CHAPTER 7 PLANT REPRODUCTION

CHAPTER 7: PLAN REPRODUCTION

CHAPTER OUTLINE

7.1 Sexual Reproduction in Plants
7.2 Asexual Reproduction in Plants

7.2.1 Natural vegetative propagation
7.3.1 Artificial vegetative propagation

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CHAPTER LEARNING
OUTCOMES

At the end of this topic, the student should be able to:

DEFINE the meaning of sexual & asexual
reproduction

Explain the requirements and importance of sexual &
asexual reproduction

COMPARE the difference between sexual & asexual
reproduction.

EXPLAIN the advantages and disadvantages of sexual & asexual
reproduction.

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ASEXUAL REPRODUCTION

- In asexual reproduction, part of the parent plant is used to
generate a new plant.

• Natural vegetative propagation
• Artificial vegetative propagation

BASIC PLANT

Natural Vegetative Propagation SCIENCE

AGR

• Is a form of asexual reproduction in plants.
• It does not involve flowers, pollination and seed production.
• A new plant grows from a vegetative part, usually a stem, of the

parent plant. However, plants which reproduce asexually still have
flowers, fruits and seeds.
• Vegetative reproduction from a stem usually involves the buds.
Instead of producing a branch, the bud grows into a complete plant
which eventually becomes self-supporting.
• No gametes are involved, the plants produced asexually have
identical genomes and the offspring form what is known as a
clone.
• In some cases of vegetative reproduction, the structures involved
also become storage organs and swell with stored food, e.g.
potatoes
• The principal types of vegetative reproduction structures are bulbs,
corms, rhizomes and runners

NATURAL VEGETATIVE: BASIC PLANT
SCIENCE

AGR

• The horizontol-above ground stem
(called-stolons)

• As well as food storage

• Eg: bulbs,corms,rhizome, tubers

• Food is stored in leaves, stem @roots
and used to grow new leaves.

Food storage BASIC PLANT
SCIENCE

AGR

BULBS BASIC PLANT
SCIENCE

AGR

• Bulbs consist of very short stems with closely packed leaves
arranged in concentric circles round the stem.

• These leaves are swollen with stored food e.g. onion.
• A terminal bud will produce next year’s flowering shoot and

the lateral (axillary) buds will produce new plants

CORM BASIC PLANT
SCIENCE

AGR

• Corms also have a short stem but in this case it is
the stem itself which swells and stores food.

• The circular leaves form only papery scales.
• As with bulbs, the terminal bud grows into a

flowering shoot and the lateral buds produce
new plants

CORMS (Eg: Caladium sp) BASIC PLANT
SCIENCE

AGR

RHIZOME BASIC PLANT
SCIENCE

AGR

• Rhizomes are stems which grow horizontally under the
ground.

• In some cases the underground stems are swollen with
food reserves e.g. iris.

• The terminal bud turns upwards to produce the flowering
shoot and the lateral buds may grow out to form new
rhizomes.

RHIZOME BASIC PLANT
SCIENCE

AGR

STOLON BASIC PLANT
SCIENCE

AGR

• Also known runners, horizontal stems growing
from the parent plant, but they grow above
ground.

• When their terminal buds touch the ground
they take root and produce new plants.

Artificial Vegetative Reproduction:
Grafting

Grafting the act of placing a portion of one plant (bud or scion) into
or on a stem, root, or branch of another (stock) in such a way that a
union will be formed and the partners will continue to grow. The part
of the combination that provides the root is called the stock; the
added piece is called the scion.

Layering

 Air layering (marcotting)

 Making an incision at the node of a branch
 Dust with rooting hormone, place sphagnum

moss in plastic and wrap around the incision
forcing roots to grow on the stem of the plant

Division

 Cutting apart rhizomes, tubers, runners, stolons, or
suckers to get new plants

 Division is used on plants that grow in clumps
 Also used on some grasses

Budding

Removing the bud Bud is inserted Wound is
from the scion into the wrapped
wood. rootstock. for healing

1.
3.
5.

2. 4.

CUTTINGS (LEAF)

CUTTINGS (STEM)



Micropropagation

Micropropagation is a method of
producing a large number of
plants from a single plant in a
short time under sterile laboratory
conditions.





SEXUAL REPRODUCTION IN PLANTS?

Try to recall Chapter 5:
Morphology of Flower
– Double Fertilization



COMPARISON BASIC PLANT
SCIENCE

AGR

SEXUAL ASEXUAL
1. Complex process Simple process

2. Involve sex cells @ gamete None

3. Seed production depends on None
pollination & fertilization

4. Need external agent for None
pollination in plant

5. Germination essential None

SEXUAL BASIC PLANT
6. Variations among offspring SCIENCE
7. Resistance to disease
AGR
8. Less overcrowding &
competition ASEXUAL
None
9. Slow process Less/None

overcrowding &
high competition
Quick process

BASIC PLANT
SCIENCE

AGR

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BASIC PLANT
SCIENCE

AGR

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