Reproduction

Regeneration

Regeneration of new plants from the vegetative parts of the parent plant is called vegetative propagation or vegetative reproduction. Vegetative propagation is done with the help of vegetative parts such as roots, stem or leaves. These parts may also be variously modified for vegetative propagation.

Natural vegetative propagation is of different types based on the vegetative organ involved.

Vegetative Propagation by Roots

Roots of some plants develop new plants either by directly producing shoots or producing buds. Shoots are produced by roots of woody plants like Dalbergia, Murraya etc. Adventitious buds are formed on the roots of plants like sweet potato, dahlia, asparagus, tapioca, etc. These buds detach from the root and develop into new plants.

Vegetative Propagation by Stem

Stem has nodes and internodes. The nodes develop leaves. In the axils of the leaves buds develop called the axillary buds. They develop into new plants on detachment from the parent plant or even when the stem portion remains attached.

There are different types of stems for vegetative propagation. They are:

Subaerial Stems

The branches that arise from the stem which is very close to the surface of the ground break off from the parent plant and develop new plants.

These branches are classified as follows:

Runners - For example, strawberry, grass, etc.

Suckers - For example, mint, Chrysanthemum

Stolon - For example, gooseberry, jasmine, etc.

Offset - For example, Eichhornia (water hyacinth), Pistia, etc.

Underground Stem

The portion of the stem that is underground, in some plants, serves two functions. It tides over unfavourable conditions by storing food and becoming dormant and then germinating with the help of axillary buds when there are favourable conditions.

The underground stems may be variously modified into the following kinds:

Tubers

The stem is swollen and the nodal regions are called the eyes.

For example: Potato

Each eye has scaly leaves and axillary buds which develop into new plants when the tuber is planted.

Rhizomes

The stem is also swollen but it is branched. The scaly leaves are bigger.

For example: Ginger, Turmeric etc.

Rhizomes also give rise to new plants from the axillary bud.

Bulb

The stem is very small and disc-like.

For example: Onion, Garlic, Lilies, etc.

From the stem arise scaly and fleshy leaves which bear buds in their axils.

Corm

The stem is very similar to tuber but they do not have definite shape.

For example: Amorphophalus, Colocasia, Gladiolus, saffron, etc.

Vegetative Propagation by Leaves

This is not very common and is seen in plants such as Bryophyllum.

It has succulent (fleshy) leaves and adventitious buds present at the margins of the leaves. These buds fall off and grow into new plants.

Know Something

Tissue Culture Tissue culture is based on the concept of cellular totipotency. That is all the multicellular organisms basically are formed from a single cell (the zygote), by repeated multiplication and differentiation. Thus a single cell can develop into a whole organism or in other words, the cell is totipotent. This is because it contains the full set of genetic information needed to make the organism. This is called cellular totipotency. Thus, a tissue can be taken from any part of the plant and put in a suitable nutrient medium. The nutrient medium is jelly-like and is taken in a test-tube. The tissue starts dividing mitotically and produces a mass of cells. This structure is undiferentiated and is called the callus. Differentiation refers to the formation of different tissues like the roots, stem, leaves, etc. The callus is transferred to other medium that contains different hormones for differentiation to occur. This differentiated mass of tissue is called the embryoid which grows into the new plantlet. The plantlets are then planted in pots and then in the fields. Here are some terms used in cell and tissue culture. The cells/tissues of the plant used for culture is called the explant. The undifferentiated mass of cells obtained from the single cell is called the callus. The embryo got from the culture is called the embryoid. The plant developed from embryoid is called the plantlet. This method of propagation is also called micropropagation since it uses only a small part of the plant. A single cell can also be separated and cultured to give rise to a new plantlet. This is called cell culture.