Asexual reproduction and vegetative propagation in plants
In asexual reproduction one parent makes offspring without gametes. In vegetative propagation, new plants grow from roots, stems or leaves, naturally or by cutting, layering and grafting.
Kinds of asexual reproduction
| Method | What happens | Example |
|---|---|---|
| Fission | One cell splits into two (binary fission) or many (multiple fission) | Bacteria |
| Fragmentation | The body breaks into pieces; each piece grows into a new individual | Spirogyra (a green alga) |
| Budding | A small bud grows on the parent, then breaks off and lives on its own | Yeast |
| Spore formation | Tiny spores form inside a case (sporangium); each spore grows into a new individual | Rhizopus (bread mould), ferns, mosses |
Natural vegetative propagation
| Part | How it works | Examples |
|---|---|---|
| Root | Swollen roots store food and grow buds | Sweet potato, dahlia |
| Stem tuber | Underground stem with 'eyes' (buds) | Potato |
| Rhizome | Underground stem that grows sideways | Ginger, turmeric |
| Bulb | Short stem with fleshy leaves | Onion |
| Corm | Short, swollen upright underground stem | Colocasia (seppankizhangu) |
| Runner | Thin stem that creeps on the soil and roots at its nodes | Grass (arugampul), vallarai (Centella) |
| Leaf | Buds in the notches of the leaf margin grow into new plants | Bryophyllum |
Artificial vegetative propagation
| Method | How it is done | Examples |
|---|---|---|
| Cutting | A piece of stem with buds is planted in moist soil. It grows roots and shoots. | Rose, hibiscus, sugarcane, drumstick (moringa) |
| Layering | A low branch is bent and covered with soil while still joined to the parent. Once it roots, it is cut free. | Jasmine, grapevine |
| Grafting | A shoot (scion) of a good variety is joined to a rooted plant (stock) and tied until they grow together. | Mango, citrus, rose |
Vegetative propagation: advantages vs disadvantages
Farmers plant sugarcane setts (stem cuttings) and banana suckers, and nurseries sell grafted mango saplings that bear fruit sooner. At home, you can grow new mint or money plant from a stem piece kept in water.
1 marks: “Bryophyllum reproduces vegetatively by its ______.” Leaves (buds on the leaf margin).
2 marks: “What is vegetative propagation? Give two examples.” Growing new plants from a root, stem or leaf without seeds, e.g. potato tuber and Bryophyllum leaf.
4 marks: “Explain the artificial methods of vegetative propagation.” Cutting (rose, sugarcane); layering (jasmine); grafting with stock and scion (mango); one advantage of each or of the method.
Cut it, Lay it, Graft it. In grafting, the Stock stays in the Soil and the Scion sits on top.