FLOWERS AS REPRODUCTIVE STRUCTURES

ABBOTTS PAGE 53

FLOWER STRUCTURE PAGE 53

Parts of a Flower

Stamen (male) Anther Filament ovule DIAGRAM PAGE 53 Stigma Style Ovary Carpel/ Pistil (female) petals sepal

Parts of the Flower

         Peduncle: flower stalk Receptacle: part of stalk bearing the floral organs, at base of flower Sepal: leaflike structures at flower base, protects young flower bud Calyx: all the sepals together form the calyx Petal: located inside and above the sepals, often large and colourful, sometimes scented, sometimes producing nectar Stamen: male part of the flower, consist of the

anther

and

filament,

makes

pollen grains

Pollen: grains containing the male gametes Pistil/Carpel: female part of the flower, consist of the stigma, style and ovary Ovule: located in the ovaries, carry female gametes

FLOWER ANATOMY

Anther Filament Pollen Tube Stamen Petal Sepal Stigma Style Ovary Ovule Carpel

PURPOSE OF EACH FLOWER PART

A. Carpel

:

1. Stigma

- Covered in a sticky substance that pollen grains can stick to

2. Style-

Raises the stigma away from the ovary to decrease pollen contamination

3. Ovary-

Protects the ovule after fertilization; becomes the fruit

4. Pollen Tube-

What the pollen travels through to reach the eggs in the ovule

5. Ovule-

Like the egg in animals; once fertilization takes place it will become the seed.

PURPOSE OF EACH FLOWER PART

B. Stamen

:  

Anther-

Contain pollen sacs. The sacs release pollen on to the outside of the anthers where wind or other organisms can transfer the pollen to the carpel for fertilization.

Filament-

Stalk of the anther

C. Petal:

Petals are used to attract insects into the flower, they may have guidelines on them and be scented.

D. Sepal:

Sepals protect the flower whilst the flower is developing from a bud.

FLOWER FUNCTIONS  Flowers contain the reproductive organs   Stamens – male parts Carpel – female part  Flowers attract pollinators who transport pollen from the anther to the stigma PAGE 54

TO DO DRAW FLOWER IN YOUR WORKBOOK PAGE 53

DRAWING

11

       Use a sharp HB pencil Drawing must be big enough e.g. Half a page Leave enough space around the drawing for labels Labels must be written in ink and not cover the diagram itself Label lines must be in ink, drawn with a ruler and must not cross each other The line must not end with an arrow and it must indicate the exact part that is being labelled The drawing should have a heading stating what the diagram shows

POLLINATION BY POLLINATORS ADD TO WORKBOOK  Pollinators are organisms that aid in the transfer of pollen from anther to stigma, to allow for fertilization  Flowers get pollinated and pollinators get food Pollination takes place through: insects wind birds water

POLLINATION

PAGE 54

13

 Is the transfer of ripe pollen containing the male gametes from the anthers to the stigma to allow for fertilization

14

Self Pollination = when the pollen from one flower is used to fertilize the eggs produced by that same flower; true-bred flowers

15

Cross Pollination = when the pollen from one flower is used to fertilize a different flower of the same type

POLLINATION BY POLLINATORS

 Pollinators are animals that move pollen from anther to stigma, to allow for fertilisation  Pollinators visit flowers to get food (pollen and nectar)  Flowers get pollinated and pollinators get food  Pollinators are mostly insects (some are vertebrates) PAGE 55

ADAPTATIONS OF INSECT-POLLINATED FLOWERS PAGE 55  The flowers have large conspicuous petals in bright colours  Sweet scent to attract moths and butterflies  Offer a reward of nectar and/pollen  Anthers and stigma are often inside the flower  Pollen grains are often sticky or spiky (stick to the insects  Large quantities of pollen are produced  Flowers have nectar guides to help the insect find the centre of the flower

SOUTH AFRICAN INSECT POLLINATED FLOWER

PAGE 56       Bluish in colour flowers – bees pollinate blue and yellow Delicate sweet scent Sturdy with a landing platform on which the bee lands Have nectaries which secrete nectar (sweet liquid) to attract and feed pollinators Flowers are open in the daytime Pollen grains stick to the bodies of bees

Salvia africana

-

caerulea

ADAPTATIONS OF BIRD POLLINATED FLOWERS PAGE 56  Flowers produce a large quantity of dilute nectar  Flowers are bigger than insect pollinated flowers    Flowers are red and open in the daytime Flowers are sturdy – birds are rough Flowers have little or no scent – birds have a poor sense of smell   Ovules are protected from the probing beaks Pollen grains stick together in clumps – bird picks up a lot of pollen in one visit  Flowers are erect with a landing platform

SOUTH AFRICAN BIRD-POLLINATED FLOWER      Flowers stand at the tips of long stalks Flowers have a sturdy landing place for sunbirds Flowers have three orange sepals and three blue petals Two of the petals join together to form a dart to hold the stamens, style and nectary Dart provides a perch for the sunbird

strelitzia reginae

PAGE 57

The structure and pollination of the flowers is fascinating. The hard, beak-like sheath from which the flower emerges, is called the spathe. This is held at right angles to the stem, and has the appearance of a bird's head. Each spathe contains 4 to 6 flowers, and these emerge one at a time from the spathe.

Each flower consists of 3 clear yellow sepals and 3 deep purple petals. The yellow sepals give the appearance of a crest on the 'bird's' head. Two of the purple petals are joined together around the stamens and the style to form an arrow-like structure. The third purple petal is visible as a small scale.

EXTRA STUFF DART FORMED BY BLUE PETALS SPATHE SEPALS

ADAPATATIONS OF A WIND POLLINATED FLOWER

         Small, inconspicuous flowers without any bright petals Petals are often absent for better exposure to wind No nectar or produced No scent Male flowers are often arranged in catkins (clusters) that move freely in the wind Long thin filaments hang outside the flower, easily shaken by the wind Anthers are large and well exposed to catch the wind Pollen grains are small (non sticky) and light and easily carried by the wind Stigmas are long and feather- like with a large surface area and outside the flower to trap pollen Page 57

Examples

of

inflorescence

types.

WORKBOOK An

inflorescence

is a group or cluster of flowers arranged on a stem

SOUTH AFRICAN WIND POLLINATED FLOWER PAGE 58  Simple flowers with all the features of wind pollinated flowers except the anthers are not visible

Thamnochortus

pellucidus in flower

Female

inflorescence

Wind distributes the pollen to the female infloresence – caught by bracts and directed to hidden female flowers Male

inflorescence

The male infloresence hangs down on a flexible stalk to shake the pollen free

DIFFERENCES BETWEEN BIRD AND INSECT POLLINATED FLOWERS

Insect Bird

Shape of flower Colour Corolla Corolla tube wide and often horizontal – suits approach flight of insects Landing platform present Not red- bee deterrent Not large or strong Corolla tube often long and narrow to suit shape of birds beak No landing platform Often red – bird attraction colour Larger and stronger Nectar Nectar guides Scent Night blooming Less nectar- stronger concentration Present – insect vision not good yes Much dilute nectar Absent – bird has excellent vision Never Sometimes – moths pollinate at night never PAGE 58

SIMILARITIES BETWEEN BIRD AND INSECT POLLINATED FLOWERS

PAGE 59       Produce less pollen than wind pollinated flowers; there is no wastage as the pollen is taken directly between plants Both produce nectar Have pollen grains with spikes etc so that they stick together and can attach easily to the pollinator Have stigmas and anthers either just outside or inside the flower Might be affected by disease organisms that are carried to the flower along with pollen Have obvious petals

DIFFERENCES BETWEEN POLLINATOR AND WIND POLLINATION

Feature

Shape of flower

Pollinator eg bird/insect

Conspicuous

Wind

inconspicuous PAGE 59 Flower Stigma Stamens Pollen Pollination process Disease transfer Energy expenditure Scent and nectar Obvious Usually quite large, coloured scented petals Often inside the flower inconspicuous Large feathery stigmas, outside Often inside the flower Fewer pollen grains, which have spikes to stick together in clumps Not wasteful Large stamens, always hang outside A lot of small,dry light pollen grains Random and wasteful Disease organisms can be transferred with the pollen Great – used for pollination, formation of nectar, etc Can be present No disease transfer Less, only used to produce pollen No scent or nectar

TO DO

TEXTBOOK PAGE 61 LEARNING ACTIVITY 18 ADAPTATIONS OF FLOWERS FOR POLLINATION

FERTILISATION

DIAGRAM PAGE 62

Fertilisation

is the combining of nuclei of a male and female gamete to form a zygote

POLLINATION

PAGE 54

33

 Is the transfer of ripe pollen containing the male gametes from the anthers to the stigma to allow for fertilization

WHAT HAPPENS AFTER FERTILISATION?

    The zygote forms an embryo inside the ovule The rest of the ovule forms endosperm (food for the germinating seed) The outer layer of the ovule forms the testa (hard, dry, protective layer) The mature ovule = seed

WHAT HAPPENS AFTER FERTILISATION?

 The ovary grows and encloses and protects the seeds =fruit

TO DO

TEXTBOOK PAGE 62 LEARNING ACTIVITY 19 POLLINATION AND FERTILISATION

 THE END