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The stem is the aerial part of the plant in charge of, among other functions, providing support and structure to it. However, although we have mentioned that we know it, in general, as an aerial part of the plant, there are also types of stems that grow underground.
In this Green Ecologist text we bring you all the information you need to understand the importance of the stem in plants. Here we will talk about the parts of the stem and their functions, as well as the differentiation that exists between the various types of stems present in the plant kingdom.
What is stem
We can define the stem as the part of the plant that grows in the opposite direction of the root. In addition, he is in charge of carrying the water, nutrients and mineral salts to all parts of the plant to facilitate the energy exchange that occurs during photosynthesis. These are more plant stem characteristics:
- The stem originates from the yémula or plumule of the embryo of a seed.
- It is the organ of support of the plant, in charge of giving subjection not only to the leaves, but also to the flowers and fruits.
- The stems have terminal buds from which both flowers and new branches will sprout.
- In addition, it has negative geotropism, that is, they go in the opposite direction to the earth, and positive phototropism, that is, they go in a positive direction towards the light. This is what causes most of them to grow upwards and contrary to the roots.
The main parts of the stem and the functions of each
The stem structure it is divided into several parts. In a general and orderly manner, there are the following parts of a stem:
- Neck: this part is located right at the junction between the root and the beginning of it.
- Knots: They are small nodules that appear along the stem and indicate the birth of the leaves.
- Internodes: are the spaces between two consecutive nodes. In general the internodes diminish as we approach the apex of the stem.
- Armpit: It is the exact point of attachment between the branch or the leaf.
- Vegetative apex: located at the end of the stem, it is a set of meristematic cells in a constant process of separation and protected by a cluster of leaves that gives rise to what is known as the terminal bud. From it the flower and the fruit will be born.
- Yolks: They are the small shoots that appear in each armpit and that indicate the growth of a new branch. The buds are held by an insertion point between the leaf and the axilla and there are several types: the terminal buds, located at the upper end, the lateral buds, generally located between the nodes, and the adventitious buds, which are located at the Whole plant.
Plant stem functions
After knowing the parts of the stem and the specific functions of each one, we can address the issue of functions of the stem in the structure of a plant.
- Support the entire aerial part of the plant.
- Transport nutrients and substances through the interior of the plant. Here you can learn more about the topic of Plant Nutrition.
- Transport from the raw sap from the root until it reaches the leaves thanks to the use of the stem ducts, where it is enriched with carbon dioxide and the so-called processed sap is created, the main food of the plant.
We recommend you learn more about the stem and other parts of plants with this other post about the Parts of a plant and their functions.
Stem types
In general, we can sort the stems for their consistency, duration and medium in which they live.
Stem types according to their consistency
- Woody: typical of trees and shrubs.
- Semi-woody: typical of flowering plants or riverside plants.
- Herbaceous: typical of vegetables and wild plants.
Stem types according to their duration
- Annuals: typical of plants with one year of life.
- Biannuals: typical of plants with two years of life.
- Perennials: typical of trees and large shrubs.
Stem types according to the environment in which they live
- Aerial stems.
- Underground stems.
- Aquatic stems.
Aerial stems
This type of stem is divided into four types.
- Stem: one that offers consistency to herbaceous
- Trunk: woody stem that generally takes a cylindrical shape and is present in trees and shrubs.
- Cane: semi-woody stem, also cylindrical in shape, formed by knots and internodes that, on occasions, are usually hollow and have sheathing leaves.
- Stipe: cylindrical stem that usually ends in a tuft of leaves and with a single terminal. Name by which the stem of palm trees is known.
Underground stems
They are classified into rhizomes, tubers and bulbs. Sometimes they are confused with roots.
- Rhizomes: horizontally growing stems, they have buds on their upper face and in turn make aerial organs to facilitate the storage of reserve substances.
- Tubers: stems thickened with stored reserve substances that also have buds capable of creating a new plant.
- Bulbs: stems composed of a single structure that widens to produce several buds in the upper part, and with adventitious roots in the lower part. Generally spherical in shape and covered by a bed of scaly leaves to protect the seed.
Aquatic stems
They are what make up the aquatic plants, whether they are fixed, floating or submerged. They are normally of a very intense green color and a fleshy texture.
We invite you to discover this topic in more detail with this other Green Ecologist article on the different types of stems.
If you want to read more articles similar to Stem parts and their functions, we recommend that you enter our Biology category.
