Vegetative Propagation | Examples | Seed vs. Vegetative Propagation | Artificial Propagation
Asexual formation of new plants that develop from multicellular structures that grow by mitosis and become separated from the parent plant.
Stem Example of Vegetative Propagation: potato tuber
Textbook Diagram: Potato Plant and its Tubers
- The potato tuber is a stem modified for winter survival and asexual reproduction.
- The tuber ‘germinates’ in spring growing into a new plant.
- The potato plant forms many underground stem tubers during the growing season.
- The aerial parts die away at the end of the season and the tubers survive.
Root Example of Vegetative Propagation: root tuber
Textbook Diagram: Root Tubers of Orchid or Dahlia
- The root tuber is a root modified for winter survival and asexual reproduction.
- Some of the roots become greatly swollen with food reserve.
- The aerial parts die down at the end of the season.
- The root tubers survive each with the base of a stem containing buds.
- Buds on the stem bases germinate in spring forming new plants fuelled with food from the tuber.
Leaf Example of Vegetative Propagation: plantlets of Bryophyllum (‘mother of thousands’)
Textbook Diagram: Bryophyllum plant.
- Small plants develop at the margins of the leaves.
- The plantlets fall off the leaf and will grow into a new plant if the conditions are suitable.
Bulb Example of Vegetative Propagation: onion bulb
Textbook Diagram: longitudinal section of onion bulb.
- The onion bulb is a short stem carrying fleshy leaves, axillary buds and a terminal bud.
- The terminal bud of the bulb develops into a new plant in the growing season.
- At the end of the season food is transported to one or more axillary buds.
- These buds become swollen with food each forming a new bulb.
Comparing Reproduction by Seed and Vegetative Propagation
- Greater genetic variation by seed – population is better adapted to survive environmental change.
- Greater dispersal by seed – less competition and greater colonisation of new habitats.
- Greater number of offspring by seed: greater success in local habitat
- Less food reserve per individual by seed: reduced success on germination.
- Genetic similarity by vegetative propagation: more successful colonisation of stable habitat.
Textbook Diagram: cutting set up.
- Cutting is the detachment of part of a plant to grow a new plant.
- Young healthy lateral branches are suitable.
- Some of the leaves may be removed to reduce transpiration and so conserve water.
- Place cut end of stem into well-drained aerated compost.
- A new root system develops at the cut end.
- Advantages: fast, easy, cheap and new plants are genetically identical to parent plant.
Textbook Diagram: grafting procedure.
- Grafting produces new plants by joining a branch of the desired shoot system (scion) of one plant onto the vigorous root system (rootstock) of another.
- Complementary shaped cuts are made in stem of scion and rootstock.
- The scion stem is joined to the rootstock stem.
- The meristematic tissue of scion and rootstock are in contact and its growth unites them.
- Advantages: fast, flowers and fruit are identical to the scion parent.
- A young healthy stem is bent into a small hole with the terminal bud above soil level.
- The hole is filled with soil.
- A new root system develops at an underground node.
- The terminal bud forms a new shoot system.
- The new plant can then be separated from the ‘parent stem’.
Tissue Culturing (Micropropagation)
Textbook Diagram: tissue culturing set up.
- Remove a very small sample of meristematic tissue from the tip of a branch.
- This tissue sample is likely to be free of virus infection.
- Place the tissue sample on sterile nutrient agar in a dish.
- Plant growth regulators can be added to stimulate and control development.
- A plantlet will grow from the tissue sample.
- Transfer to a suitable compost for further growth.