What is plant fertilization? Gymnosperms and angiosperms
Due to our nature, it is simple for us to imagine how animals reproduce because their fertilization process is usually similar to ours. However, finding similarities with the plant world takes a little longer. How do they do it? What is plant fertilization?
The aim of the article is to explain what fertilizing plants is. For this purpose, we will talk about two vast groups that exist: Angiosperms and gymnosperms. If you are interested in the topic and want to learn more about fertilizing plants, do not hesitate and read on.
Fertilizing plants
Before we explain plant fertilization, let us first comment on what the concept of fertilization is. This is the process by which Two gametes, male and female, fuse during reproduction. This creates a zygote that contains the genome, the product of the parents.
In the world of plants, First comes pollination. The male reproductive leaves produce pollen grains that are carried by insects or wind onto the stigmas. This is where they germinate. When we talk about plants, we usually do not mean gametes, but spores. Each pollen grain usually contains two male reproductive cells, or gametes. However, there are different methods that plants exploit because not all species are the same, in fact they differ slightly when it comes to reproduction.
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As you well know, plants can be differentiated in many ways. There are a vast number of groups, classes and types of vegetables, and each species belongs to several. However, there are two vast groups that differ in their method of reproduction. To, There are vegetables with flowers and those without flowers. The former are known as angiosperms and are the most ample plants on this planet. Moreover, these two types of vegetables are the newest. On the other hand, flowerless plants belong to the group of gymnosperms. They were the first to appear on Earth, before the dinosaurs.
Angiosperms include various plants such as shrubs, trees, azaleas, dimorphotheca, etc. As for gymnosperms, they mainly consist of conifers. Examples of this group include cedars, yews and pines. Cycads are also gymnosperms. But don’t worry, we will talk in more detail about both types of plants, their structure and how to fertilize them.
Gymnosperms
Let’s start with gymnosperms. While it is true that these plants are known for not having flowers, they do but not as typical as we imagine. Its flowers have no sepals or petals, but the female flowers form a type of woody and greenish cones that eventually become false fruits like cones.
Plants in this group have both male and female flowers. The latter has a scale, two ovules and a bract that form a female cone, grouping around the axis of the flower. Each egg cell contains an embryo sac containing two archegonia. which in turn have two female gametes or oospheres. Let’s explain these concepts:
- Archegonia: It is the female reproductive organ. fungi, seaweeds and bryophytes such as mosses and some vascular plants such as ferns. It is completed by a male organ called the antheridium.
- Oospheres: It is the female gamete of plants. They come from a so-called megaspore in a process called megagametogenesis. At a basic level, we can say that it consists of mitotic divisions. During double fertilization, the oospheres fuse with the generative nuclei of the pollen grain, thus giving rise to the embryo.
As for the male flowers, they form male cones around the flower axis. They have a scale, as well as two microsporangia or pollen sacs, in which they form mother cells, from which the renowned pollen grains are created. Inside them there are a total of two male gametes, also called antherosoids. They also contain two air sacs that facilitate them spread until they reach the female flower. In this case, I think it would be good to also clarify a few concepts:
- Microsporangia: These are structures that produce and contain spores. These are basically microscopic bodies whose purpose is to disperse and survive for a long time.
- Anterozoids: Basically, it is the male gamete, which would be the equivalent of our sperm.
Fertilizing gymnosperms
Knowing a little about the structure of male and female gymnosperm flowers, we will now comment on how this fertilization works. It should be noted that pollen grains can take up to a year to germinate after reaching the female flower. When this happens, the pollen tube opens very slowly through the so-called nucleus of the ovule. Once it reaches the female gametophyte, its next task is to pass through the neck of the archegonium and then enter the oosphere. where you can download all your content. At this time, fertilization of gymnosperms occurs.
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Angiosperms and gymnosperms
During this process, one of the gametes fuses with the nucleus of the oosphere, where it occurs. As a result, a zygote is formed, i.e. a cell from which an embryo is formed and develops. As for the vegetative nucleus, all other archegonium cells and the second male gamete degenerate. Meanwhile, an endosperm composed of reserve cells surrounds the embryo, which is protected by the ovule integument, which in turn becomes lignified. The embryo is considered fully mature when the seed is released. This process can easily take two years from the time the flowers appear.
In the case of pine seeds, the seed coat is diploid and produced by the maternal sporophyte. As for the primary endosperm or reserve tissue, it is haploid because it is part of the female gametophyte. After fertilization, a diploid embryo is formed, which is a recent sporophyte.
Angiosperms
We already know what gymnosperms are and how they work, but what about angiosperms? Before I explain how to fertilize these plants, First we need to clarify some concepts To better understand the process:
- Bars: These are modified leaves that entirely form the female reproductive part of the flower of angiosperms. The set of all pistils in a flower is called the gynoecium.
- Stigma: It is this part of the gynecologist that receives pollen during pollination.
- Micro dust: Also known as a micropyle, it is a hole or opening located in the apical part of the seed bases or ovules.
- Synergists: These are cells with a nucleus located at the end of the embryo sac of angiosperms. There are two of them in each embryo sac. Both synergids together form a filiform or pillar apparatus. It is worth noting that they facilitate the oosphere during the fertilization process.
- polar nuclei: These nuclei are cells found in the embryo sac, female gametophyte, or ovary. They interfere with the fertilization of vegetables.
It should be said that each embryo sac has different types of cells, including the fertile ones are the polar nuclei and the ovule. However, the sterile ones, i.e. antipodal and synergistic ones, also cooperate in the fertilization process.
fertilization of angiosperms
At the end of the topic of fertilization in plants, we will talk about the functioning of angiosperms. After pollination of the pistil, a sweet fluid, consisting mainly of sucrose and produced by the mature stigma, stimulates the germination of pollen grains. From each of these grains emerges a pollen tube whose purpose is to create a path through the style until it reaches the female gametophyte or embryo sac of angiosperms. This embryo sac is located inside the embryo.
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The male gametes or generative nuclei move through the pollen tube until they reach the micropyle. The pollen tube passes through this structure and throws all its contents into the embryo sac, near one of the two synergids. After this process, the generative nuclei fuse with both the oosphere and the polar nuclei, which is why it is called “double fertilization”.
There are many pollen grains that usually reach the stigma and consequently germinate. However, only one of them will cause fertilization. After fertilization, the ovary begins to grow into a fruit. Fruits that have several seeds also contain several pollen grains necessary to attach to each ovule.
It’s entertaining how nature has arranged everything so that different types of vegetables can breed, right? Without a doubt, this land is full of amazing imaginative and breeding abilities.