Each organ of the plant has its own structural features that are fully consistent with the functions performed. So, the leaf provides photosynthesis, and the root - soil nutrition. The generative organ is the flower from which the fruit is formed with seeds. In our article we will consider the features of their physiology and the role in plant life.
What is an organ?
An organ can be called only a structural unit of a plant, which is formed by several types of tissues. For example, the root consists of conductive, mechanical, educational and integumentary varieties. But rhizoids of algae only in appearance resemble underground organs. In fact, they consist of a collection of individual cells connected only anatomically. Therefore, such a structure cannot be considered an authority.
Consider the structure of higher angiosperms. Their underground organ, as already mentioned, is the root. On the surface is an escape. It consists of the axial part - the stem, and the side - the leaf. In the process of growth, a flower is formed on the shoot, from which the fruit develops.
Types of plant organs
Plant organs are classified according to various characteristics. The functions performed are distinguished between vegetative and generative. The first group includes root and shoot. First of all, they carry out vegetative propagation, which is possible due to the splitting off of the multicellular part from the whole organism. It can be carried out by root offspring, tubers, cuttings, leaves, bulbs. Vegetative organs perform other functions in the plant. This is photosynthesis, soil nutrition, growth, water and minerals.
The generative organ is necessary for the plant to carry out sexual reproduction. This type of reproduction of their own kind has an important advantage. Only during the course of sexual reproduction does the recombination of genetic material occur, as a result of which new, most often useful, signs appear. Due to this, the plant organism has the ability to adapt to new conditions of existence.
Which organ of the plant is generative
Gametes take part in the process of sexual reproduction. These specialized cells are located in organs, which are called generative. In a plant, it is a flower. During its development, a fetus is formed in which the seeds ripen. Not all plants capable of sexual reproduction have such a generative organ. For example, unicellular algae under adverse conditions are able to form gametes. They go into the water and merge in pairs. The result is a zygote. It is covered with a thick shell and in this state tolerates freezing and drying. When favorable conditions reappear, the contents of the zygote divide with the formation of four motile spores.
In higher spore plants, germ cells mature in specialized organs called gametangias. In bryophytes, they are located on the top of the stem and have the form of oval formations. And in ferns, male and female gametophytes are formed on the same plant - a sprout. The eggs and sperm mature at different times, so the process of their fusion occurs between different plants. All spore plants need water for fertilization. This feature is a hallmark of this systematic unit, which they "inherited" from algae.
Flower structure
The generative organ of seed plants, which is represented by a flower, has the most perfect structure. Its main parts are the pestle, in which the egg is located, and the stamen containing sperm. When they merge, the embryo of the future organism is formed.
A flower is called a shortened and limited in growth, a modified shoot. In addition to the stamens and pestle, it includes the peduncle and perianth. The first part is an elongated extension of the stem. In nature, shortened and barely noticeable pedicels are often found. Examples of such plants are corn, sunflower, plantain, clover. Similar structures are called sessile.
The composition of the perianth includes a cup, consisting of a set of carpels, and a corolla. The latter is formed by petals, which are mutated leaves. In many plants, the corolla is large and bright. Roses, tulips, chrysanthemums, lilies - all these flowers have long been a wonderful decoration of any holiday precisely because of this symptom. Such flowers attract insects. Wind-pollinated plants have inconspicuous corollas and form inflorescences.
The essence of double fertilization
The process of merging gametes is preceded by pollination. This is the process of transferring pollen from the anther of the stamen to the stigma of the pestle. It is carried out with the help of wind, insects, water or humans. Two sperm take part in the course of fertilization. Sinking with the germ tube into the ovary of the pestle, one of them merges with the egg, and the other with the central germ. Therefore, this process in flowering plants is called double.
Fruit types
As a result of the fusion of gametes, a modified generative organ, the fetus, is formed. It consists of a seed surrounded by shells. They are called pericarp. It can be dry and juicy. Examples of the first group are apple, drupe, berry, and pumpkin. But the bean, pod, box, achene, grains and nuts are dry fruits.
Seed and its biological significance
Seed is also referred to the generative organ of the flowering plant. This unique structure first appears in conifers. At this stage, seed plants dominate the planet. The thing is that, compared with seed, they have more progressive structural features. This is primarily the presence of reserve nutrients and seed shells that reliably protect the embryo from moisture and the temperature difference provided by the pericarp.
So, a flower is the generative organ of angiosperms, as a result of the development of which fruits and seeds are formed. These structures provide the process of sexual reproduction of plants and the emergence of new progressive features of the structure of organisms.