What Are the Modifications of the Stem? | Biology | Extraclass.com

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This video will help you to learn What Are The Modifications Of The Stem?

Have you ever stopped to take a look at the plants around you and think about the stems??

The stem is the ascending part of the plant bearing branches, leaves, flowers, and fruits.

The stem has two parts:- nodes and internodes.

Nodes are the parts of the stem where leaves are grown While the internode is the portion between two nodes.
Beside this stem’s undergo modifications in order to perform the additional function like storage, support, vegetative propagation.
In this video, we will learn about the different modifications of a stem

(1) Aerial modifications

It is the modification to aerial stems and floral buds of plants that perform the function such as climbing, protection, synthesis of food, etc.

Different examples of the aerial modifications are-
Tendrils

They are the modified axillary buds of the stems. They're slender and spirally coiled. It helps the plant in climbing.

Example - Vitis
Phylloclade

Plants of arid regions modify their stems into flattened
Structures to reduce water loss called phylloclade, resembling leaves.

Example - Phyllanthus.
Thorns

Axillary buds of stems sometimes get modified into woody, straight and pointed structures called thorns

Example - Hygrophila and Carissa.
Bulbils

A small bulb-like structure, in particular, one axile of the leaf, which forms a new plant if fallen.

Example - Agave
Cladode

They are flattened leaf-like stem, consisting of one internode only.

Example - Opuntia

(2) Sub-aerial modifications

These are the modifications of stem for vegetative propagation and they are of following types
Runner

It is a stem portion of the plant that tends to grow horizontally as opposed to upright like the main stem.

The end tip of the runner produces buds that develop into a new plant.

Example - Strawberry and Oxalis.
Stolon

The stems which grow at the soil surface or just below ground that form adventitious roots at the nodes, and new plants from the buds.

Example - Hawkweeds.

Offset

They are just like runners but are short and thicker and is found in aquatic plants.

Example -Eichhornia crassipes and Pistia stratiotes.
Suckers

The plants developed from other underground parts are called suckers.

Example - Chrysanthemum mentha.
Rhizome -

These are the continuously growing horizontal underground stem which puts out lateral shoots and adventitious roots at intervals but is divided into nodes and internodes.

Example - Ginger.
Tubers -

They are a much thickened underground part of a stem or rhizome, serving as a food reserve and bearing buds from which new plants develop.

Example - Potato
Corm -

The corm, sometimes called a rock bulb, is a condensed vertical rootstock with large apical buds. adventitious roots may grow either from the base or all over its body.

Example - Gladioli.
Bulb -

It is an underground modified bud with a reduced stem and fleshy scale leaves growing from it.

Example -Onion and Garlic.

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