What is a stalk? From the point of view of biology, this is the part of the plant on which the leaves and flowers are located, which is a continuation of the vascular system, originating in the roots. The main function of the stem is the delivery of water and the necessary minerals from the soil to the leaves and other parts of the plant. Green stems are also responsible for nutrition and are involved in photosynthesis.
Stem: its structure and significance
Tissues at the end of the stem, capable of cell division and causing its elongation, are called apical meristems. The layers of the stem include the epidermis - this is the outer layer of cells coated with special plant wax, which provides protection from the external environment. Primary tissues bind the epidermis and internal phloem, which are responsible for the distribution of photosynthesis products throughout the plant. Xylem tissues distribute water and minerals from the roots to the very top, thus providing structural support in plants. Cambium tissues are a layer of fissile tissues; their growth allows the trunk to grow in width. The value of the stem is, first of all, in providing vital substances to the whole plant. If it is damaged or tightly bandaged, then over time, tissues lacking nutrition begin to dry out slowly. Complete death occurs with the death of the root system. Parts of the stem also include the core, which in old woody plants is filled with the hard xylem of wood fibers and is used to identify plants. It can be solid or hollow. Its cross section may be round, triangular or star-shaped.
External characteristics
What is a stalk and what does it look like? The top of the stem is its main point of growth. Receptors located there can be presented in the form of leafy vegetative buds and reproductive buds. In many plants, the special apical hormone auxin inhibits the development of lateral buds, thereby orienting the plant upward and not to the side. If the apical bud is removed during pruning, then the lateral buds growing from the axils of the leaves will develop more actively, and the stem will take on a bushy shape. As a rule, altered sheets cover the top - renal scales, which serve to protect. The bark is an external protective tissue of woody plants and develops with age.
Vascular system
The vascular system is represented by a network of pipes through which water and nutrients are transported throughout the plant, connecting the roots, stem and leaves. Not all representatives of the flora can boast of this, for example, mosses and algae receive food in a diffuse way. Vascular plants include flowering and coniferous plants, as well as ferns. The system consists of two main tissues: phloem and xylem. Xylem is a network of pipes that transport water and minerals throughout the plant. In addition, it also provides a secondary function - structural support, it can be compared with the spine, which helps to maintain an upright position. The texture of the stem often depends on the amount of this fabric, for example, it is very much contained in tree trunks, its colors are much less.
Common Stalk Varieties
- Woody. These include vertically growing trees with a relatively large core, as well as shrubs (roses, grapes, blackberries, raspberries).
- Modified For example, tulips, lilies and onions have a thickened underground stem with fleshy leaves. The gladiolus has a short, thickened underground stem with shortened scaly leaves. A compressed stem, with leaves and flowers growing above and below the roots, has strawberries, dandelions, and African violets.
- Horizontal For example, overhead shoots of strawberries, iris.
- Curly stems (hops, honeysuckle, beans).
- Types of stems also include tuber, such as potatoes.
- A hilly trunk, short and flattened, is found in begonias and dahlias. Unlike tubers that have scattered receptors, tuberous stems have only leafy buds on top.
Stem functions
1. It supports leaves, flowers and fruits, linking them to the roots. In trees and shrubs, the main stem or trunk is characterized by a strong columnar structure.
2. It is a conductor of water, nutrients and photosynthesis products. Its transport system is arranged in such a way that vertical and lateral movement within the plant organism becomes possible.
3. The ability to retain water and photosynthesis products is a vital function of the stems of plants such as cacti and palm trees.
4. The young green stalk plays a secondary role in food production due to the process of photosynthesis, but in some species (for example, cacti), the stem is the main photosynthetic organ.
5. It serves as a means of asexual reproduction in many plant species, including cuttings.
Stem parts
All stems of angiosperms, including those that are highly altered, have nodes, internodes, buds and leaves. A knot is the point from which leaves or buds grow. The area between them is called the internode. A bud is an embryonic stem that has the potential for growth and development. It can develop into a leaf or flower. Such buds are referred to as leaf buds, buds and mixed buds. Many of them remain at rest for a certain period, then grow into separate parts or integrate naturally into stem tissues and are hardly noticeable. Trees and shrubs, in addition to the main stem, as a rule, also have lateral branches, to which smaller branches are attached. In addition to leaves and buds, other structures may be present in the form of hairs, which are outgrowths of epidermal cells, spines and stipules.
Stem size
When answering a question about what a stalk is, it is important to consider its size as well. In relation to all plants, it is most often the aerial part, which provides structural support and serves as a mediator and conductor between the root system and leaves. The stems vary in size, starting with a small sprout of the vine to a 15-meter-tall tree!
Value
What is a stalk? We can say that this is the central axis to which all other parts are attached. In most plants, they are located above the surface, but in some species the stem may be hidden underground. Its structure and meaning are inextricably linked. Due to its unique structure, water and nutrients are delivered both to the leaves and to the roots. The importance of the stem cannot be overestimated, the overlap of this vital artery leads to the death of the plant. There are a large number of industrial applications, including woodworking (logs, firewood, lumber). It is also a rich source of pulp for making paper; certain types of stems can be a source of nutrition. Its fibers in processed form are part of drugs, latex, tannins, paints and much more. Some types of stems are used for asexual or vegetative propagation of plants.
A huge number of applications
There are thousands of plant species whose stems are of great importance for agriculture, such as potatoes. Sugarcane stalks are the main source of sugar. Maple sugar is obtained from maple trunks. Vegetables use asparagus stalks, bamboo shoots, kohlrabi and water chestnut. Spicy cinnamon is the bark. Gum Arabic is a dietary supplement derived from acacia trunks. Chikle is the main ingredient of chewing gum, extracted from the chikle tree. They make paper, furniture, boats, musical instruments, fishing rods, water pipes from bamboo and even build houses. Cork is obtained from the bark of cork oak. The rattan used for furniture and baskets is made from the stems of a tropical palm tree. The earliest example of the use of this important part of the plant is papyrus, popular in ancient Egypt. Amber is a petrified sap from tree trunks, used for jewelry and may contain the remains of ancient animals. Softwood resins are used for the production of turpentine and rosin.