A flower is one of the most aesthetically attractive parts of a plant. But in nature, he has a completely different role. In our article, we will consider a diagram of the structure of a flower and its relationship with the functions performed.
Generative organs
Depending on the functions performed, all parts of the plant are combined into two groups: vegetative and generative. The first include root and shoot. They provide growth, mineral and organic nutrition, as well as vegetative propagation of plants.
Generative organs are a flower, a seed and a fruit. They provide sexual reproduction, distribution and distribution of plant organisms. The flower is a shortened and limited in growth, modified shoot. It can develop at the apex of the shoot or in the axils of leaves from generative buds.
For children, the structure of the flower is usually depicted in the form of petals on the peduncle. In fact, its structure is more complex.
Flower: structure scheme
The structure of the flower can be schematically represented as follows:
1. The sterile part
- peduncle;
- receptacle;
- cup;
- whisk.
2. The fertile part
- pestle (gynoecium);
- stamen (androecium).
Stem part
In most plants, flowers are attached to the shoot with a peduncle. It is an elongated continuation of the stem. If the stalks are shortened and visually invisible, such flowers are called sessile. Examples of such plants are corn, clover, plantain.
The upper expanded part of the peduncle is called the receptacle. This is the base to which the cup, corolla, pestle and stamens are attached. Depending on the form, several types of receptacle are distinguished. For example, it is concave in plums, and elongated in blackberries. Peony has a flat receptacle, raspberries and buttercups - convex.
What is perianth
This part of the flower is represented by a cup and a whisk. The first consists of modified leaves. Most often they are painted green. Sepals play a particularly important role in a period when the flower has not yet opened. They protect the bud from mechanical damage. Since the sepals contain chlorophyll, they carry out photosynthesis and additionally supply the plant with organic substances.
Nettle, beetroot and raven eye have a calyx perianth. This means that their petals are colored green. Rose, tulip, chrysanthemum - examples of plants with corolla perianth. Their petals are brightly colored, which attracts pollinating insects.
In cabbage and radish, the cup is dioecious. This means that it consists of sepals, which do not grow together with each other. Potatoes and rosehips have a lily cup.
A whisk is the combination of another type of altered leaves - petals. They usually have a bright color, which attracts insect pollinators. The corolla, like a cup, can be separate - or interconnected.
Using the example of the structure of the lily flower, we can consider the structure of a simple perianth. It consists of only six free or partially fused petals. Sepals are absent. The structure of the tulip flower is similar to a lily. Its petals do not grow together, in a checkerboard pattern attached to the receptacle with their base.
In nature, there are species devoid of perianth. For example, willow and ash. They are called naked. Such flowers are pollinated by the wind.
Diagram of the structure of a bisexual flower
The fertile part is represented by stamens and pestles. Depending on its structure, two types of flowers are distinguished. Same-sex can be either pistillate or staminate. They are also, respectively, called male or female. But the structure of the cherry flower is an example of a bisexual flower. It has both stamens and pistils.
If unisexual flowers are located on the same individual, such plant species are called monoecious. Their examples are corn, cucumber, oak, pumpkin. In sea buckthorn, willow and poplar, male and female flowers develop on different individuals. Such plants are called dioecious. Consider the structure of the fertile part in more detail.
Androecium
Stamens are the male part of the flower. They are located in one or more circles around the inner edge of the perianth. Each of them consists of a stamen filament and anther in which male germ cells are formed - sperm. They are called pollen.
The structure diagrams of flowers of various species illustrate that the number of stamens in can vary from one to several hundred. Sperm are motionless cells. Therefore, the process of fusion of gametes is preceded by pollination. This is the transfer of pollen from the anther of the stamens on the stigma of the pestle. It occurs with the help of wind, insects, water or humans.
Gynoecium
The number of pistils in a flower may also vary. For example, in a tulip and an apple tree, he is alone. But buttercup and strawberries have several dozen pistils.
Each such structure consists of three parts: ovary, column and stigma. The first is the lower expanded base of the pestle. Here is a female gamete - an egg. The ovary crosses an elongated tube called a column. And on top of the pestle a small expansion forms. It is called the stigma.
A pestle is formed by one or more carpels, which are modified leaflets. Ovaries are located on the inner walls of the ovary. Their integument does not grow together, as a result of which a hole is formed - a pollen pass. After pollination and fertilization, seeds develop from the ovules, and the pericarp develops from the walls of the ovary.
Double fertilization of flowering plants
The structure of the flower provides the function of sexual reproduction. The ovum is located in the embryo sac, and sperm are in the pollen grains. Getting on the stigma of a pestle, pollen sprouts a pollen tube. It enters the embryo sac through a special hole. It is called a dust collector. Through a tube with a current of cytoplasm, two sperm from pollen grain penetrate into the embryo sac. After this, fertilization occurs - the process of germination of germ cells.
One sperm merges with the egg, the second - with the central germinal. Therefore, this process is called double fertilization. A fertilized egg is called a zygote. Over time, an embryo develops from it. The fertilized central germ cell gives rise to the endosperm. These are the nutrients that are necessary for the development of the embryo.
Outside, the embryo and endosperm are peeled. And in the aggregate, all these structures form a seed. Depending on the number of cotyledons, flowering plants are combined in two classes: monocotyledonous and dicotyledonous.
So, a flower as a generative organ consists of fertile and sterile parts. Its main structures are the stamens and pistils, in which the germ cells are located.