The gynoecium It is the female reproductive organ of the flower, composed of the set of carpels in phanerogamic plants. The carpel is the floral whorl specialized in the production of female gametes or ovules.
In this regard, carpels are a group of megasporophils or fertile leaves that carry longitudinally folded megasporangia. In the internal part it develops one or more macrosporangia or seminal primordia that will eventually give rise to the ovule.
In gymnosperms the free and open carpels support the ovule without any specialized structure. In fact, they lack an ovarian cavity; without differentiation between styles and stigmata, the ovules are displayed without any protection.
In the case of angiosperms, the gynoecium is made up of a group of carpelar leaves that fuse in the form of a cavity. This structure, called the ovary, contains the seminal primordia where the ovules develop.
Article index
The gynoecium is the fourth flower whorl and represents the female reproductive system of the flower. It is generally located in the central part of the flowers, and is surrounded by a group of reproductive units known as carpels or megasporophils..
The fusion by folding of the megasporophils allows the formation of a chamber called the pistil, which consists of the ovary, stigma and style. The ovary is the concavity where the ovules develop, the stigma receives the pollen, and the style allows the union between both structures.
The ovary is the basal part of the gynoecium, it is made up of the carpelar leaves and the ovules are inserted inside it. In this regard, the carpels are modified leaves that cover the ovules or seminal primordia.
The ovoid-shaped ovules of just millimeters are born on the placenta on the inside of the carpels. In this case, the placenta, made up of a highly vascularized tissue, supports the ovules by a peduncle called a funiculus..
The narrow, tubular shaped structure that allows the ovary and stigma to join is called the style. It is the area that the pollen tube runs through on its way from the stigma to the ovule.
Finally, the stigma responsible for collecting pollen is located through specialized structures such as absorbent hairs or sticky surfaces. The stigma presents the ideal conditions for the development of the pollen tube, and thus transport the male gametes from the pollen grain to the ovule.
It is a structure located in the upper part of a carpel, or of several united carpels. It is the part in charge of receiving the pollen grains, for which they have a sticky surface. It can be located directly on the ovary, or attached to it by means of the style.
Tubular structure formed by the folding of a carpel or by the fusion of several carpels. It is in charge of joining the stigma with the ovule and its length can vary from very long to very short, and may even be absent in some species.
It is the basal portion of a single carpel, or of several fused carpels, and it will contain one or more ovules. Pollination will take place inside the ovary and the fertilized ovules will transform into seeds. After pollination, the ovary will grow and transform, to become the fruit, or part of it.
According to its relative location, the ovary can be classified into three different types:
The ovary is located above the flower receptacle, while the remaining whorl components join the receptacle below the ovary. The flowers that present ovaries with this location are called hypogynous (below the gynoecium).
Also called the middle ovary, this is located at the middle level; the perianth and / or the androecium are inserted in the middle of the ovary's length, which is located in an intermediate position. Flowers with a semi-inferior ovary are called perigine (around the gynoecium).
In this case, the ovary is located within the floral receptacle, while the perianth and / or the androecium are located in the upper part of the ovary. The flowers that have this type of ovaries are called epigines (above the gynoecium).
The ovaries can also be classified based on the number of carpels that constitute them, in that case we will have ovaries of the following type:
The ovary is made up of a single carpel that folds back on itself to close. For example, beans, peas, and beans are single-skinned.
In this case, two carpels fuse to give rise to a single ovary, for example in belladonna and potato.
Also called pluricarpel, similar to the previous case, the ovary is formed by fusion of carpels, but in this case more than two of them are involved. Malvaceae, in general, have this type of ovaries.
Finally, each ovary can have one or more ovules inside. In this case, the ovaries will be classified following an order similar to that indicated above, into uniovular, biovular or multiovular. Examples of each of these cases would be the turkey tail, casuarina and beans, respectively..
As mentioned before, the gynoecium is the female reproductive structure of flowering plants. Its function is related to the production of female sexual gametes, their protection, facilitating pollination, protecting the seeds once they are formed and in many cases, helping their dispersal..
Its function is to receive the pollen grains for the fertilization of the ovules, and to facilitate this the stigma has an adherent surface for the pollen.
It communicates the stigma with the ovary and its function is to allow the passage of the pollen tube. When the pollen grain adheres to the stigma, it germinates to produce a pollen tube, which will grow through the style until it reaches the ovary..
The ovary will contain one or more ovules to be fertilized by pollen. When the pollen tube enters the ovary, it will produce sperm cells that will fertilize the eggs..
When fertilization occurs, the ovum will turn into a seed. Additionally, the pollen tube can produce other sperm cells that will fuse with two polar nuclei located in the center of the embryo sac, coming from the female gametophyte to form a structure called the endospermic nucleus or endosperm..
The endospermic nucleus has the particularity that it is triploid and its function is to divide by mitosis to produce food that will be used by the developing embryo. This process is called double fertilization and is characteristic of flowering plants..
After fertilization, the ovum will grow and develop to produce the fruit, or part of it. The main function of this fruit will be to help in the dispersal of the seeds to new areas. For this, the fruits can be fleshy and have a pleasant taste to attract animals that will eat them and disperse the seed directly or through the feces..
In other cases, the fruits may present structures that allow them to adhere to the animals and thus facilitate the dispersal of the seeds, or they may also present structures that facilitate aerial dispersal..
In botany, the ovaries are the structure of the gynoecium that forms the seminal cavity that contains the mature ovules for fertilization. The classifications are diverse based on the position, number of carpels or number of ovules that allows classifying the types of ovaries.
According to the position of the ovary, in relation to the different parts of the flower, the following classification is obtained:
Based on the number of constitutive carpels, the ovaries can be classified into:
Regarding the number of ovules present in each ovary, they can be classified into:
Placentation is related to the arrangement of the seminal primordia that will give rise to the ovules on the ovary. That is, the position of the attachment points of the ovules on the placenta in the ovary.
The placenta is the internal tissue of the ovary where the leaf primordia join. The arrangement and number of placentas is subject to the number of carpels that constitute the ovary.
Placentation occurs in different forms, the most common being:
Yet No Comments