Bean plants. Plants of the legume family. Fruits of legumes
All adults and even children know beans and peas, beans and lentils, fragrant acacias and clover, peanuts and mimosa, and meanwhile, all of these are plants of the legume (or moth) family. An extensive group, which overestimate the benefits for a person is difficult. We eat these plants, plant for beauty, improve the soil with their help, use wood, paint clothes and even treat ourselves.
Bean family: general characteristics
The family familiar to everyone since school unites a huge number of species, according to approximate estimates, about 17-18 thousand. Botanists divide it into three subfamilies (based on the structure of the flower): cesalpinia, mimosa, moth. It is interesting to note that leguminous plants include the genus Astragalus, the largest in number of species among the flowering species (about 2400). Plants of this family have a fairly large area of growth both in hot tropics (mainly cesalpin and mimosa), and in the regions of the Far North, in deserts and savannas.
Such high adaptability to environmental conditions and climate has provided legumes with almost all life forms existing in the plant world (with the exception of parasites and epiphytes), from huge 80-meter trees to tiny grasses.
Nitrogen fixation is the hallmark of the whole family. The roots of leguminous plants have nodules, which are formed as a result of the growth of parenchymal tissue. And this, in turn, is explained by the introduction and settling inside the plant of nitrogen-fixing bacteria belonging to the genus Rizobium. They have an amazing ability to absorb and accumulate atmospheric nitrogen, which the plant itself further uses for its growth. Such large stocks of a vital element also have a good influence on the environment. Legumes perfectly improve soil fertility. It is widely used both on an industrial scale and by competent and knowledgeable gardeners, who do not forget to alternate the planting of different crops in their area. Every year they return about 100-140 kilograms of nitrogen per hectare to the soil.
The structure of the leaves of legumes
Legumes can have different leaf shapes. They can be divided into several groups:
- paired peristosyllabic and twice peristosyllabic (peas, yellow acacia) leaves, they are located on both sides of the stem;
- simplified (reduced to one apical leaf);
- falsely simple, formed as a result of the accretion of two apical leaves;
- Phyllodia (in African species of acacias) - flattened leaf stalks.
For leguminous plants, an amazing property is characteristic - parotid leaves can fold overnight. This is due to the fact that at the base of the petioles there are nodules that, due to a change in turgor, cause the leaf plate or only the leaflets to move. For example, a shy mimosa is able to do this instantly, since even a light touch of its leaves causes an instant loss of osmotic pressure in them. This property was noticed a long time ago and served as a reason to call it a plant.
Flower and inflorescence
Legumes can have various inflorescences, but most often they are a panicle or a brush, sometimes capitate brushes (clover), much less often they are reduced to a single flower.For members of the family, cross-pollination is typical, in which pollen from one flower is transferred to another much less frequently by insects (bees, bumblebees) or bats and birds in tropical species.
The flowers of leguminous plants can be zygomorphic or actinomorphic (for example, in mimosa). The calyx usually consists of four, less often of five sepals, which grow together. There are 5 petals (for all moths and some representatives of two other subfamilies) or 4. Their name and division are very interesting, depending on the function being performed. So, the most top and large received the name "flag", it attracts the insects pollinating a plant. Petals located on the sides, called wings, and this is a kind of "landing area." The innermost ones, as a rule, grow together with each other along the bottom edge and form a boat that protects the stamens and pistil from insects that are not pollinators. And here, for example, in the Mimosa, all the petals of the same shape are free or fused.
Fruits of legumes
In this case, there is an absolute unity of all types of families.The fruit is called a bob (single or multi-seeded) that breaks through the dorsal or abdominal suture. The seeds inside the fruit are rather large, with or without endosperm, the cotyledons are well developed. The appearance of the bean can be absolutely any, as well as the size. In some species, its length reaches one and a half meters. Seed propagation sometimes occurs on its own, when the sash of the fruit during the opening is twisted in a spiral, and they fly apart in different directions, for example, in acacia. Some tropical species are spread by animals or birds. The ovary of the familiar groundnut (peanut) due to negative geotropism, that is, the ability to grow and develop in a certain direction, when formed, goes into the soil by 8-10 cm, where then the fruit develops.
The value of legumes in the economy
Plants of the legume family occupy the second place after cereal in practical importance for humans. Among them are a huge number of food crops of global importance: soybeans, peas, beans, peanuts, chickpeas, lentils, and many others. Some of them are cultivating is not the first millennium.
Bean plants are of great importance as fodder grasses; this category includes: clover, alfalfa, lupine, sainfoin, etc.Some tropical members of the family (for example, the log wood, pericopsis, dalbergia) are a source of valuable and highly ornamental wood, painted in pink, almost red, dark brown or almost black.
Decorative and medicinal value
There are also ornamental species among legumes, such as wisteria. This tree species comes from China with large wreath fragrant inflorescences. Very popular garden and park plant. Another representative is the whitened acacia, which is widely distributed on the Black Sea coast. From grassy gardens grow, for example, sweet peas, lupins. Everyone knows the color of indigo, but few know that the dye is obtained from a plant of indigofer dyeing, a small shrub from the legume family, with the same name.
Some species have long been used in medicine: fenugreek, astragalus, clover, etc. Everyone is familiar with licorice, or licorice. This is a herbaceous legume plant, which is widely used throughout the world as a cough medicine (healing properties have been known since the times of Ancient Egypt). Its roots and rhizomes are used for this.In some European countries, licorice sweets are very popular, even children love it. They have a characteristic black glossy color.