The structure of plants is very diverse and differs even within the same species. The most ancient representatives of flora, many of which are extinct, did not have clearly differentiated into specialized body organs, they lacked roots, leaves, stems, etc. Among modern vascular plants, the presence of one or another organ reflects the degree of their adaptation, especially in relation to the requirements of the terrestrial-air environment. The main problem here is obtaining water, and in order to solve it, terrestrial plants developed roots. Leaves, roots, stems, flowers, and fruits show considerable variability in size and quantity from taxon to taxon. The shape and structure of these parts are controlled by genes, but some of their characteristics (size, coloration) are quite flexible in their variation.

Vascular plants consist of a root system and a shoot system
The structure of plants is not that complicated, the first thing to remember is that they are divided into a root and a shoot, and already these parts are subdivided into smaller organs. Roots and shoots grow by their ends, on which the apices develop. The root system anchors the plant by penetrating into the soil, from which it absorbs water and ions, which are crucial for the life of the entire organism. Roots evolved later than shoots as an adaptation to life on land.

The shoot system consists of stems and leaves. The stems serve as the site of the leaves, the main participants in photosynthesis. The location, size, and other features of the leaves are critical to the productive production of organic matter. Flowers, fruits, and seeds are the reproductive organs of the plant and are also formed on the shoot.

The recurrent node of a vegetative shoot consists of an internode, a node, a leaf, and an axillary bud. The axillary bud is the lateral apex of the shoot that allows the plant to branch out or replace the main shoot if it has been eaten by an herbivore. When the plant enters the flowering phase, the axillary buds can produce flowers.

Roots and shoots are composed of three basic types of tissues
Covering, conductive, and mechanical. In addition to these, the body contains basic, secretory, and educational tissues. Their cell types can be distinguished by their size, location relative to each other, whether they are alive or dead, and in maturity by the thickness of their cellulose cell wall. Some cells contain only one main cell wall, synthesized by the protoplast near the plasmalemma. Microtubules align within the cytoplasm and determine the direction of the cellulose fibers. The mechanical tissue cells that support the plant have stronger cell walls with multiple layers of cellulose and other reinforcing molecules, including lignin and pectin. The cellulose layers are stacked on top of each other at an angle.
Covering and vascular tissues run through the root and stem, so they are called tissue systems. The main covering tissue is the epidermis, in most plants it is one cellular layer thick. It creates external protection. The cells of the main tissue mainly carry out photosynthesis, the mechanical ones give strength to the plant, the vascular ones conduct solutions, and the educational cells divide and replenish other tissues of the body.

New growth comes at the expense of meristems
When a seed germinates, only a tiny embryonic plant exists in it. Although embryonic cells can undergo division and differentiation, the fate of most future adult cells is already predetermined.

The further development of the plant depends on the activity of meristems, which are located at the tips of shoots and roots, as well as in other parts of the plant. Initially meristem cells are undifferentiated, its cells can divide endlessly and give rise to many types of tissues.

Meristems are a cluster of small cells with a dense cytoplasm and a large nucleus, which act like animal stem cells. That is, one cell divides to give rise to two cells, of which one remains meristematic and the other undergoes a change and becomes part of some plant tissue. In this way, the population of meristem cells is constantly renewed. Meristems in the plant are found in the shoot and root apices, under the bark (cambium). The first two allow it to grow taller and deeper into the soil, the subcortical cambium contributes to the thickening of the stem.