Fruit. Classification of fruits in botany
In the world of flora, there is a group of plants (about 250 thousand species) capable of fruit development. Their distinctive morphological trait is the presence of a flower. Of all the parts - the ovary, corolla, pedicels, calyx with calyx - in the process of double fertilization, the pericarp with seeds - fruits develop.
Species of angiosperms differ among themselves by many traits, including various types of pericarp. Carpology is a branch of botany that studies the fruits. The classification of fruits is carried out by a section of biology called systematics. In this article, we consider the main criteria used by scientists to determine the pericarp in angiosperms.
Why use knowledge about the structure of the fruit
The description of the type of the pericarp, as well as its external and internal structure, is a necessary condition, without which it is impossible to correctly determine to which family a particular flowering plant belongs.For example, the bean fruit is dry and uncovered. It is characteristic only for plants of the legume family, for example, beans, peanuts, peas, alfalfa. Representatives of the family Cereal belonging to the class Monocotyledonous, have a dry non-opening fruit kernel. That is why wheat, rye, and barley are often called cereals. What is necessary to pay attention to the classification of the fruits of plants was carried out correctly?
Features of the structure of the pericarp
So, only plants with flowers are capable of forming fruits. What is their structure? From above the pericarp is covered with a seed skin - an exocarpium. It is formed from integuments of the seed germ. Next is the middle layer - mesocarp. On its structure, we dwell in more detail. If the cells of the middle layer contain a lot of water with mineral salts and glucose dissolved in it, it becomes fleshy, and the fruits in this case are called succulent, for example, in cherry, plum, peach. The latter, the inner layer of the pericarp, under which the seed lies, has a hard, woody texture and is called the endocarp. The structure of the pericarp is the main criterion by which classification of fresh fruits in biology and agriculture is carried out.
What is the fruit seed
Some plants contain not one, but several pestles at once. After fertilization, the same small fruits are formed, growing together as they mature. So, raspberry and blackberry have complex multi-peasant pericarpia. If in the flower - one pistil (as in cherry, apricot), then simple simple fruits develop. The classification of fruits adopted in botany necessarily takes into account this criterion. The flowers of pineapple or mulberry in inflorescences are located so close to each other that in the process of development small fruits grow together. In figs, not only the flowers themselves, together with the receptacles, but also the axis of the inflorescence take part in the formation of stems. All these examples describe succulent stems, but there are also dry species. For example, in beet flowers, the perianths become rigid and woody, and then they grow together to form dry globular stems consisting of 3-8 small fruits.
As we see, angiosperms have simple and complex fruits. Classification of fruits allows scientists - botanists, along with other morphological features (type of inflorescence, type of root system, shape of leaves and their position on the stem) to correctly determine which family the studied plant belongs to.
Types of juicy fruits
Berry crops such as black and red currants, gooseberries that are widespread in home gardens, have a fleshy pericarp with a well-developed middle layer — the mesocarp. Their fruits are juicy berries. In an apple, quince, and pear tree, a person uses a multi-seeded fruit, an apple, and his flesh develops from an expanded receptacle. Tykvina is another kind of juicy pericarp, but its outer cover does not look like a thin shell, but a hard layer consisting of mechanical tissue — sclerenchyma. In some plants, the pumpkin fruit has a cavity inside, filled with the placenta with seeds (melon, pumpkin). Other members of the Pumpkin family - watermelon, cucumber, zucchini, contain mesocarp, fused with the placenta and seeds. Plants belonging to the same family can have both similar and different in structure, fruits. The classification of fruits takes into account the characteristics of the tissues of which all three shells consist: the skin, the mesocarp, and the endocarp.
Why fruits are called dry
If in the process of ripening the middle layer of the pericarp loses water and grows together with the inner shell, the fruit is called dry.Often for a person of practical interest is to use not the fruits themselves, but only their seeds hidden under the pericarp, for example, in plants such as beans, peas, walnuts. Depending on the structure of the pericarp, there are undifferentiated and open dry fruits. Taking into account the peculiarities of pericarp development, the classification of fruits is carried out in the systematics of plants. Biology applies morphological and histological criteria in determining the type of pericarp, paying attention to the structure of the exo - and mesocarp.
Types of dry fruits
Revealing multi-seeded fruits have plants of the legume family: alfalfa, vetch, peanut, pea. Cabbage, mustard, and colza fruits look like beans, but they are not. Their name is a pod or a pod, as the seeds are not attached to dry sash, but develop on a special partition. Non-swept dry single-seeded fruits are an acorn, a nut, a seed, a kernel. They are found in plants of the Astrovye, Beech, and Cereal families.
In the article, we studied the classification of fruits and vegetables used to study angiosperms.