Categories
BLOG

parts of a plant seed

Parts of a plant seed

Herbaceous:
Plants with stems that are usually soft and bendable. Herbaceous stems die back to the ground every year.

Woody:
Plants with stems, such as tree trunks, that are hard and do not bend easily. Woody stems usually don’t die back to the ground each year.

Photosynthesis:
A process by which a plant produces its food using energy from sunlight, carbon dioxide from the air, and water and nutrients from the soil.

Pollination:
The movement of pollen from one plant to another. Pollination is necessary for seeds to form in flowering plants.

What’s the difference between a fruit and a vegetable?
A fruit is what a flower becomes after it is pollinated. The seeds for the plant are inside the fruit.

Vegetables are other plant parts. Carrots are roots. Asparagus stalks are stems. Lettuce is leaves.

Foods we often call vegetables when cooking are really fruits because they contain seeds inside.

Play a Plant Parts Game!

What Do Different Plant Parts Do?

P lant parts do different things for the plant.

Roots

Roots act like straws absorbing water and minerals from the soil. Tiny root hairs stick out of the root, helping in the absorption. Roots help to anchor the plant in the soil so it does not fall over. Roots also store extra food for future use.

Stems

Stems do many things. They support the plant. They act like the plant’s plumbing system, conducting water and nutrients from the roots and food in the form of glucose from the leaves to other plant parts. Stems can be herbaceous like the bendable stem of a daisy or woody like the trunk of an oak tree.

A celery stalk, the part of celery that we eat, is a special part of the leaf structure called a petiole. A petiole is a small stalk attaching the leaf blade of a plant to the stem. In celery, the petiole serves many of the same functions as a stem. It’s easy to see the “pipes” that conduct water and nutrients in a stalk of celery. Here the “pipes” are dyed red so you can easily see them.

Leaves

Most plants’ food is made in their leaves. Leaves are designed to capture sunlight which the plant uses to make food through a process called photosynthesis.

Flowers

Flowers are the reproductive part of most plants. Flowers contain pollen and tiny eggs called ovules. After pollination of the flower and fertilization of the ovule, the ovule develops into a fruit.

Fruit

Fruit provides a covering for seeds. Fruit can be fleshy like an apple or hard like a nut.

Seeds

Seeds contain new plants. Seeds form in fruit.

Parts of a plant seed Herbaceous: Plants with stems that are usually soft and bendable. Herbaceous stems die back to the ground every year. Woody: Plants with stems, such as tree trunks,

Parts of a plant seed

Our editors will review what you’ve submitted and determine whether to revise the article.

  • University of California Museum of Paleontology – Seed plants: Fossil Record
  • UNESCO World Heritage Centre – Bordeaux, France
  • seed – Children’s Encyclopedia (Ages 8-11)
  • seed – Student Encyclopedia (Ages 11 and up)

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.

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

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.

Seed, the characteristic reproductive body of both angiosperms and gymnosperms. Essentially, a seed consists of a miniature undeveloped plant (the embryo), which, alone or in the company of stored food, is surrounded by a protective coat. Learn more about seed characteristics, dispersal, and germination.