11REPRODUCTION IN PLANTS

ByDr. Arshad Keethadath

PLANT PARTS

REPRODUCTION IN PLANTS

Reproduction is the process of producing young ones from their parents

ASEXUAL REPRODUCTION

Single Parent is involvedSimple division of a plant body into two or more Parts or formation of spores

SEXUAL REPRODUCTION

Two parents are involvedFusion of male and femalegametes produce zygote which develop into seed

VEGETATIVE REPRODUCTION

Cell, tissue or part of an organof a plant develops into a new organism

ASEXUAL REPRODUCTION

Formation of new plants from the cells of a single parent

BUDDINGA small bulb-like cellular out growth, called bud is

formed on parent cell that develops into an

independent organism.YEAST

SPORE FORMATIONParent plant produce microscopic single or multi -celled spherical

bodies which germinate into new plants during favourable condition.

Ferns, Mosses

FRAGMENTATIONThe adult organism breaks up into two or more pieces

called fragments, which grows to become a new

plantAlgae – Spirogyra, Fucus

VEGETATIVE REPRODUCTION

Plants vegetative parts such as root, stem and leaf is used to produce new plants

NATURAL METHODRootsStems

(RhizomesBulbs

TubersCorms)Leaves

ARTIFICIAL METHODCuttingGraftingLayering

Tissue culture

ROOTSTuberous roots of Dahlia, sweet potato and Asparagus

STEMSMost common for vegetative propagation

Different kinds

Runners

Underground Stem

Oxalis and grass

Chrysanthemum and mint

Vallisneria

Rhizomes

Bulbs

Tubers

Coms

Oxalis and grass

Horizontal stems will produce new roots at nodes and then shoot grow upwards forming new plants at frequent intervals

Chrysanthemum and mint

Horizontal stems arise from the base of the erect shoot come out to form new aerial shoots and it become independent plants

Vallisneria

Arched stems which cross over small obstacles develop small plantlets at their nodes

Runners

Underground Stem

Rhizomes

Bulbs

Ginger, turmeric and banana

Onions

Tubers

Coms

Buds in the eyes give rise to new plants - Potato

Lots of rhizomes joined which develop into new plants - Gladiolus

LEAVESLeaves develop small buds called adventitious buds, on their margin. This grow into new plant once get touch with soil

Bryophyllum

ARTIFICIAL METHODS• CUTTING

• GRAFTING

• LAYERING

• TISSUE CULTURE

SEXUAL REPRODUCTION

• Carried out by flowering plants• Flowers are the reproductive organs of a plant

The sexual reproduction is the formation of new plants through the fusion of male and female gametes

Complete or Bisexual FlowersContains both male and female reproductive cellsHave all the four parts-Sepals-Petals-Stamens-Pistils

Incomplete or unisexual FlowersContains either male or female reproductive cellsHave only three parts-Sepals-Petals-Stamens or Pistils

Example: Hibiscus, CitrusExample: papaya, corn

STAMENS (Male Organ)Bear Anthers – contain pollen grains which produce male cells/gametes

PISTLE (Female Organ)Composed of Stigma, style and ovary.The ovary produce female cells/gametes

Mature plant flowers Pollination Fertilization

FruitsSeedsNew Plants

POLLINATIONTransfer of pollen grains from anther to the stigma of a flower is known

as pollination• Is the first step in the process of seed formation

Two Types

Cross-pollinationPollen grains are transferred from anther of one flower to the stigma of another flower of same kind (different plants)

Self-pollinationPollen grains are transferred from anther to the stigma of the same flower

AGENTS OF POLLINATION

1. WindWind blows away pollen grains from the anthers of one

flower to the stigma of another flower

Features of flowers – - Small.- Not brightly coloured.- Do not produce nectar.

Features of pollen grains –- Very light- Produced in large numbers

Examples: Pollination in wheat, rice and maize

2. WaterPollen grains are released into the water are carried out by

water current to other flowers.

Example: Aquatic plants such as sea grass and Vallisnaria

3. InsectsInsects visit flowers for nectar – Some pollen grains stick to the body parts of

these insects – when these insects visit another flower, the pollen grains fall on the stigma

Features of flowers – - Sweet smell.- Brightly coloured petals

for diurnal insects. Eg. Rose,

sun flower- White/light green petals

for nocturnal insects. Eg. Jasmine

and Cacti- Rich in nectar.

Features of pollen grains- Sticky pollen grains

FERTILIZATION

After successful pollination the stigma secrete nutrients

Pollen grains absorbs these and start growing in the form of a thin tube called pollen tube until it reaches the ovule inside ovary.

Then releases male gamete into the ovule – fertilization takes place – results in the formation of zygote

The process of fusion of male and female gamete is called fertilization

FRUIT AND SEED FORMATION

• After Fertilization ovary enlarges to form the fruit

• The wall of the ovary become the fruit wall

• The ovules become seeds – a fruit may have one or more seeds

• Petals, sepals and other parts of the flower usually dry up and fall off

The fruit is the seed-bearing part or the ripened ovary of the flowering plant

The seed is the ripened ovule which contains an embryo and is a covered by a protective coat

The process by which the embryo in the seed becomes active and begins to grow into a new plant is called germination

SEED DISPERSALThe process by which seeds or fruits are scattered is

called dispersal

Dispersal takes place by several mechanism• Dispersal by Explosion:

Pea plants, castor and balsam• Dispersal by Wind:

Dandelion, drumstick and maple• Dispersal by Water: Coconut• Dispersal by Animals:

Plants having fleshy fruits