Parts Of A Seed

Edited By Irshad Anwar | Updated on Jul 02, 2025 07:09 PM IST

A seed is a well-developed, fertilised ovule that comprises an embryonic plant together with a nutrient-rich endosperm enclosed within a protective outer coat. Being the principal reproductive unit of flowering plants, it provides for the propagation of the plant species. Seeds are of great importance in the reproduction of plants since they have the information that produces a new generation of plants.

This Story also Contains

What are Seeds?
Role of Seeds in Plant Reproduction
Types of Seeds
Structure of a Seed
Process of Germination of Seeds
Special Adaptation of Some Seeds
Importance of Seeds In Agriculture and Ecology
MCQs on Parts of a Seed
Recommended Video On 'Parts Of A Seed'

Parts Of A Seed

The various parts of a seed are- endosperm, the seed coat, and the embryo. They allow for the distribution of plant species in different environments and therefore help in the survival and adaptation of species. The parts of a seed are an important topic in the field of biology.

What are Seeds?

Seeds are units of reproduction in flowering plants developed after fertilisation, encapsulating the embryo, endosperm, and seed coat. They provide a very effective means of propagation of plant species by helping plants reproduce, disperse, and further ensure genetic diversity. They also provide plants with the capability to undergo seed dormancy, thus surviving adverse conditions.

Role of Seeds in Plant Reproduction

Seeds become the most important means of reproduction in plants, as they are dispersed and germinate to produce new plants that carry the further continuity and spread of species in different environments. Another important function is in providing genetic variation, which is very important for plant adaptation and evolution. The main constituents of a seed include the seed coat, the embryo, and the endosperm. The seed coat is responsible for protecting the seed from injuries and pathogens; the embryo gives rise to a new plant; and the endosperm contains most of the energy-rich nutrients needed by the growing embryo for its growth and development.

Types of Seeds

There are broadly two kinds of seeds. They are mainly classified based on the number of cotyledons present.

Monocotyledons (Monocots)	Dicotyledons (Dicots)
One cotyledon, generally thin and grassy in appearance.	Two cotyledons are usually broad and visible as the seed germinates.
Parallel leaf venation with veins running in straight lines directly across the length of the leaf.	Reticulate venation is a network of interconnecting veins in the leaf.
Fibrous root system with many thin roots extending out from the plant stem base.	Tap root type root system, where one primary root grows downward and smaller roots branch off laterally from this main root.
Vascular bundles are scattered around the stem, with no particular pattern.	Vascular bundles in a ring in the stem produce an evident pattern.
Examples include Wheat, corn, rice, barley, lilies, onions	Examples are Bean, pea, tomato, oak, rose

Structure of a Seed

A seed typically consists of three main parts: the seed coat (outer protective covering), the embryo (young plant), and the endosperm (food reserve). In dicots, the embryo has two cotyledons, while in monocots, it has one. The structure of the seed is described below:

Seed Coat (Testa)

The outer protective layer is mainly composed of cellulose and lignin, and so provides mechanical strength.
Other layers may be formed, for example, the tegmen, which adds to protection.
Physically protects the embryo from mechanical damage, desiccation and attack by microorganisms.
May act to regulate the amount of water taken up during germination, preventing germination until suitable conditions are present for the seed to grow into a healthy plant.

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Types Of Seed Coats

Thin: Water and air can pass through, but they germinate relatively quickly.
Thick: More highly protective, but the seed may need special conditions to break dormancy.
Hard: Physically very resistant; germination accomplished by mechanical or chemical force.
Soft: It forms a minimal physical barrier to germination and is most common in seeds that begin germinating shortly after dispersal.

Embryo

Plumule: This is the embryonic shoot that will produce the plant's stem and leaves.
Radicle: This is the embryonic root that will become the plant's primary root.
Cotyledons: Structures that feed the developing seedling.

Plumule

That part of the embryo will develop into the stem and often bends after the cotyledons have been raised from beneath the earth's surface.
May push the cotyledons up out of the soil.

Radicle

That part of the embryo becomes the primary root of the plant.
Anchors the seedlings in the soil and starts to absorb water and mineral elements.

Cotyledons

The cotyledons supply food to the developing embryo until the plant has developed to the point of carrying on photosynthesis satisfactorily.
In monocots, this single cotyledon is known as the scutellum.
In dicots, the two cotyledons store and sometimes even produce nutrients for the developing plant.

Endosperm

Endosperm is a nutritive tissue that develops during seed formation and provides nourishment to the growing embryo.
Acts as a food reserve that is rich in carbohydrates, proteins, and lipids.

Types Of Endosperms

Nuclear: Nucleus-free division with no formation of a cell wall initially.
Cellular: The cell walls are formed just after the nuclear division.
Helobial: A combination of nuclear and cellular types. This is common in monocots. Has very high nutritional value.

Process of Germination of Seeds

Seed germination begins when a seed absorbs water, activating enzymes that convert stored food into energy for growth. The radicle emerges first to form the root, followed by the plumule, which develops into the shoot. The germination process is explained below:

Stages of Seed Germination

Imbibition: Water absorption of the seed causes it to swell, breaking the seed coat.
Metabolism Activation: Biochemical processes initiate after the activation of enzymes and respiration.
Emergence of Radicle and Plumule: The radicle grows downwards into the soil, while the plumule grows upwards towards light.

Factors Affecting Germination

Water: Metabolic processes require water, which further functions to soften the seed coat.
Temperature: Species have temperature optima; some temperatures have to be present for enzymatic activity.
Oxygen: Cellular respiration requires oxygen for energy generation.
Light: Induces germination in some species, and may act as a signal for some seeds.

Special Adaptation of Some Seeds

Some seeds have adaptations like wings for wind dispersal, hooks for animal attachment, or dormancy mechanisms to survive harsh conditions. These features enhance their chances of survival and successful germination. The special adaptation of some seeds is given below:

Seed Dormancy

Causes: impermeable seed coat; hormonal: growth-inhibiting hormone; lack of a suitable environment, temperature, and water.
Dormancy release: Natural: weathering, microbial action, and passage through the alimentary canal of an animal.
Artificial Scarification: mechanical scratching or breaking of the seed coat.
Stratification: exposure of seeds to cold temperature.

Seed Dispersal Mechanism

Water: Seeds that are buoyant, thus capable of floating, for example, a coconut
Animal: Seeds with hooks or the fruit is edible, for example, burrs or berries
Explosion: Seeds explosively shoot out of the pod, for example, touch-me-not or squirting cucumber

Importance of Seeds In Agriculture and Ecology

Seeds are essential for crop production and food security in agriculture. Ecologically, they support plant biodiversity, help in reforestation, and sustain various food chains by serving as food for animals. The details are given below:

Role in Crop Production

Seeds form the basis of food crops.
They are selected for particular attributes and breeding.
Food security is guaranteed through the consistent and reliable production of crops.

Seed Banks and Conservation

Seed banks store seeds for conserving diversity or against plant extinction, thereby protecting genetic information in seed-preserved form.
This is important for basic and applied research on plant species and their reintroduction into the ecosystem.

Ecological Impact

As agents for reproduction in plants, seeds maintain the viability of plant species and, hence, are very important in maintaining biodiversity.
New plant taxa become established in new sites since seeds become dispersed and germinate, a route toward achieving ecological equilibrium.

MCQs on Parts of a Seed

Q1. Given figure represents longitudinal section of a monocotyledonous embryo.

Monocot embryo

Identify the parts labelled as A , B , C and D from the list and select the correct option

1) scutellum

2) Coleoptile

3) Shoot apex

4) Epiblast

5) Radicle

6) Root cap

7) Coleorhiza

Option 1: 1,6,7,2

Option 2: 2,7,5,1,

Option 3: 4,3,6,7

Option 4: 3,7,6,2

Correct Answer: (2) 2,7,5,1,

Explanation:

In maize, the seed coat is fused with the pericarp, and the major part of the grain is occupied by a large endosperm which is rich in starch. The endosperm has one to three layered peripheral protein layers called aleurone layers which separate the embryo from the endosperm.

Hence the correct answer is Option 2) 2,7,5,1,

Q2. Monocotyledonous seeds are endospermic but ____ are non- endospermic

Option 1: Wheat

Option 2: Rice

Option 3: Maize

Option 4: Orchids

Correct Answer: (4) Orchids

Explanation:

Monocotyledonous seeds - Monocotyledonous seeds are endospermic but some are non-endospermic (orchid). Monocotyledonous seeds are endospermic, storing food in the endosperm for the developing embryo, but some, like orchids, are non-endospermic. They have a single cotyledon, called the scutellum, which aids in nutrient absorption. The outer covering consists of the seed coat, which protects the embryo. Examples include seeds of grasses like wheat, maize, and rice.

Hence, the correct answer is option 4) Orchids

Q3. Seeds develop after _____ from the _____.

Option 1: Fertilization; ovary

Option 2: Triple fusion; ovule

Option 3: Fertilization; ovule

Option 4: None of these

Correct Answer: (3) Fertilization; ovule

Explanation:

Seeds develop after fertilization from the ovule. Seeds develop after fertilization from the ovule, which contains the embryo and stored food. The outer integuments of the ovule form the seed coat, providing protection. Seeds serve as a vital means of reproduction and dispersal in angiosperms. They can remain dormant under unfavourable conditions, ensuring the survival of the species.

Hence, the correct answer is option 3 - Fertilization; ovule.

Read more:

Pollen-Pistil Interaction & Outbreeding Devices	Artificial Hybridisation in Plants - Emasculation and Bagging
Self incompatibility	Post Fertilisation - Events and Changes in Flowering Plants
Microsporogenesis	Pollination

Recommended Video On 'Parts Of A Seed'

Frequently Asked Questions (FAQs)

1. What are the main parts of a seed?

The three primary parts of a seed are the seed coat, embryo, and endosperm.

2. What are the main parts of a seed?

The main parts of a seed are the seed coat, embryo, and endosperm. The seed coat is the protective outer layer, the embryo is the young plant, and the endosperm is the food storage tissue.

3. How does seed germination take place?

Seed germination takes place through successive stages: imbibition, activation of metabolism, and emergence of radicle and plumule.

4. How are monocot and dicot seeds different?

Monocot seeds contain one cotyledon; a dicot, and two. They also differ in their germination process and structure.

5. What is the significance of the seed coat?

The seed coat provides protection to the seed from physical injuries and entry of the pathogen and regulates events of germination.

6. What are some of the factors that result in germination from seeds?

Water, temperature, oxygen, and light act to increase seed germination.

7. How does seed size relate to embryo development and survival?

Seed size often correlates with the amount of stored nutrients and embryo size. Larger seeds typically contain more nutrients, supporting longer periods of growth before the seedling becomes self-sufficient. This can increase survival rates in challenging environments.

8. How does seed coat coloration relate to seed function and ecology?

Seed coat coloration can serve various functions, including camouflage from predators, attraction of dispersers, temperature regulation, and protection from UV radiation. The color can also indicate seed maturity or viability in some species.

9. How does the structure of a seed affect its longevity in soil?

Seed longevity in soil is influenced by factors like seed coat thickness and permeability, internal chemical composition, and size. Seeds with hard, impermeable coats and low moisture content tend to survive longer in soil, forming seed banks.

10. What is the significance of the caruncle in some seeds?

The caruncle is a fleshy outgrowth near the hilum in some seeds. It can attract animals for seed dispersal, absorb water to aid germination, or contain oils and other compounds that may deter predators or assist in seed-soil contact.

11. How does seed coat impermeability affect germination?

Seed coat impermeability can delay germination by preventing water uptake and gas exchange. This is a form of physical dormancy that protects the seed until environmental conditions (like abrasion or temperature fluctuations) break down the seed coat barrier.

12. How does the micropyle contribute to seed germination?

The micropyle is a small pore in the seed coat through which water enters during imbibition, initiating germination. It also allows oxygen to reach the embryo and can serve as an exit point for the emerging radicle.

13. How does the radicle differ from other roots?

The radicle is the embryonic root within the seed. It's the first part of the seedling to emerge during germination, becoming the primary root from which other roots develop. Unlike later roots, it originates directly from the embryo.

14. What is the significance of the seed's hypocotyl?

The hypocotyl is the part of the embryo between the radicle and the cotyledons. During germination, it elongates and pushes the cotyledons above ground in epigeal germination, or remains short in hypogeal germination, affecting the seedling's initial growth pattern.

15. What is the plumule and why is it important?

The plumule is the embryonic shoot found within the seed. It's important because it develops into the first true leaves and stem of the new plant, enabling photosynthesis and further growth after germination.

16. What role does the aleurone layer play in seeds?

The aleurone layer is a specialized tissue found between the endosperm and seed coat in some seeds. It produces enzymes that break down stored nutrients in the endosperm during germination, making them available to the growing embryo.

17. What is the importance of the suspensor in seed development?

The suspensor is a structure that connects the developing embryo to the parent plant. It plays a crucial role in early embryo development by providing nutrients and growth regulators, and positioning the embryo within the developing seed.

18. What role does the funiculus play in seed development?

The funiculus is the stalk that attaches the developing seed to the placenta of the ovary. It provides a pathway for nutrients and water to reach the developing seed. After seed maturation, it detaches, leaving the hilum scar on the seed coat.

19. What role does the chalaza play in seed development and structure?

The chalaza is the base of the ovule where the funiculus and integuments converge. In the mature seed, it can be visible as a small area opposite the micropyle. It's significant in seed development as the point where nutrients enter the developing seed from the parent plant.

20. How do seeds store energy for germination?

Seeds store energy in various forms within the endosperm or cotyledons. Common storage molecules include starch (carbohydrates), proteins, and lipids (oils). These energy-rich compounds are broken down during germination to fuel the growing embryo.

21. How do seed air spaces contribute to seed function?

Air spaces within seeds can serve multiple purposes, including aiding in buoyancy for water dispersal, providing insulation against temperature extremes, and facilitating gas exchange during germination. They can also reduce seed weight, assisting in wind dispersal.

22. What is the significance of seed symmetry in relation to embryo positioning?

Seed symmetry, which can be radial or bilateral, is often related to the positioning of the embryo within the seed. This positioning affects how the seedling emerges during germination and can influence the seed's orientation in the soil, potentially impacting germination success and early seedling establishment.

23. How do seed structures in gymnosperms differ from those in angiosperms?

Gymnosperm seeds differ from angiosperm seeds in several ways. They lack a true fruit and often have a thin seed coat. The female gametophyte tissue serves a similar function to endosperm in angiosperms. Gymnosperm seeds often have structures adapted for wind dispersal, such as wings, and may have specialized structures for pollen capture.

24. How does the structure of orchid seeds differ from typical angiosperm seeds?

Orchid seeds are unique in their structure. They are extremely small and lack endosperm. Instead of stored nutrients, they rely on symbiotic relationships with fungi for germination and early growth. The embryo is surrounded by a loose, balloon-like seed coat that aids in wind dispersal.

25. What is the significance of the epistase in some seeds?

The epistase is a cap-like structure found at the micropylar end of some seeds. It can play a role in controlling water uptake during germination and may be involved in regulating dormancy. In some species, it detaches or ruptures to allow radicle emergence during germination.

26. What role does the nucellus play in seed development and mature seed structure?

The nucellus is the central tissue of the ovule from which the embryo sac develops. In some seeds, remnants of the nucellus persist as the perisperm, a food storage tissue. Even when not persistent, the nucellus plays a crucial role in early seed development by nourishing the developing embryo and endosperm.

27. Why do some seeds have a hard seed coat while others have a soft one?

The hardness of the seed coat is an adaptation to different environmental conditions and dispersal strategies. Hard seed coats provide better protection against harsh environments and predators, while soft seed coats allow for quicker germination in favorable conditions.

28. What is seed dormancy and how does it relate to seed structure?

Seed dormancy is a state in which seeds do not germinate even under favorable conditions. It's often regulated by the seed coat and chemical inhibitors in the endosperm or embryo, allowing seeds to survive until conditions are optimal for growth.

29. How does the structure of a seed contribute to its dispersal?

Seed structures can aid in dispersal through various adaptations. For example, wings or hairs on the seed coat can help with wind dispersal, while hard seed coats can protect seeds during animal dispersal through ingestion and excretion.

30. What is the purpose of the perisperm in some seeds?

The perisperm is a nutritive tissue derived from the nucellus of the ovule. In seeds that have it, it serves as an additional or alternative food storage tissue to the endosperm, providing nutrients to the developing embryo during germination.

31. What is the function of the scutellum in grass seeds?

The scutellum is a modified cotyledon found in grass seeds. It acts as an interface between the embryo and the endosperm, secreting enzymes to break down endosperm nutrients and absorbing the resulting molecules to feed the growing embryo.

32. What is the difference between endosperm and cotyledons?

Endosperm is a nutritive tissue found in many seeds, while cotyledons are the first leaves of the embryo. In some plants, cotyledons take on the role of food storage, replacing the endosperm. Monocots typically have one cotyledon, while dicots have two.

33. How do dicot and monocot seeds differ in structure?

Dicot seeds typically have two cotyledons, while monocot seeds have one. Dicot embryos usually have a distinct plumule and radicle, whereas monocot embryos often have less differentiated structures. The endosperm is usually more prominent in monocot seeds.

34. How does the seed coat protect the embryo?

The seed coat protects the embryo by providing a physical barrier against mechanical damage, regulating water uptake, and defending against pathogens and pests. It also helps control seed dormancy and germination timing.

35. What is the function of the hilum in a seed?

The hilum is the scar on the seed coat where it was attached to the ovary wall. It serves as the main point for water absorption during germination and can also play a role in seed dispersal mechanisms.

36. How do recalcitrant seeds differ from orthodox seeds in terms of structure and storage?

Recalcitrant seeds have high moisture content and remain metabolically active, unlike orthodox seeds which can be dried and stored. This difference is reflected in their structure, with recalcitrant seeds often having less developed protective structures and more active embryos.

37. How do polyembryonic seeds differ from typical seeds?

Polyembryonic seeds contain multiple embryos within a single seed coat, unlike typical seeds with one embryo. This can result from various processes, including the division of a single embryo or the development of embryos from different cells within the ovule.

38. What is the function of the raphe in anatropous seeds?

The raphe is a ridge on the seed coat formed by the fusion of the funiculus with the outer integument in anatropous (inverted) ovules. It can play a role in seed dispersal and sometimes contains vascular tissue that supplied nutrients to the developing seed.

39. What is the role of the pericarp in seeds that retain it?

In seeds that retain the pericarp (fruit wall), it can provide additional protection, aid in dispersal, or contribute to seed dormancy. The pericarp may also contain chemicals that inhibit or promote germination under specific conditions.

40. What is the function of the lens (strophiole) in some legume seeds?

The lens or strophiole is a specialized structure in some legume seeds that acts as a water gap. It can break physical dormancy by allowing water entry when environmental conditions are suitable, initiating the germination process.

41. What is the role of the tegmen in seed structure?

The tegmen is the inner layer of the seed coat, lying beneath the outer layer (testa). It provides additional protection to the embryo and can play a role in controlling water uptake and gas exchange during seed development and germination.

42. How do cotyledons in some seeds transition from storage organs to photosynthetic leaves?

In epigeal germination, cotyledons emerge above ground and often turn green, transitioning from storage organs to temporary photosynthetic leaves. This process involves the breakdown of stored nutrients and the development of chloroplasts, supporting the seedling until true leaves form.

43. How does the arrangement of storage tissues in the seed affect mobilization during germination?

The arrangement of storage tissues (endosperm, perisperm, or cotyledons) affects the efficiency of nutrient mobilization during germination. Proximity to the embryo, vascularization, and the presence of specialized tissues like the aleurone layer all influence how quickly and effectively stored nutrients can be accessed.

44. What is the importance of the embryonic axis in seed structure?

The embryonic axis is the central part of the embryo that gives rise to the new plant. It includes the radicle (embryonic root), plumule (embryonic shoot), and hypocotyl. The orientation and development of the embryonic axis determine the initial growth direction of the seedling.

45. How do some seeds achieve long-term dormancy through structural adaptations?

Long-term dormancy can be achieved through structural adaptations such as extremely hard or impermeable seed coats, specialized dormancy-maintaining tissues, or complex interactions between the embryo and surrounding tissues that prevent premature germination until specific environmental triggers are met.

46. How do seed appendages like wings, hairs, or arils relate to seed dispersal strategies?

Seed appendages are adaptations for specific dispersal methods. Wings and hairs aid in wind dispersal by increasing surface area and reducing weight. Arils are fleshy appendages that often attract animals for seed dispersal. These structures reflect the plant's evolutionary adaptations to its environment and dispersal agents.

47. What is the role of the transfer layer in some seeds?

The transfer layer is a specialized tissue found in some seeds, typically located between the maternal tissue and the endosperm or embryo. It facilitates the efficient transfer of nutrients from the parent plant to the developing seed, playing a crucial role in seed filling and development.

48. How do seed structures contribute to seed longevity in extreme environments?

Seed structures contribute to longevity in extreme environments through various adaptations. These can include highly impermeable seed coats to prevent water loss in arid conditions, antifreeze proteins in the embryo for cold tolerance, or specialized compounds in the endosperm that provide protection against heat or radiation damage.

49. What is the function of the operculum in some seeds?

The operculum is a lid-like structure found in some seeds, particularly in certain aquatic plants. It functions as a controlled opening mechanism during germination, allowing the embryo to emerge while still providing protection. This structure can also play a role in regulating seed dormancy and water uptake.

50. How does seed coat texture relate to seed dispersal and germination strategies?

Seed coat texture can significantly influence both dispersal and germination. Rough or sticky textures may aid in animal dispersal by adhering to fur or feathers. Smooth textures might facilitate wind or water dispersal. Textural features can also affect water absorption rates and soil contact, influencing germination timing and success.

51. What is the role of the hypostase in seed development?

The hypostase is a specialized tissue located at the chalazal end of some seeds. It plays a role in controlling nutrient flow into the developing seed and can contribute to the formation of the seed coat. In some species, it may also be involved in regulating seed dormancy.

52. How do seed structures in parasitic plants differ from those in autotrophic plants?

Seeds of parasitic plants often have reduced structures compared to autotrophic plants. They may lack endosperm or have minimal food reserves, as they rely on host plants for nutrition. Their embryos are often less differentiated, and they may have specialized structures for attaching to or penetrating host tissues upon germination.

53. How do seed structures adapt to facilitate germination in aquatic environments?

Seeds adapted for aquatic germination may have structures that enhance buoyancy, such as air-filled cavities or spongy tissues. They might also have modified seed coats that allow for gas exchange underwater or structures that anchor the seed to substrates. Some aquatic seeds have adaptations to protect the embryo from excess water absorption.

54. What is the function of the aril in seeds that have this structure?

The aril is a fleshy outgrowth that partially or completely covers some seeds. It often serves to attract animals for seed dispersal by providing a nutritious food source. Arils can also play roles in seed protection, water retention, or even deterring certain predators through chemical compounds.

55. How do seed structures contribute to seed dormancy breaking mechanisms?

Seed structures play crucial roles in dormancy breaking mechanisms. The seed coat may have specialized regions that respond to environmental cues like temperature fluctuations or light. Internal structures like the endosperm or aleurone layer can produce or store hormones and enzymes that break dormancy when activated. The embryo itself may have adaptations that respond to specific environmental triggers, initiating germination when conditions are favorable.