Very often there are trees or herbaceous plants with voluminous trunks and stems. Why do trees grow in breadth? What is cambium, read the article.
Cambium
What is cambium? This is a very thin layer of educational tissue, that is, living cells that are able to divide and grow in thickness. The result of these processes is the formation of wood and bast cells . In the process of development, the cambium lays bast cells outside, and the wood cells inside. It is located under the bark.
What is cambium and where is it located? These are cells of educational tissue. In the layer are located one above the other, and in relation to the trunk - between the wood and the bark. In a temperate climate, the cambium freezes in the winter, and in the spring, its activity resumes. First he awakens in the young parts of the tree, and then in the old.
Cambium cell structure
What is cambium, and what is the structure of its cell? It has a small size, elongated tetrahedral shape. The ends of the cells are beveled. The length can be different: in dicotyledonous plants - half a millimeter, in gymnosperms - three and a half millimeters. The cell is densely filled with granular plasma with a fusiform nucleus in the center. Sometimes it contains starch. The shell is not woody, soft and very elastic. But for the winter its walls thicken. Cells with this description form from one to three layers, but only one layer is considered a real cambium.
How is cambium formed?
It consists of mother cells: longitudinal, reaching several millimeters in length and having beveled ends, and short radiation, which are grouped in the rays of the core and pass through the cambium.
What is cambium and how many layers of cells does it contain? Cambium has only one layer of cells, which is plate cells of one of the rows of the cambial zone. These cells are very similar to cells of other layers, so it is impossible to distinguish them. However, cambium-forming cells are significantly different in that they are able to re-divide under favorable weather conditions.
The result of regulated processes of tree development is the sequential formation of other cells for various purposes by cambium cells. This is a very subtle organization. Neighboring cells must exchange among themselves, because they produce new cells of their type at a certain time. The cambium lives while the tree is alive.
By multiplying, the cambium cell is divided in half. One cell is thin-walled, it is located on the outside of the trunk, the other is woody, with thick walls, sent to the core. Cambium forms broad cells with a thin membrane in the spring. Therefore, the wood of this season is called spring. In the vegetative period, when leaves and shoots develop, flattened cells with thick walls are formed by the cambium. The wood formed at this time is called summer. During the vegetative period, annual layers are formed, by which you can determine the age of the tree.
The structure of the inner part of the stem
Herb plants and trees have a different structure of this part of the stem. What is cambium in trees? Dicotyledonous plants have an educational tissue called cambium, due to which they grow in thickness. An example is trees such as maple, linden and others. Plants have no monocotyledonous cambium; therefore, their thickness almost does not increase.
Dicotyledonous woody plants form concentric layers: wood, cambium, bast. In the center of the stem is the core, the cells of which perform the function of accumulating nutrients. The cells of the peripheral part of the core are smaller, and their walls are thick.
Wood is located on the outside of the core. Vessels are pathways. Water flows to the leaves along them, and its roots absorb. Together with water, the tree receives all the nutrients. Wood contains fabrics called wood fibers. Due to them, the barrel has strength. The main fabric of wood is parenchyma. She is responsible for replenishing food supplies.
Cambium of monocotyledonous and dicotyledonous plants
What is cambium in plants? The monocotyledonous representatives of the flora have almost none. An existing procambium is transformed into primary conductive tissue. Dicotyledonous plants have the ability to form cambium from procambium, giving rise to conductive secondary tissues. As a result, the formation of the secondary structure of the stem.
What is cambium in plants? See the photo below. Cambium stems of dicotyledonous herbaceous plants have an activity of one vegetative period. As soon as autumn comes, its cells turn into permanent tissue. The cambium of the stems of woody plants has activity all his life until the tree dies. But in winter and autumn, the cambium begins a period of rest.
Dicotyledonous herbaceous plants: stem anatomy
The anatomical structure of these plants is structurally primary and secondary. The formation of the primary structure occurs at an early stage of stem development.
But it is rapidly moving into the secondary stage, since the cambium at this time begins its activity. The secondary structure is characterized by three types: beam, transition and non-beam.
Beam structure of plants
It is characterized by the laying of cambium in separate bunches, which are located in the stems in one row in a circle. The formation of a continuous cambial ring occurs while maintaining the beam structure. This process is preceded by the formation of an inter-beam cambium, which, in conjunction with the primary beam, forms a ring. Sometimes the bundle cambium is weakly expressed, which does not clearly distinguish the primary structure from the secondary.
Non-fluffy plant structure
It is characterized by the fact that, regardless of the primary structure of the stem, under the influence of secondary changes, a plant with the same structure can form: a common cambial ring.
The anatomical structure of the annual stems of tree species and herbaceous plants is similar: the conductive system has a non-beam structure. Their distinguishing feature is the formation of integumentary tissue as a result of the active activity of cambium.
When the cambium begins its work, various elements of secondary origin are formed in the stems, which leads to the gradual disappearance of the primary. What is cambium biology? Translated from the Latin language, this is the exchange of cells in the stems of plants between forehead and wood.
Xylem (wood) and phloem (bast) are not formed equally by cambium in time, as a result of which the xylem share is the mass of branches and trunk, and the phloem fraction is the bark, and its thin layer. Such a distribution of cells occurs because much more wood cells correspond to a single bast cell during distribution. So the cambium ordered.