A Whole Orchard Can Be One Plant Copied Again and Again
Learn how sexual and asexual reproduction differ in plants, identify natural vegetative propagation by roots, stems and leaves, understand cutting, layering and grafting, and weigh these against growing from seed.
Why does every mango of one variety taste exactly the same?
Because the trees are not really separate individuals. They are copies of one original plant.
Grow a mango from a seed and you get a new plant with a new mixture of characteristics — its fruit may be smaller, sourer or simply different. Growers cannot afford that. So instead of sowing seeds they graft a shoot of the desired tree onto a rooted stock, and the resulting tree carries exactly the parent's characteristics.
Repeat that a thousand times and you have an orchard that is genetically one plant. This page covers the first part of the ICSE Class 8 Biology chapter on reproduction in plants: the two kinds of reproduction, and the many ways a plant can be multiplied without a seed.
Grow a mango from a seed and you get a new plant with a new mixture of characteristics — its fruit may be smaller, sourer or simply different. Growers cannot afford that. So instead of sowing seeds they graft a shoot of the desired tree onto a rooted stock, and the resulting tree carries exactly the parent's characteristics.
Repeat that a thousand times and you have an orchard that is genetically one plant. This page covers the first part of the ICSE Class 8 Biology chapter on reproduction in plants: the two kinds of reproduction, and the many ways a plant can be multiplied without a seed.
How does asexual reproduction differ from sexual reproduction in plants?
Sexual reproduction involves the fusion of two gametes — a male gamete from the pollen and a female gamete in the ovule. This fusion is fertilisation, and it leads to the formation of a seed.
Because two parents contribute, the offspring receives a mixture of characteristics from both and is not identical to either. This produces variation.
Asexual reproduction involves no gametes and no fertilisation. A single parent gives rise to new plants, and because there is no mixing, the offspring are genetically identical to the parent.
Its main forms in plants:
- Vegetative propagation — new plants from a vegetative part
- Budding — an outgrowth separates and grows, as in yeast
- Fragmentation — a broken piece grows into a new individual, as in Spirogyra
- Spore formation — as in ferns, mosses and moulds
Vegetative propagation is the production of a new plant from a vegetative part of the parent — its root, stem or leaf — without seeds and without fertilisation.
Why a vegetative part can do this at all. Any such part must carry a bud, and a bud contains the actively dividing tissue from which a whole new shoot can grow. A piece of stem with no bud will not sprout however carefully it is planted. This is why the eyes of a potato matter so much — each eye is a bud.
The definition to be careful with. Vegetative propagation is one type of asexual reproduction, not another name for it. Spore formation is asexual and is not vegetative propagation, so the two terms are not interchangeable — and questions are set on exactly that distinction.
Because two parents contribute, the offspring receives a mixture of characteristics from both and is not identical to either. This produces variation.
Asexual reproduction involves no gametes and no fertilisation. A single parent gives rise to new plants, and because there is no mixing, the offspring are genetically identical to the parent.
Its main forms in plants:
- Vegetative propagation — new plants from a vegetative part
- Budding — an outgrowth separates and grows, as in yeast
- Fragmentation — a broken piece grows into a new individual, as in Spirogyra
- Spore formation — as in ferns, mosses and moulds
Vegetative propagation is the production of a new plant from a vegetative part of the parent — its root, stem or leaf — without seeds and without fertilisation.
Why a vegetative part can do this at all. Any such part must carry a bud, and a bud contains the actively dividing tissue from which a whole new shoot can grow. A piece of stem with no bud will not sprout however carefully it is planted. This is why the eyes of a potato matter so much — each eye is a bud.
The definition to be careful with. Vegetative propagation is one type of asexual reproduction, not another name for it. Spore formation is asexual and is not vegetative propagation, so the two terms are not interchangeable — and questions are set on exactly that distinction.
Which plants reproduce naturally by their roots, stems and leaves?
By roots. Certain tuberous roots swell with stored food and carry buds that sprout into new plants.
Examples: sweet potato, dahlia, asparagus, tapioca.
By stems, which is the commonest route, and takes five recognisable forms.
- Runner — a slender stem creeping along the ground, rooting at its nodes and sending up shoots. Examples: doob grass, strawberry, mint, Oxalis.
- Rhizome — a thickened stem growing horizontally underground, with scale leaves and buds. Examples: ginger, turmeric, canna, and the underground stem of banana.
- Tuber — a swollen underground stem tip storing food, with buds in depressions called eyes. Example: potato. Cut a potato so that each piece carries an eye and every piece grows.
- Bulb — a short underground stem with fleshy scale leaves storing food, with a bud at the centre. Examples: onion, garlic, lily.
- Sucker — a shoot arising from the base of the parent stem, just below the soil, growing up beside it. Examples: banana, chrysanthemum, pineapple, mint.
- Corm — a short, thick, vertical underground stem. Examples: colocasia, gladiolus, saffron.
By leaves. A few plants carry buds on the leaf itself, which drop off and grow.
The classic example is Bryophyllum, whose leaf margins are notched, with a bud sitting in each notch. A leaf falling on damp soil produces a row of new plantlets along its edge. Begonia and Kalanchoe behave similarly.
Bryophyllum is worth remembering precisely because it is unusual: leaves are normally organs of photosynthesis, not of reproduction.
What all these have in common. Every one is a part that both stores food and carries a bud. The stored food feeds the new shoot until it has roots and leaves of its own, and the bud supplies the growing tissue. That is why the parts involved are almost always swollen — a thin ordinary stem has neither.
And it explains the kitchen observations everyone has made. Potatoes and onions left in a basket sprout, ginger left in a damp corner sends up shoots, and a bit of mint in water grows roots. In every case a bud with a food store has been given warmth and moisture, which is all it was waiting for.
Examples: sweet potato, dahlia, asparagus, tapioca.
By stems, which is the commonest route, and takes five recognisable forms.
- Runner — a slender stem creeping along the ground, rooting at its nodes and sending up shoots. Examples: doob grass, strawberry, mint, Oxalis.
- Rhizome — a thickened stem growing horizontally underground, with scale leaves and buds. Examples: ginger, turmeric, canna, and the underground stem of banana.
- Tuber — a swollen underground stem tip storing food, with buds in depressions called eyes. Example: potato. Cut a potato so that each piece carries an eye and every piece grows.
- Bulb — a short underground stem with fleshy scale leaves storing food, with a bud at the centre. Examples: onion, garlic, lily.
- Sucker — a shoot arising from the base of the parent stem, just below the soil, growing up beside it. Examples: banana, chrysanthemum, pineapple, mint.
- Corm — a short, thick, vertical underground stem. Examples: colocasia, gladiolus, saffron.
By leaves. A few plants carry buds on the leaf itself, which drop off and grow.
The classic example is Bryophyllum, whose leaf margins are notched, with a bud sitting in each notch. A leaf falling on damp soil produces a row of new plantlets along its edge. Begonia and Kalanchoe behave similarly.
Bryophyllum is worth remembering precisely because it is unusual: leaves are normally organs of photosynthesis, not of reproduction.
What all these have in common. Every one is a part that both stores food and carries a bud. The stored food feeds the new shoot until it has roots and leaves of its own, and the bud supplies the growing tissue. That is why the parts involved are almost always swollen — a thin ordinary stem has neither.
And it explains the kitchen observations everyone has made. Potatoes and onions left in a basket sprout, ginger left in a damp corner sends up shoots, and a bit of mint in water grows roots. In every case a bud with a food store has been given warmth and moisture, which is all it was waiting for.
How do cutting, layering and grafting work?
These are the artificial methods — deliberately carried out by gardeners and growers.
Cutting. A piece of stem, root or leaf bearing at least one bud is cut from the parent and planted in moist soil, where it develops roots and grows into a new plant.
The cut end is often dipped in a rooting hormone to speed root formation, and the lower leaves are removed so the cutting does not lose water before it can absorb any.
Plants propagated by cutting: rose, hibiscus, sugarcane, grapevine, money plant, bougainvillea, croton.
Layering. A flexible branch of the parent plant is bent down, and the middle portion is buried in the soil while the tip stays above ground and the branch stays attached to the parent. Roots develop at the buried part, and only then is the branch cut away to become an independent plant.
The branch remaining attached is the whole point: it continues to receive food and water from the parent while it grows its own roots, so the success rate is much higher than for a cutting.
Plants propagated by layering: jasmine, guava, lemon, china rose, strawberry.
Grafting. Parts of two different plants are joined so that they grow as one.
- The stock is the rooted lower portion, chosen for a strong root system and often for disease resistance.
- The scion is the short shoot of the desired variety, chosen for the quality of its fruit or flower.
- The two are cut to matching shapes, fitted together so that their vascular tissues meet, and bound with tape or clay until they unite.
The resulting plant has the roots of the stock and the shoot, fruit and flowers of the scion.
Plants propagated by grafting: mango, apple, citrus, rose, guava.
Why the tissues must meet. Water must travel up from the stock's roots and food must travel down from the scion's leaves, so the xylem and phloem of the two pieces have to line up and join. A graft in which they do not meet simply dies, however neatly it is bandaged — which is a direct application of the vascular tissue of the transportation chapter.
A fourth modern method. Tissue culture, in which a tiny piece of plant tissue is grown in a nutrient medium under sterile conditions to produce many identical plantlets from very little material. It is used for orchids and for producing disease-free planting stock.
Cutting. A piece of stem, root or leaf bearing at least one bud is cut from the parent and planted in moist soil, where it develops roots and grows into a new plant.
The cut end is often dipped in a rooting hormone to speed root formation, and the lower leaves are removed so the cutting does not lose water before it can absorb any.
Plants propagated by cutting: rose, hibiscus, sugarcane, grapevine, money plant, bougainvillea, croton.
Layering. A flexible branch of the parent plant is bent down, and the middle portion is buried in the soil while the tip stays above ground and the branch stays attached to the parent. Roots develop at the buried part, and only then is the branch cut away to become an independent plant.
The branch remaining attached is the whole point: it continues to receive food and water from the parent while it grows its own roots, so the success rate is much higher than for a cutting.
Plants propagated by layering: jasmine, guava, lemon, china rose, strawberry.
Grafting. Parts of two different plants are joined so that they grow as one.
- The stock is the rooted lower portion, chosen for a strong root system and often for disease resistance.
- The scion is the short shoot of the desired variety, chosen for the quality of its fruit or flower.
- The two are cut to matching shapes, fitted together so that their vascular tissues meet, and bound with tape or clay until they unite.
The resulting plant has the roots of the stock and the shoot, fruit and flowers of the scion.
Plants propagated by grafting: mango, apple, citrus, rose, guava.
Why the tissues must meet. Water must travel up from the stock's roots and food must travel down from the scion's leaves, so the xylem and phloem of the two pieces have to line up and join. A graft in which they do not meet simply dies, however neatly it is bandaged — which is a direct application of the vascular tissue of the transportation chapter.
A fourth modern method. Tissue culture, in which a tiny piece of plant tissue is grown in a nutrient medium under sterile conditions to produce many identical plantlets from very little material. It is used for orchids and for producing disease-free planting stock.
Is vegetative propagation better than growing from seed?
For a grower who knows what they want, usually yes. For a species facing an uncertain future, no.
Advantages of vegetative propagation:
- Offspring are genetically identical to the parent, so a desirable quality — taste, colour, size, disease resistance — is preserved exactly.
- It is faster than growing from seed, and the plants flower and fruit earlier.
- It allows the propagation of plants that produce no viable seeds — banana, seedless grapes, pineapple, sugarcane.
- Only one parent is needed, so no pollination and no pollinator are required.
- It is cheaper and simpler, and the grower knows in advance exactly what will grow.
Disadvantages of vegetative propagation:
- There is no variation. Since every plant is identical, a disease or pest that can attack one can attack all of them, and a whole plantation can be lost to a single infection.
- There is no dispersal. New plants grow crowded around the parent, competing with it and each other for light, water and minerals.
- Over many generations the stock may lose vigour.
- No new varieties can arise, since nothing new is ever combined.
What reproduction by seeds offers instead:
- Variation, which allows a species to adapt to changing conditions and allows new and better varieties to appear.
- Dispersal by wind, water and animals, so new ground is colonised and crowding is avoided.
- Dormancy — a seed can survive drought or cold and germinate when conditions improve, and it is easy to store and transport.
Its drawbacks: it is slower, needs pollination, and the offspring are not identical to the parent, so a prized variety cannot be reproduced reliably from its own seed.
The trade-off in one line. Vegetative propagation buys certainty at the cost of variation; seeds buy variation at the cost of certainty. A grower wanting this year's mango exactly as it was chooses the first; a species needing to survive the next century depends on the second.
Which is why serious agriculture does both. Commercial orchards are propagated vegetatively for uniform fruit, while plant breeders work from seed to create the new varieties that those orchards will one day be grafted from.
Advantages of vegetative propagation:
- Offspring are genetically identical to the parent, so a desirable quality — taste, colour, size, disease resistance — is preserved exactly.
- It is faster than growing from seed, and the plants flower and fruit earlier.
- It allows the propagation of plants that produce no viable seeds — banana, seedless grapes, pineapple, sugarcane.
- Only one parent is needed, so no pollination and no pollinator are required.
- It is cheaper and simpler, and the grower knows in advance exactly what will grow.
Disadvantages of vegetative propagation:
- There is no variation. Since every plant is identical, a disease or pest that can attack one can attack all of them, and a whole plantation can be lost to a single infection.
- There is no dispersal. New plants grow crowded around the parent, competing with it and each other for light, water and minerals.
- Over many generations the stock may lose vigour.
- No new varieties can arise, since nothing new is ever combined.
What reproduction by seeds offers instead:
- Variation, which allows a species to adapt to changing conditions and allows new and better varieties to appear.
- Dispersal by wind, water and animals, so new ground is colonised and crowding is avoided.
- Dormancy — a seed can survive drought or cold and germinate when conditions improve, and it is easy to store and transport.
Its drawbacks: it is slower, needs pollination, and the offspring are not identical to the parent, so a prized variety cannot be reproduced reliably from its own seed.
The trade-off in one line. Vegetative propagation buys certainty at the cost of variation; seeds buy variation at the cost of certainty. A grower wanting this year's mango exactly as it was chooses the first; a species needing to survive the next century depends on the second.
Which is why serious agriculture does both. Commercial orchards are propagated vegetatively for uniform fruit, while plant breeders work from seed to create the new varieties that those orchards will one day be grafted from.
Exam tip
Exam tip: name the plant with every method
Every method in this chapter is marked with an example. Rhizome alone is weak; rhizome, as in ginger and turmeric is complete. Learn at least one named plant for each of runner, rhizome, tuber, bulb, sucker, corm, root and leaf.
For the artificial methods, keep the distinction sharp: in layering the branch stays attached to the parent while it roots; in a cutting it is detached first. That attachment is the difference between the two.
In grafting, name both parts and their jobs — the stock supplies the roots, the scion supplies the shoot and fruit — and say their vascular tissues must meet.
Say that a vegetative part must carry a bud, and give the eyes of a potato as the example.
Remember vegetative propagation is a type of asexual reproduction, not a synonym for it — spore formation is asexual and is not vegetative propagation.
When comparing with seeds, give both advantages and disadvantages. The two answers worth most are no variation means the whole crop is vulnerable to one disease, and plants with no viable seeds such as banana can only be propagated vegetatively.
And use Bryophyllum for reproduction by leaves, specifying the buds in the leaf notches.
For the artificial methods, keep the distinction sharp: in layering the branch stays attached to the parent while it roots; in a cutting it is detached first. That attachment is the difference between the two.
In grafting, name both parts and their jobs — the stock supplies the roots, the scion supplies the shoot and fruit — and say their vascular tissues must meet.
Say that a vegetative part must carry a bud, and give the eyes of a potato as the example.
Remember vegetative propagation is a type of asexual reproduction, not a synonym for it — spore formation is asexual and is not vegetative propagation.
When comparing with seeds, give both advantages and disadvantages. The two answers worth most are no variation means the whole crop is vulnerable to one disease, and plants with no viable seeds such as banana can only be propagated vegetatively.
And use Bryophyllum for reproduction by leaves, specifying the buds in the leaf notches.
Did you know
Why does a banana plant have no seeds to plant?
Cut open a banana and the tiny black specks down its centre are all that remain of its seeds. They cannot grow. A banana plant, in the ordinary sense, cannot reproduce itself at all.
Every banana plant in a plantation is therefore grown from a sucker — a shoot arising from the base of an existing plant, dug up and planted elsewhere. The variety has been multiplied this way for a very long time, which means the plants are effectively one enormous individual spread across the world.
That uniformity is exactly what makes bananas so convenient and so precarious. Every fruit of a variety looks, keeps and tastes the same, which suits growers and shippers. But since there is no genetic variation anywhere in the crop, a disease that can kill one plant can kill every plant, and there are no naturally resistant individuals for it to run into.
It is the disadvantage listed in the previous section, made concrete on a global scale — and the reason plant breeders work so hard on a fruit that appears to need no improving.
Every banana plant in a plantation is therefore grown from a sucker — a shoot arising from the base of an existing plant, dug up and planted elsewhere. The variety has been multiplied this way for a very long time, which means the plants are effectively one enormous individual spread across the world.
That uniformity is exactly what makes bananas so convenient and so precarious. Every fruit of a variety looks, keeps and tastes the same, which suits growers and shippers. But since there is no genetic variation anywhere in the crop, a disease that can kill one plant can kill every plant, and there are no naturally resistant individuals for it to run into.
It is the disadvantage listed in the previous section, made concrete on a global scale — and the reason plant breeders work so hard on a fruit that appears to need no improving.
Key takeaways
Vegetative propagation: quick revision
- Sexual reproduction needs two gametes and fertilisation, forms a seed, and produces variation.
- Asexual reproduction needs no gametes, uses one parent, and gives genetically identical offspring. Its forms include vegetative propagation, budding, fragmentation and spore formation.
- Vegetative propagation produces a new plant from a root, stem or leaf. It is one type of asexual reproduction, not a synonym for it.
- Any such part must carry a bud — the eyes of a potato are buds — and usually a food store to feed the new shoot.
- By roots: sweet potato, dahlia, asparagus, tapioca.
- By stems: runner (doob grass, strawberry, mint), rhizome (ginger, turmeric, banana), tuber (potato, with eyes), bulb (onion, garlic, lily), sucker (banana, chrysanthemum, pineapple), corm (colocasia, gladiolus).
- By leaves: Bryophyllum, with buds in the leaf notches; also Begonia.
- Cutting — a detached piece bearing a bud is planted: rose, hibiscus, sugarcane, grapevine, money plant.
- Layering — a branch is buried while still attached to the parent, rooted, then cut away: jasmine, guava, lemon, china rose.
- Grafting — the stock gives the roots, the scion gives the shoot and fruit, and their vascular tissues must meet: mango, apple, citrus, rose.
- Tissue culture grows many identical plantlets from a tiny piece of tissue.
- Advantages: offspring identical, so quality is preserved; faster, flowering earlier; works for plants with no viable seeds (banana, seedless grapes); needs one parent; cheaper.
- Disadvantages: no variation, so one disease can destroy the whole crop; no dispersal, so crowding; possible loss of vigour; no new varieties.
- Seeds give variation, dispersal and dormancy, but are slower and do not reproduce a prized variety reliably.
Test yourself by naming the method and one plant for each of the eight natural routes, then stating one advantage and one disadvantage of propagating without seeds — that is exactly how the question is set.
- Asexual reproduction needs no gametes, uses one parent, and gives genetically identical offspring. Its forms include vegetative propagation, budding, fragmentation and spore formation.
- Vegetative propagation produces a new plant from a root, stem or leaf. It is one type of asexual reproduction, not a synonym for it.
- Any such part must carry a bud — the eyes of a potato are buds — and usually a food store to feed the new shoot.
- By roots: sweet potato, dahlia, asparagus, tapioca.
- By stems: runner (doob grass, strawberry, mint), rhizome (ginger, turmeric, banana), tuber (potato, with eyes), bulb (onion, garlic, lily), sucker (banana, chrysanthemum, pineapple), corm (colocasia, gladiolus).
- By leaves: Bryophyllum, with buds in the leaf notches; also Begonia.
- Cutting — a detached piece bearing a bud is planted: rose, hibiscus, sugarcane, grapevine, money plant.
- Layering — a branch is buried while still attached to the parent, rooted, then cut away: jasmine, guava, lemon, china rose.
- Grafting — the stock gives the roots, the scion gives the shoot and fruit, and their vascular tissues must meet: mango, apple, citrus, rose.
- Tissue culture grows many identical plantlets from a tiny piece of tissue.
- Advantages: offspring identical, so quality is preserved; faster, flowering earlier; works for plants with no viable seeds (banana, seedless grapes); needs one parent; cheaper.
- Disadvantages: no variation, so one disease can destroy the whole crop; no dispersal, so crowding; possible loss of vigour; no new varieties.
- Seeds give variation, dispersal and dormancy, but are slower and do not reproduce a prized variety reliably.
Test yourself by naming the method and one plant for each of the eight natural routes, then stating one advantage and one disadvantage of propagating without seeds — that is exactly how the question is set.