Parts of the seed and its functions

The seed consists of different parts, where each specialized in a function. These are the main parts of the seeds and their functions:

Embryo

The embryo is the new plant contained in the seed. It is very small and is in a state of lethargy. In turn it is composed of:

• Radicle: It constitutes the first rudimentary root in the embryo. From the radicle, secondary roots and hairs are formed that improve the absorption of nutrients.
• Plumule: It is the yolk located on the side opposite to the radicle.
• Hypocotil: This structure represents the space between the radicle and the plúmula. Subsequently with the germination of the seeds this part will become the stem of the plant.
• Cotyledon: This structure will form the first or the first two leaves of the plant. The number of cotyledons of a seed is a method of classification of a plant. Thus, they are divided into monocotyledons and dicotyledons. Learn more in this other post about what a cotyledon is.

Endosperm

The endosperm constitutes the food reserve of a seed, it is usually starch. It is also called Albumen.

Episperm

The episperm is an outer layer and protects the seed seed. In gymnosperms it consists of a layer called Testa, while in Angiosperms are two, with a layer called Tegumen below the Testa.

Deck

Also called tegument, wrap or shell and it is a layer that wraps and protects the central part of the seed and allows it to exchange water with the external environment.

Micropyl

It is a part of great importance in the fertilization of the seed and allows water to enter the seed during germination.

The Seed germination It takes place when the conditions are the most appropriate to ensure the survival of the future plant. Therefore the seed will remain in this state of lethargy until the germination process begins. For this process the most important is temperature and humiditynot being necessary.

In germination, first the radicle that will be introduced into the earth and will continue to develop until it leads to The roots. Its cotyledons will open and the hypocotyl from underneath will begin to develop to give rise to the stem. In the end, The cotyledons They wilt and the stem will begin to sprout The new leaves. In hypogea germination, cotyledons remain below the earth, while in the epigea they remain above.

The Seed classification It can be done according to several criteria:

According to its origin

When classifying the seeds according to their origin, we can divide them into:

• Angiosperms seeds: They come from angiosperm plants, that is, plants with flowers that have seeds inside fruits.
• Gymnosperms seed: They originate in gymnosperms plants. These are seeds that are not found inside fruits, they can be in cones or pineapples.

According to the situation of your reserve substances

Plant seeds have a number of reserve substances and differ in the places where it is stored:

• Endless seeds: In these seeds reserve substances are found in the endosperm. These seeds are usually ideal for germination and are also very consumed or used for the elaboration of various products.
• Exendless seeds: The endosperm of this type of seeds has been totally absorbed by the embryo and reserve substances are stored in an embryo structure.
• Perispermaded seeds: Reserve substances are stored in a fabric called perisperm. These plants also have endosperm, but in a remarkably lower amount, so they receive the help of this.

According to the number of cotyledons

In this case, the seeds can be monocotyledonous if they have a single cotyledon or dicotyledonous, if they have two. According to its conservation

In this case they are classified into orthodox seeds, when they are of great durability and resistance to different conditions. On the contrary, recalcitrant seeds do not have great durability or resistance to conditions, so the ideal is to sow them after obtaining them.

According to its fruits

In this case they are classified according to the fruit they will give rise, although it is a very nonspecific classification. Thus, we have grain seeds, pseudocereales or legumes.

According to the different classification criteria, some of the Examples of seeds with seeds are:

• Grain seeds: For example, oatmeal or rice seeds.
• Pseudocereal seeds: An example is amaranth seed.
• Legume seeds: lentil, alfalfa or beans seeds.
• Angiospermas seeds: apple, avocado or tomato seeds.
• Gymnosperms seeds: pine, fir or cypress seeds.
• Endless seeds: wheat, barley or corn seeds.
• Exospermaded seeds: peanut or walnut seeds.
• Perispermaded seeds: beet or pepper seeds.

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