The Concept of Stem and Their Functions

Introduction

Stems grow from the plumule of a germinating seed as it matures. It produces a variety of leafy, fruity, and floral products. 

The nodes and internodes of a stem are the distinguishing characteristics of the stem.

 The primary function of the stem is to provide support for other parts of the plant as well as to facilitate the transport of nutrients, water, and minerals.

Some plants have modified stems, which can be aerial, subaerial, or underground in nature. 

Aerial modifications are the most common. Their function has been altered to include additional functions that are not normally associated with the stem.

Examples of the Different Types of Modifications

Modified stems can be divided into three types, as follows:

The underground parts of the plant are the rhizome, bulb, corm, and tuber. 

The subaerial parts are the runner, sucker, offsets, and stolon. 

The aerial parts are the tendrils, thorn, bulbils, and phylloclade.

1. Modifications to the underground stem

This type of organism can be found underground, as the name implies. 

They are used for a variety of purposes, including food storage, propagation, and perennation.

 In contrast to roots, they are distinguished by the presence of nodes and internodes on their branches.

 They aid in the propagation of the plant through asexual reproduction and in the survival of the plant during a period of dormancy.

 They provide protection against grazing by animals as well as environmental stresses.

2.Subaerial Stem Modifications 

These types of stems can be found on or partially beneath the surface of the ground. They are most commonly found in plants that are short-lived and have a weak and herbaceous stem, such as weeds. The stem is used in order to propagate the plant more quickly.

3.Modification of the Aerial Stem

When the aerial part of the stem and buds are modified, they can be used for a variety of functions such as support, climbing, photosynthesis, and vegetative propagation, among other things.

Purpose of a Stem in a Plant’s Structure

The stem of a plant is the portion of the plant that is above ground level.

 The bark of the tree is grey in colour, and the younger stems are green in colour. 

It is composed of leaves, flowers, and fruits, and it serves as the foundation for the shooting technique.

The primary function of a plant’s stem is to support the plant’s weight.

A stem is responsible for a wide range of functions that are critical for the proper functioning of various biochemical processes, including photosynthesis.

An accurate structure and foundation are laid down by it for a plant that will later develop into a tree.

Main function of the stem is to retain the plant buds, flowers, leaves and fruits as they develop along its length.

In addition to helping the plants stand up straight and perpendicular to the ground, a stem also aids in the growth of the roots.

It is the component of the tree that transports water and minerals from the root to many other parts of the tree and prepares food from the leaves and other sources.

Stems are one of the plant’s storerooms, where the prepared food is processed into starch form after it has been harvested.

A few stems aid in the reproduction of the plant through vegetative propagation, as well as the production of flowers and fruit.

Listed below are some examples of underground stem modification techniques:

Rhizome

It is a non-green, fleshy underground stem with nodes and internodes that is not green in colour. 

The nodes have dry scale leaves with axillary buds on the ends of the scales. 

It is also possible to see terminal buds. 

It is from the lower sides that adventitious roots emerge. 

Rootstock rhizomes are rhizome stems that grow obliquely from the base of the plant, while straggling rhizomes are stems that grow horizontally from the base of the plant. 

Banana and Alocasia are two examples of rootstock rhizomes. Ginger and turmeric are two examples of straggling rhizomes.

Modification of the Bulb

This type of modified stem has the appearance of a discoid stem that has been highly condensed. 

The upper surface is adorned with a terminal bud, and there are numerous fleshy scaled leaves to be found on the plant. 

The bulb’s base has a large number of adventitious roots that have grown from it. These bulbs may be scaly or tunicated in appearance.

 A tunic is a sheath of dry membranous scale leaves that surrounds a tunicated bulb, which is referred to as a tunic. Scaly bulbs, on the other hand, will not have any tunic to be found. 

Onions and garlic are two examples of tunicate bulbs. Lily is an example of a scaly bulb.

Stem Tendrils

Tendrils are green thread-like leafless structures that grow from the plant’s stem or branches and are used to climb up the plant’s branches or up the plant’s stem. 

These tendrils can be branched or unbranched, and a scale leaf can be seen at the point where the tendrils branch out from the main stem.

 Tendrils can be classified into four different types, which are listed below.

Axillary tendrils are a type of tendril. For instance, Passiflora Cucurbita has extra axillary tendrils, for example.

Tendrils of the apical bud: Leaf-opposed tendrils are also known as leaf-opposed tendrils, and a common example of this is a grapevine.

Floral bud tendrils, also known as inflorescence tendrils, are a type of tendril that grows from the base of a flower bud. As an illustration, consider the word Antigonon.

Thalamus is a condensed stem axis that bears floral organs such as the corolla, calyx, androecium, and gynoecium. Thalamus is also known as the flowering stem axis.

Conclusion

The stem is the axis of the plant, and it is responsible for the production of shoots, leaves, buds, and basal end-roots. 

Various systems are used to transport water, minerals, and food to and from other parts of the plant’s structure.

 In some plants, the stem has been modified to perform additional functions such as food storage, support, vegetative propagation, and protection, amongst other things. 

These are simply referred to as modified stems, and they can be divided into a number of different categories.