. What is the simple definition of angiosperms?
Ans: The plant which produces flowers is called angiosperm.