Each organ of a plant has its own structural features, which fully correspond to the functions performed. So, the leaf provides photosynthesis, and the root - soil nutrition. The generative organ is a flower, from which a fruit with seeds is formed. In our article, we will consider the features of their physiology and role in plant life.
What is an organ
An organ can only be called 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 the rhizoids of algae only in appearance resemble underground organs. In fact, they consist of a collection of individual cells that are connected only anatomically. Therefore, such a structure cannot be considered an organ.
Let's consider the structure of higher angiosperms. Their underground organ, as already mentioned, is the root. On the surface is an escape. It consists of an axial part - a stem, and a lateral part - a leaf. In the process of growth, a flower is formed on the shoot, from which the fruit develops.
Types of plant organs
OrgansPlants are classified according to different characteristics. According to the functions performed, vegetative and generative are distinguished. The first group includes root and shoot. First of all, they carry out vegetative reproduction, which is possible due to the splitting off of a multicellular part from the whole organism. It can be carried out by root suckers, tubers, cuttings, leaves, bulbs. Vegetative organs also perform other functions in the plant. These are photosynthesis, soil nutrition, growth, holding water and minerals.
The generative organ is necessary for the plant to carry out sexual reproduction. This type of reproduction of one's own kind has an important advantage. Only during sexual reproduction does the recombination of genetic material occur, as a result of which new, most often useful, traits appear. Due to this, the plant organism has the ability to adapt to new conditions of existence.
Which plant organ 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. In the course of its development, a fruit 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 out into the water and merge in pairs. As a result, a zygote is formed. It is covered with a thick shell and in this state enduresfreezing and drying. When conditions are favorable again, the contents of the zygote divide to form four motile spores.
In higher spore plants, germ cells mature in specialized organs called gametangia. In bryophytes, they are located at the top of the stem and look like oval formations. And in ferns, male and female gametophytes are formed on the same plant - the growth. Eggs and sperm cells 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 distinctive feature 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 pistil, in which the egg is located, and the stamen, which contains sperm. When they merge, the embryo of the future organism is formed.
A shortened and limited in growth modified shoot is called a flower. In addition to the stamen and pistil, it includes a pedicel and perianth. The first part is an elongated continuation of the stem. In nature, shortened and barely noticeable pedicels are often found. Examples of such plants are corn, sunflower, plantain, clover. Such structures are called sessile.
The composition of the perianth includes a calyx, consisting ofaggregates of carpels, and corolla. The latter is formed by petals, which are modified leaves. In many plants, the corolla is large and bright. Roses, tulips, chrysanthemums, lilies - all these flowers have long been a wonderful decoration for any holiday precisely because of this sign. These flowers attract insects. Wind pollinated plants have nondescript corollas and form inflorescences.
The essence of double fertilization
The process of gamete fusion is preceded by pollination. This is the transfer of pollen from the anther of the stamen to the stigma of the pistil. It is carried out with the help of wind, insects, water or a person. During fertilization, two sperm are involved. Descending with the help of the germ tube into the ovary of the pistil, 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 is formed - the fetus. 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, grain and nut are dry fruits.
Seed and its biological significance
The seed is also referred to the generative organ of a flowering plant. This unique structure first appears in conifers. At this stage, the seed plants occupydominant position on the planet. The thing is that, compared with seed, they have more progressive structural features. First of all, this is the presence of reserve nutrients and seed coats, which reliably protect the embryo from moisture and temperature differences provided by the pericarp.
So, the generative organ of angiosperms is a flower, as a result of which fruits and seeds are formed. These structures provide the process of sexual reproduction of plants and the emergence of new progressive structural features of organisms.
