ReproductionReproduction Reproduction = producing a new Reproduction = producing a new

copy of somethingcopy of something Reproduction can beReproduction can be

AsexualAsexual biological process by which an organism biological process by which an organism

creates a genetically similar copy of itself creates a genetically similar copy of itself without the combination of genetic material without the combination of genetic material with another individual. with another individual.

SexualSexual a biological process by which organisms a biological process by which organisms

create descendants through the combination create descendants through the combination of genetic material. These organisms have of genetic material. These organisms have two different adult sexes, male and female. two different adult sexes, male and female.

Asexual Reproduction in PlantsAsexual Reproduction in PlantsNatural Vegetative ReproductionNatural Vegetative Reproduction

Ch. 20 - Pgs 408-411Ch. 20 - Pgs 408-411 Most plants reproduce sexually Most plants reproduce sexually

but vegetative reproduction but vegetative reproduction involving roots, stems and leaves involving roots, stems and leaves is also common.is also common.

Cambium and epidermal tissues Cambium and epidermal tissues differentiate to form a new plantdifferentiate to form a new plant

1. Bulbs1. Bulbs A short A short

underground stem underground stem surrounded by surrounded by thick fleshy leaves thick fleshy leaves that contain stored that contain stored food.food.

As the plant grows As the plant grows new bulbs sprout new bulbs sprout from the old one. from the old one. Each bulb can give Each bulb can give rise to a new plant.rise to a new plant.

2. Tubers2. Tubers

Underground storage stems from Underground storage stems from which new plants can grow after which new plants can grow after a dormant season.a dormant season.

““Eyes” – indentations on a tuber Eyes” – indentations on a tuber that can give rise to new plants.that can give rise to new plants.

The new stem uses the stored The new stem uses the stored food until in can carry on food until in can carry on photosynthesis.photosynthesis.

Mountain Buffalo

3. Stolons3. Stolons An above ground runner from which plants An above ground runner from which plants

roots can grow to start off a new plant.roots can grow to start off a new plant. Where buds from a runner touch the ground, Where buds from a runner touch the ground,

new independent plants can grow.new independent plants can grow.

4. Rhizomes4. Rhizomes An underground runner that gives rise to new plants.An underground runner that gives rise to new plants. Rhizomes are usually thick, fleshy and stores foodRhizomes are usually thick, fleshy and stores food Plants arise from nodes on the rhizome.Plants arise from nodes on the rhizome.

Artificial Vegetative Artificial Vegetative ReproductionReproduction

Common in horticultural Common in horticultural production (fruits & production (fruits & vegetables).vegetables).

These techniques allow These techniques allow producers to grow plants producers to grow plants with desirable traits.with desirable traits.

1. Cuttings (2 Types)1. Cuttings (2 Types)a)a) Stem Cuttings – a Stem Cuttings – a

branch, or slip, is cut branch, or slip, is cut from a plant and from a plant and placed in water or placed in water or moist sand. Usually moist sand. Usually the bottom of the the bottom of the clipping is dipped clipping is dipped into hormones to into hormones to promote root promote root development. Which development. Which hormones?hormones?

Common with Common with geraniums, roses, ivy geraniums, roses, ivy and grapevines.and grapevines.

b)b) Leaf Cutting – A leaf or part of a leaf is Leaf Cutting – A leaf or part of a leaf is placed in water or moist soil. A new placed in water or moist soil. A new plant will arise from the base of the leaf.plant will arise from the base of the leaf.

Common with African violet, snake plant Common with African violet, snake plant and begonias.and begonias.

2. Layering2. Layering

A stem is bent over so that part of A stem is bent over so that part of it is covered with soil. The it is covered with soil. The covered part will develop roots covered part will develop roots and the cut from the parent plant and the cut from the parent plant and replanted as a new plant.and replanted as a new plant.

Common with raspberries, roses Common with raspberries, roses and honeysuckle. and honeysuckle.

This also occurs naturally.This also occurs naturally.

Air Layering

Trench Layering Tip Layering

3. Grafting3. Grafting A stem or bud is removed from one A stem or bud is removed from one

plant and permanently joined to the plant and permanently joined to the stem of a closely related plant.stem of a closely related plant.

The 2 parts are held together by tape, The 2 parts are held together by tape, wax or commercial grafting wax or commercial grafting compounds.compounds.

The part providing the root is called The part providing the root is called the stock and the bud is called the the stock and the bud is called the scion.scion.

The scion will keep its characteristics The scion will keep its characteristics on the new root stock.on the new root stock.

Advantages of Vegetative Advantages of Vegetative PropagationPropagation

Decreases variation in crops.Decreases variation in crops. Faster reproduction than by Faster reproduction than by

seed.seed. Fruit will be produced faster Fruit will be produced faster

through grafting.through grafting. Plants bearing seedless fruit Plants bearing seedless fruit

can reproduce by this method.can reproduce by this method.

Sexual Reproduction in Sexual Reproduction in AngiospermsAngiosperms

Angiosperms reproduce Angiosperms reproduce sexually through flowers.sexually through flowers.

Seeds are protected within Seeds are protected within the ovary of the flower which the ovary of the flower which develops into a fruit.develops into a fruit.

Parts of the FlowerParts of the Flower The sepals are the green “leaves” that encase The sepals are the green “leaves” that encase

the flower before it blooms. All of the sepals the flower before it blooms. All of the sepals form the calyx at the base of the flower.form the calyx at the base of the flower.

All of the petals of the flower make up the All of the petals of the flower make up the corolla.corolla.

Parts of the FlowerParts of the Flower The anther and the filament make up the The anther and the filament make up the

stamen = male parts of the flower. stamen = male parts of the flower. The anther produces the sperm which is The anther produces the sperm which is

encased in the pollen for transport to the encased in the pollen for transport to the female flower parts.female flower parts.

Parts of the FlowerParts of the Flower The stigma, style and ovary make up the pistil = The stigma, style and ovary make up the pistil =

female flower parts.female flower parts. The stigma is where the pollen attaches; the style is The stigma is where the pollen attaches; the style is

the structure the pollen tube must grow through to the structure the pollen tube must grow through to reach the ovary which produces the egg. When the reach the ovary which produces the egg. When the egg is fertilized it creates the seed and the ovary egg is fertilized it creates the seed and the ovary becomes the fruit to protect the seeds.becomes the fruit to protect the seeds.

Fertilization of a FlowerFertilization of a Flower

Self – Pollination of Self – Pollination of FlowersFlowers Pollen is transferred from the anther to the Pollen is transferred from the anther to the

stigma on the same plant.stigma on the same plant. This is not ideal because the inbreeding limits This is not ideal because the inbreeding limits

them geneticallythem genetically.. There are three common advantages: There are three common advantages:

1.1. A given genotype may be particularly adapted to an A given genotype may be particularly adapted to an environment. Self-pollination helps keep this trait environment. Self-pollination helps keep this trait static. static.

2.2. Self-pollinating plants are not dependent on Self-pollinating plants are not dependent on pollination agents. pollination agents.

3.3. Self-pollination is an advantage when the number of Self-pollination is an advantage when the number of individuals is small or widely spaced. individuals is small or widely spaced.

Cross Pollination of Cross Pollination of FlowersFlowers This process is by which a flower is This process is by which a flower is

fertilized by the pollen from another fertilized by the pollen from another plant of the same species.plant of the same species.

The advantages of cross-pollination are The advantages of cross-pollination are genetic in nature. This creates genetic genetic in nature. This creates genetic diversity in the plant population and diversity in the plant population and reduces inbreeding.reduces inbreeding.

Mechanisms of cross pollination are Mechanisms of cross pollination are insects, wind, chemical suppressants, insects, wind, chemical suppressants, separate male and female flowers or separate male and female flowers or plants, animals and genetic plants, animals and genetic incompatibilityincompatibility

Types of FruitTypes of Fruit

1.1. Simple Fruit – Fruit that Simple Fruit – Fruit that develops from a single ovary.develops from a single ovary.

2. Aggregate Fruit2. Aggregate Fruit

Fruit is produced from a single Fruit is produced from a single flower that has many ovaries.flower that has many ovaries.

3. Multiple Fruit3. Multiple Fruit Simple fruits of many flowers fuse Simple fruits of many flowers fuse

together.together.

A – Jackfruit

B – Pineapple

C - Breadfruit

Structure of the SeedStructure of the Seed Made up of the seed coat, embryo Made up of the seed coat, embryo

and endosperm.and endosperm. All seed plants have at least one All seed plants have at least one

seed leaf or cotyledon.seed leaf or cotyledon. Monocot seeds have an endosperm Monocot seeds have an endosperm

in which food is stored for the in which food is stored for the developing embryo.developing embryo.

Food is stored in the 2 cotyledons of Food is stored in the 2 cotyledons of dicot seeds for the embryo.dicot seeds for the embryo.

Structure of the Seed Structure of the Seed (cont.)(cont.) Before the seed can germinate, water Before the seed can germinate, water

has to enter the seed.has to enter the seed. Water enter through a structure Water enter through a structure

called the micropyle. This is a small called the micropyle. This is a small hole in the seed coat that allows water hole in the seed coat that allows water to enter and allow for germination.to enter and allow for germination.

Seeds can remain dormant for long Seeds can remain dormant for long periods of time until conditions periods of time until conditions become right for germination.become right for germination.

Structure of the Seed Structure of the Seed (cont.)(cont.) In addition to the cotyledons, the embryo In addition to the cotyledons, the embryo

has 3 parts:has 3 parts:

1.1. Epicotyl (Plumule)– The part of the Epicotyl (Plumule)– The part of the embryo above the point of attachment of embryo above the point of attachment of the cotyledons. Gives rise to the leaves the cotyledons. Gives rise to the leaves and upper stem.and upper stem.

2.2. Hypocotyl – below the point of Hypocotyl – below the point of attachment but above the radicle. Gives attachment but above the radicle. Gives rise to the lower stem.rise to the lower stem.

3.3. Radicle – lower part of the embryo. Radicle – lower part of the embryo. Forms the roots of the plant.Forms the roots of the plant.

radicle

epicotyl

Dispersal of Seeds1. Water. eg. Water Lilly

2. Wind. eg. Dandelion

3. Animal fur. eg. Cockleburr

4. Through animal digestive tract spread with feces. Eg. Mountain ash, choke- cherry, strawberry and saskatoon berry