A seed is a plant's characteristic reproductive body in gymnosperms and angiosperms. It contains an embryo, sometimes with food stores for early growth, all encased in a protective coat called a testa. Seeds serve various functions, including multiplication, perennation, dormancy, and dispersal. They have a stored reserve of nutrients and a multicellular structure that allows for adaptations for dispersal. After fertilization, the ovule develops into a seed. The seed coat comes from the ovule's protective integuments. Seeds are also economically important as sources of foods such as cereal grains and nuts .

Why are seeds important for plants?

Seeds are vital for plants because they ensure the continuation of plant species. They consist of an embryo, a food supply, and a protective coat. Seeds allow plants to multiply, survive harsh conditions, remain dormant, and disperse to new locations. Seed dispersal is important for a plant species' survival, increasing the chances that some seeds will find a suitable place to grow. It also reduces competition between parent plants and their offspring for resources like sunlight and nutrients. Seeds facilitate the colonization of new areas and the reestablishment of species after disturbances. Adaptations like plumes or wings aid in seed dispersal by wind, water, or animals.

How do seeds form in flowering plants?

In flowering plants, seed formation begins with pollination , where pollen grains transfer from the stamen to the pistil's stigma. The pollen grain germinates, and a pollen tube grows down to the ovule within the pistil. Double fertilization occurs when one sperm cell fuses with the egg cell to form a zygote, which develops into the embryo. The other sperm cell combines with polar nuclei, initiating the formation of the endosperm , a food reserve tissue. The ovule then transforms into a seed, containing the embryo and endosperm, enclosed by a protective seed coat. The ovary develops into the fruit, which encloses the seeds.

What are the main parts of a seed?

The main parts of a seed include the embryo, endosperm, and seed coat.

How does a seed grow into a new plant?

The growth of a seed into a new plant begins with germination , which is initiated by environmental factors such as water, temperature changes, and light exposure. The process includes: * The seed absorbing water and swelling, which causes the embryo inside to start growing. * The primary root, or radicle, emerging first and growing downward into the soil, which anchors the seedling. * The shoot growing upward toward the light. * Cell division occurring in the radicle and young shoot. * The seedling depending on food reserves from the parent plant until it becomes self-sufficient. * The seedling responding to gravity, with the radicle growing downward (positively geotropic) and the shoot growing upward (negatively geotropic). * The shoot showing a strong attraction to light, or a positive phototropism.

What factors help seeds germinate and develop successfully?

Several environmental factors influence seed germination and development, including water, temperature, light, and oxygen. Water After a period of dormancy, seeds need to absorb water for cells to rehydrate and expand, which triggers metabolic processes necessary for germination. Temperature Seeds require specific temperatures, and alternating temperatures can ensure germination at appropriate soil depths. Light Some seeds are sensitive to light, with germination either stimulated or inhibited by it. Oxygen Oxygen is needed for metabolic processes to resume after water uptake. A hard seed coat can prevent gas exchange, so the seed coat must be punctured or removed to allow oxygen to reach the embryo. Seed dormancy can be influenced by a hard seed coat, which may prevent water from entering or impede gas exchange. Some seeds require a period of afterripening, often needing a specific duration of cold temperatures.

seed

Images & Videos

Close-up of a toucan with a large yellow and black bill holding a piece of fruit or nut in its beak, Amazon, Brazil.

At a Glance

seed summary

seed

plant reproductive part

Written by

Hans Lambers

Fact-checked by

Britannica Editors

Last updated

Oct. 15, 2026 •History

Top Questions

What is a seed?
A seed is a plant's characteristic reproductive body in gymnosperms and angiosperms. It contains an embryo, sometimes with food stores for early growth, all encased in a protective coat called a testa.

Seeds serve various functions, including multiplication, perennation, dormancy, and dispersal. They have a stored reserve of nutrients and a multicellular structure that allows for adaptations for dispersal. After fertilization, the ovule develops into a seed. The seed coat comes from the ovule's protective integuments.

Seeds are also economically important as sources of foods such as cereal grains and nuts.
3 Britannica Sources
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
Why are seeds important for plants?
Seeds are vital for plants because they ensure the continuation of plant species. They consist of an embryo, a food supply, and a protective coat. Seeds allow plants to multiply, survive harsh conditions, remain dormant, and disperse to new locations.

Seed dispersal is important for a plant species' survival, increasing the chances that some seeds will find a suitable place to grow. It also reduces competition between parent plants and their offspring for resources like sunlight and nutrients. Seeds facilitate the colonization of new areas and the reestablishment of species after disturbances. Adaptations like plumes or wings aid in seed dispersal by wind, water, or animals.
5 Britannica Sources
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
How do seeds form in flowering plants?
In flowering plants, seed formation begins with pollination, where pollen grains transfer from the stamen to the pistil's stigma. The pollen grain germinates, and a pollen tube grows down to the ovule within the pistil.

Double fertilization occurs when one sperm cell fuses with the egg cell to form a zygote, which develops into the embryo. The other sperm cell combines with polar nuclei, initiating the formation of the endosperm, a food reserve tissue. The ovule then transforms into a seed, containing the embryo and endosperm, enclosed by a protective seed coat. The ovary develops into the fruit, which encloses the seeds.
6 Britannica Sources
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
What are the main parts of a seed?
The main parts of a seed include the embryo, endosperm, and seed coat.
- The embryo is the young, developing plant. It consists of the radicle (root), the plumule (shoot), and one or more cotyledons (seed leaves).
- The endosperm is a nutrient-rich tissue that nourishes the embryo. In some seeds, the endosperm is fully absorbed by the time the seed is mature, and the cotyledons take over the role of nourishing the embryo. In other seeds, the endosperm is still present during germination.
- The seed coat, or testa, is the outer protective covering of the seed. It protects the embryo from damage and desiccation. The seed coat may also have a small opening called the micropyle, which allows water to enter the seed. The hilum is a scar on the seed that marks where it was attached to the ovary.
4 Britannica Sources
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
How does a seed grow into a new plant?
The growth of a seed into a new plant begins with germination, which is initiated by environmental factors such as water, temperature changes, and light exposure.

The process includes:
* The seed absorbing water and swelling, which causes the embryo inside to start growing.
* The primary root, or radicle, emerging first and growing downward into the soil, which anchors the seedling.
* The shoot growing upward toward the light.
* Cell division occurring in the radicle and young shoot.
* The seedling depending on food reserves from the parent plant until it becomes self-sufficient.
* The seedling responding to gravity, with the radicle growing downward (positively geotropic) and the shoot growing upward (negatively geotropic).
* The shoot showing a strong attraction to light, or a positive phototropism.
7 Britannica Sources
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
What factors help seeds germinate and develop successfully?
Several environmental factors influence seed germination and development, including water, temperature, light, and oxygen.
- Water After a period of dormancy, seeds need to absorb water for cells to rehydrate and expand, which triggers metabolic processes necessary for germination.
- Temperature Seeds require specific temperatures, and alternating temperatures can ensure germination at appropriate soil depths.
- Light Some seeds are sensitive to light, with germination either stimulated or inhibited by it.
- Oxygen Oxygen is needed for metabolic processes to resume after water uptake. A hard seed coat can prevent gas exchange, so the seed coat must be punctured or removed to allow oxygen to reach the embryo.
Seed dormancy can be influenced by a hard seed coat, which may prevent water from entering or impede gas exchange. Some seeds require a period of afterripening, often needing a specific duration of cold temperatures.
2 Britannica Sources
1. germination
2. seed: Role of the seed coat
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

seed, the characteristic reproductive body of both angiosperms (flowering plants) and gymnosperms (e.g., conifers, cycads, and ginkgos). Essentially, a seed consists of a miniature undeveloped plant (the embryo), which, alone or in the company of stored food for its early development after germination, is surrounded by a protective coat (the testa). Frequently small in size and making negligible demands upon their environment, seeds are eminently suited to perform a wide variety of functions the relationships of which are not always obvious: multiplication, perennation (surviving seasons of stress such as winter), dormancy (a state of arrested development), and dispersal. Pollination and the “seed habit” are considered the most important factors responsible for the overwhelming evolutionary success of the flowering plants, which number more than 300,000 species.

Seed dispersalSeeds and their dispersal mechanisms.

The superiority of dispersal by means of seeds over the more primitive method involving single-celled spores, lies mainly in two factors: the stored reserve of nutrient material that gives the new generation an excellent growing start and the seed’s multicellular structure. The latter factor provides ample opportunity for the development of adaptations for dispersal, such as plumes for wind dispersal, barbs, and others.

Economically, seeds are important primarily because they are sources of a variety of foods—for example, the cereal grains, such as wheat, rice, and corn (maize); the seeds of beans, peas, peanuts, soybeans, almonds, sunflowers, hazelnuts, walnuts, pecans, and Brazil nuts. Other useful products provided by seeds are abundant. Oils for cooking, margarine production, painting, and lubrication are available from the seeds of flax, rape, cotton, soybean, poppy, castor bean, coconut, sesame, safflower, sunflower, and various cereal grains. Essential oils are obtained from such sources as juniper “berries,” used in gin manufacture. Stimulants are obtained from such sources as the seeds of coffee, kola, guarana, and cocoa. Spices—from mustard and nutmeg seeds; from the aril (“mace”) covering the nutmeg seed; from the seeds and fruits of anise, cumin, caraway, dill, vanilla, black pepper, allspice, and others—form a large group of economic products.

The nature of seeds

Angiosperm seeds

Flower anatomyDiagram of the flower of a typical flowering plant (angiosperm).

In the typical flowering plant, or angiosperm, seeds are formed from bodies called ovules contained in the ovary, or basal part of the female plant structure, the pistil. The mature ovule contains in its central part a region called the nucellus that in turn contains an embryo sac with eight nuclei, each with one set of chromosomes (i.e., they are haploid nuclei). The two nuclei near the centre are referred to as polar nuclei; the egg cell, or oosphere, is situated near the micropylar (“open”) end of the ovule.

With very few exceptions (e.g., the dandelion), development of the ovule into a seed is dependent upon fertilization, which in turn follows pollination. Pollen grains that land on the receptive upper surface (stigma) of the pistil will germinate, if they are of the same species, and produce pollen tubes, each of which grows down within the style (the upper part of the pistil) toward an ovule. The pollen tube has three haploid nuclei, one of them, the so-called vegetative, or tube, nucleus seems to direct the operations of the growing structure. The other two, the generative nuclei, can be thought of as nonmotile sperm cells. After reaching an ovule and breaking out of the pollen tube tip, one generative nucleus unites with the egg cell to form a diploid zygote (i.e., a fertilized egg with two complete sets of chromosomes, one from each parent). The zygote undergoes a limited number of divisions and gives rise to an embryo. The other generative nucleus fuses with the two polar nuclei to produce a triploid (three sets of chromosomes) nucleus, which divides repeatedly before cell-wall formation occurs. This process gives rise to the triploid endosperm, a nutrient tissue that contains a variety of storage materials—such as starch, sugars, fats, proteins, hemicelluloses, and phytate (a phosphate reserve).

The events just described constitute what is called the double-fertilization process, one of the characteristic features of all flowering plants. In the orchids and in some other plants with minute seeds that contain no reserve materials, endosperm formation is completely suppressed. In other cases it is greatly reduced, but the reserve materials are present elsewhere—e.g., in the cotyledons, or seed leaves, of the embryo, as in beans, lettuce, and peanuts, or in a tissue derived from the nucellus, the perisperm, as in coffee. Other seeds, such as those of beets, contain both perisperm and endosperm. The seed coat, or testa, is derived from the one or two protective integuments of the ovule. The ovary, in the simplest case, develops into a fruit. In many plants, such as grasses and lettuce, the outer integument and ovary wall are completely fused, so seed and fruit form one entity; such seeds and fruits can logically be described together as “dispersal units,” or diaspores. More often, however, the seeds are discrete units attached to the placenta on the inside of the fruit wall through a stalk, or funiculus.

The hilum of a liberated seed is a small scar marking its former place of attachment. The short ridge (raphe) that sometimes leads away from the hilum is formed by the fusion of seed stalk and testa. In many seeds, the micropyle of the ovule also persists as a small opening in the seed coat. The embryo, variously located in the seed, may be very small (as in buttercups) or may fill the seed almost completely (as in roses and plants of the mustard family). It consists of a root part, or radicle, a prospective shoot (plumule or epicotyl), one or more cotyledons (one or two in flowering plants, several in Pinus and other gymnosperms), and a hypocotyl, which is a region that connects radicle and plumule. A classification of seeds can be based on size and position of the embryo and on the proportion of embryo to storage tissue; the possession of either one or two cotyledons is considered crucial in recognizing two main groups of flowering plants, the monocotyledons and the eudicotyledons.

Explore Britannica Premium!

The trusted destination for professionals, college students, and lifelong learners.

Seedlings, arising from embryos in the process of germination, are classified as epigeal (cotyledons aboveground, usually green and capable of photosynthesis) and hypogeal (cotyledons belowground). Particularly in the monocots, special absorbing organs may develop that mobilize the reserve materials and withdraw them from the endosperm; e.g., in grasses, the cotyledon has been modified into an enzyme-secreting scutellum (“shield”) between embryo and endosperm.

seed

Thank you for signing up!

The nature of seeds

Angiosperm seeds