Asexual Reproduction in Plant - Natural Vegetative Reproduction

Natural vegetative reproduction:

• Natural vegetative reproduction is a form of asexual reproduction in which a bud grows and develops into a new plant.
• The buds may be formed in organs such as root, stem, and leaf.
• At some stage, the new plant gets detached from the parent plant and starts to develop into a new plant.
• Some of the organs involved in vegetative reproduction also serve as the organs of storage and perennation.
• The unit of reproductive structure used in propagation is called reproductive propagules or diaspores.

Natural methods of vegetative reproduction:

1. Vegetative reproduction in root:
   

   The roots of some plants develop vegetative or adventitious buds on them. Example Murraya, Dalbergia, and Millingtonia. Some tuberous adventitious roots apart from developing buds also store food. Example Ipomoea batatas and Dahlia. Roots possessing buds to become detached from the parent plant and grow into the independent plant under suitable condition.
   

   Reproduction by roots - Sweet potato (Ipomoea batatas)

   Reproduction by roots – Murraya

   
   
2. Vegetative reproduction in leaf:
   In some plants, adventitious buds are developed on their leaves. When they are detached from the parent plant they grow into new individual plants. Examples: Bryophyllum, Scilla, and Begonia. In Bryophyllum, the leaf is succulent and notched on its margin. Adventious buds develop at these notches and are called epiphyllous buds. They develop into new plants forming a root system and become independent plants when the leaf gets decayed. Scilla is a bulbous plant and grows in sandy soils. The foliage leaves are long and narrow and epiphyllous buds develop at their tips. These buds develop into new plants when they touch the soil.
   

   Reproduction by leaf - Bryophyllum

3. Vegetative reproduction in stem: In some plants underground modified stems are - 

   A) Underground stem:
   1. Bulb: It is a condensed conical or convex stem surrounded by fleshy scale leaves. They are of two types. Tunicated (coated) bulb: In which the stem is much condensed and surrounded by several concentric layers of scale leaves. The inner scales are commonly fleshy, the outer ones dry. They can be classified into two types (a) Simple Tunicated bulb Example: Allium cepa (b) Compound Tunicated bulb. Example: Allium sativum.

   Tunicated bulb – Allium cepa (Onion)

   Tunicated bulb - Allium sativum (Garlic)

   Naked – Lilium

   2. Corm: This is a succulent underground stem with an erect growing tip. The corm is surrounded by scale leaves and exhibit nodes and internodes. Example: Amorphophallus, Colocasia, Colchicum
   

   Corm – Colocasia

   3. Rhizome: This is an underground stem growing horizontally with several lateral growing tips. Rhizomes possess conspicuous nodes and internodes covered by scale leaves. Example: Zingiber officinale, Canna, Curcuma longa, Musa paradisiaca.
   

   Rhizome – Zingiber officinale (Ginger)

   
   4. Tuber: This is a succulent underground spherical or globose stem with many embedded axillary buds called “eyes”. Example: Solanum tuberosum, Helianthus tuberosus.
   

   Tuber – Solanum tuberosum (potato)

   
   B) Aerial steam:
   1) Creepers: These are plants growing closer (horizontally) to the ground and produce roots at each node. Example: Cynodon dactylon, Centella.
   

   Runner - Centella asiatica

   
   C) Sub-aerial stem: Sub-aerial stem is found in plants with weak stems in which branches lie horizontally on the ground. These are meant for vegetative propagation. They may be sub-aerial or partially sub-terranean.
   

   1) Runner: This is a slender, prostrate branch creeping on the ground and rooting at the nodes. Example: Oxalis (Wood sorrel), lawn grass (Cynodon dactylon).

   Runner - Oxalis

   
   2) Stolon: This is also a slender, lateral branch originating from the base of the stem. But it first grows obliquely above the ground, produces a loop and bends down towards the ground. When touches the ground it produces roots and becomes an independent plantlet. Example: Mentha piperita (peppermint), Fragaria indica (wild strawberry).
   

   Stolon - Fragaria (Strawberry)

   
   3) Sucker: Sucker develops from an underground stem and grows obliquely upwards and gives rise to a separate plantlet or new plant. Example: Chrysanthemum, Bambusa.
   

   Sucker - Chrysanthemum

   
   4) Offset: Offset is similar to runner but found in aquatic plants, especially in rosette-leaved forms. A short thick lateral branch arises from the lower Offset axil and grows horizontally leafless for a short distance, then it produces a bunch of rosette leaves and root at nodes. Example: Eichhornia Root (water hyacinth), Pistia (water lettuce).
   

   Offset - Pistia stratiotes

   Offset - Water hyacinth

   
   D) Bulbils (or specialized buds): Bulbils are modified and enlarged buds, meant for propagation. When bulbils detach from the parent plant and fall on the ground, they germinate into new plants and serve as a means of vegetative propagation. Example Agave and Allium proliferum, Dioscorea bulbifera, 
   

   Bulbil - Agave

   Axillary bulbils - Dioscorea bulbifera

5. Turions: There are special types of fleshy buds that develop in an aquatic plant which are called turions. E.g., Potamogeton, Utricularia.

Advantages of natural vegetative reproduction:

1. Only one parent is required for propagation.
2. The new individual plants produced are genetically identical.
3. In some plants, this enables them to spread rapidly. Example: Spinifex.
4. Horticulturists and farmers utilize these organs of natural vegetative reproduction for cultivation and to harvest plants in large scale.
5. It allows plants to quickly occupy available space, increasing their competitiveness and survival in their natural environment. 

Disadvantage of natural vegetative reproduction:

1. New plants produced have no genetic variation.
2. Natural vegetative reproduction results in a lack of genetic variety because all progenies are clones of the parent plant, making them more susceptible to disease and environmental changes.  
3. This uniformity can lead to the extinction of the entire colony if a single insect or disease attacks.