The 10 Types Of Plant Stems, And Their Characteristics
From a botanical point of view, the stem is the analogue of the vertebrate body in plants. This generally aerial plant part supports the leaves, flowers and fruits. Therefore, without it, key events in the life of the plant, such as photosynthesis, pollination or seed dispersal, would not be possible.
Beyond the functional importance of the stem, this structure also allows us to identify different types of vegetables, both in nature and in an agricultural setting. Human beings tend to compartmentalize each observable character in living beings, and thanks to this, dichotomous keys can be devised and manufactured, which allow the quick and easy identification of the orders, genera and species that surround us.
So, we encourage you to immerse yourself with us in the world of the types of stems in vegetables and their characteristics Of course, the complexity contained in this seemingly simple structure will leave you amazed.
Types of plant stems: a summary of their characteristics
Before starting with the types of stems themselves, we find it necessary to provide a series of data as a preface that, at least, contextualizes the situation of the plants a little from a morphological point of view.
Virtually all plant organs are made up of three tissue systems: the protective, the fundamental and the vascular The protection system is formed by the epidermis and peridermis, both located in the superficial part of the tissues. On the other hand, the fundamental system, formed by the parenchyma and supporting tissues, acts as the “beams” that maintain the shape of the plant itself in three-dimensional space. Finally we have the vascular system: formed by xylem and phloem, these tubes serve as transport routes for water and nutrients.
On the other hand, and looking strictly at the stem, we can say that this organ (generally aerial) has various functions. We define them in a few lines below:
The stem is made up of nodes and internodes The node is the place where at least one leaf develops and there is at least one axillary bud. On the other hand, internodes are, as their name indicates, the spaces between two nodes. In addition to all this, at the apical end (in the final part) the stem has an apical bud, which is the “primary” place of the emergence of the stem and can be classified according to various characteristics.
Once we have made clear the basic notions regarding plant physiology and the stem itself, it is time to delve into the types of stems according to various differential characteristics. Let’s get started.
1. Soil or dirt?
Of course, one of the first parameters to classify in the types of stems is whether they are aerial or located underground. Epigeal stems are those that grow, as their name suggests, outside the ground Depending on their growth pattern, these can be straight or ascending (if they grow vertically) or creeping, if they grow horizontally.
Hypogeal stems are, on the other hand, those that grow underground It may seem counterintuitive, but in fact, not all vegetative bodies are exposed to the aerial environment. This group presents some more peculiarities, since according to its morphology, different subtypes can be differentiated. We present some of them:
Finally, it should be noted that the hypogean stems have cataphylls, that is, each of the modified leaves that protect the buds of the plant that are at rest underground. They function as a kind of “scales” that act as armor.
2. Consistency
Of course, the stem of a grass is not the same as the trunk of a tree. Despite being the largest aerial portion of the plant in both cases, it is clear that the consistency of the tissues that make up the stem is a clear differentiating factor.
First of all we find the herbaceous stems, that is, those that constitute plants that never form permanent woody organs Secondary or adult tissues are not formed, which is why these stems have a fragile and soft constitution.
Depending on their particularities, these herbaceous stems can be of the scape, reed, calamus, voluble or climbing type. We leave the particularities of each of them for another opportunity, since we still have a lot of fabric to cut.
2. Woody stems
In the second instance we have the woody stems, those rigid and hard with a gray or brownish color, since they do not have chlorophyll in their chemical constitution In these cases, secondary tissues do develop, that is, those that provide rigidity, thickness and strength to the root and other structures, growing concentrically around them. Here we have the shrubby stems, the tree stems and the stipe stems (such as palm trees).
3. Succulent stems
Last (but not least) we have the succulent stems, those that They store a large amount of water or nutrients inside as a method of plant survival in harsh environments Clear examples of this type of stems can be those observed in cacti or aloe vera.
3. Do they photosynthesis or not?
Of course, the ability to carry out photosynthesis is also a clear differentiating element when it comes to distinguishing the different leaf structures. Photosynthetic stems are those that have evolved to perform such an important function due to an adaptive force which has promoted the disappearance of the leaves in the plant or their change to rudimentary structures.
These stems can be platyclades or cladodes The first can have the shape of a leaf, as they are green (due to the presence of chlorophyll), flattened and can extend from other more obvious branches. An example of this could be the phyllodes of acacias.
On the other hand, cladodes are flattened stems (branches) with the shape and color of a leaf. In these cases, the real leaves are too small or rudimentary to be able to fulfill their task, so with these forms of green “thorns” the stems carry out photosynthesis.
Obviously, the rest of the stems fall within the “non-photosynthetic” characteristic. Since they do not have chlorophyll and the bark of the trunks is composed of dead cells, it is physically impossible for these woody stems to perform a light absorption function.
4. Variety is the key
Finally, we cannot ignore the fact that, no matter how complex it may be, stems can also be classified. depending on the structural modifications they present to adapt to a function. According to this parameter, we can observe cauline tendrils (generally spring- or spiral-shaped, which serve to allow climbing plants to adhere), cauline spines (reduced and pointed branches that act as a defense against predators) or stolons, stems whose apical bud has the ability to form roots and give rise to a new plant.
Summary
It is difficult to believe that, beyond our sight, there is a wide range of characteristics that give names and surnames to the types of stems. These classification criteria allow us to discover the different adaptations that plants have undergone to their environment, and consequently, how they present modifications to maximize their survival in the environment in which they live.
From growth in soil or soil to photosynthetic capacity, through the consistency of its tissues and unique morphological structures, the world of stems presents variety for all tastes and needs.
