TYPES OF POLLINATION.

Types of pollination.

There are two types of pollination namely;

  • Self pollination
  • Cross pollination

Self pollination

is the transfer of pollen grains from the anther heads to the stigma of the same flower

Flowers with self pollination have shorter stigma compared to their anther heads.

They also have brightly coloured petals to attract pollinators

Adaptation of flowers to self-pollination

The others and the stigma mature at the some flower.

The flower remain closed until self pollination has taken place.

The flower is hermaphrodite i.e It has both male and female parts.

Some flower are buried in the ground until self pollination takes place.

Structure illustrating self-pollination.

self pollination

W – Petals

X – Anthers

Y– Anther head

Z – Stigma

Examples of self-pollination.

Bean plant

Ground nut plant.

Simsim plant

Tomato plant

Advantages of self pollination

It helps to maintain pure breeds.

Disadvantages of self-pollination.

Flowers are difficult to pollinate because stamen sometimes donot mature at the same time as the as the pistils.

CROSS POLLINATION.

CROSS POLLINATION. Primary six science Notes.Is the transfer of pollen grains from the anther heads of one flower to the stigma of another flower but of the same type or species?

In cross–pollination, the anther heads are shorter than the stigma. 

Adaptation of flowers for cross pollination

The male and female flower occur on the same plant but mature at different time’s .i.e. the stamen may mature earlier than the pistil. E.g. maize.

The male and female flower occur on separate plants e.g. pawpaw.

The pollen grains cannot germinate on the stigma of the same flowers and if they do, fertilization cannot occur e.g. passion fruits flower.

Characteristics of cross pollination

Styles are longer than filament

Pistil and stamen are on different flowers

Reduce small amount of the grains

Stigma are higher than anthers

Advantages of cross pollination

Cross pollination can result into new materials

Cross pollination results into healthier seeds and plants

Distance of cross pollination

Cross pollination into undesirable plants reeds

Examples of plants that undergo cross pollination

Maize plants

Coconut

Pawpaw

Cow peas

Passion fruit

Illustration of cross pollination

cross pollination
image 1

Agent of pollination

These are ways or factors responsible for the transfer of grains from the another stigma.

Agents of pollination

  • Winds
  • Insects
  • Flowing water
  • Animals
  • Birds

Wind

When winds blows, pollen is transferred from another to the stigma of a flower hence pollination takes place

Characteristics of wind pollinated flowers

  1. Flowers are small and not easily seed
  2. Flowers have a dull coloured petals
  3. Flowers do not produce nectar
  4. Flowers do not have pollen grains
  5. Flowers have small and smooth and light pollen grains
  6. The flowers do not have a smell
  7. Flowers have long stigma to increase chances of pollen sticking to them

Insects

Insects are able to pollinate flowers as they visit them to collect nectar

Insects rub themselves on the anthers so on the visiting another flowers or carrying out of the flower or coming of the very flower, pollination takes place

Examples of insect pollinated flowers during day time

  • Honey bees
  • Butter flies
  • Beetles

Examples of insects that pollinate flowers during night

Moths

Characteristics of insect pollinated flower

  1. Flowers are large and easily
  2. Flowers have brightly coloured petals
  3. Flowers are well
  4. Flowers have nectar which is produced by nectarines
  5. Flower have broad compact sticky stigma
  6. Flowers have large rough and heavy pollen grains
  7. The anthers produce few pollen grains
  8. The stamens have short filaments

Birds

Birds also visit flower to get nectar which they feed on

Flowers pollinated by birds are brightly coloured

As birds are to get nectar they rub their bodies on the anthers and the stigma in the way like insects

Birds that pollinate flowers have long slender breaks which are adapted to sucking nectars from the base of the petal when found

Examples of bird that pollinate flowers

  • Sun birds
  • Humming birds

Water

Some water plants are pollinated by flowing water

The pollen floats on the top of water until if finds the stigma of such flowers

Examples of water pollinated flowers

  1. Water lily
  2. Plankton
  3. Water hyacinth

Animals

Some eating bats help in pollinating flower because they have hairy bodies on which pollen is attached

Fertilization

Fertilization is the union of the nuclei of the male and female gametes or cell to form a zygote or embryo

Fertilization takes place in the ovary

Male reproductive cells are pollen grains and female cells are ovules

Importance of pollination

  1. Pollination allows fertilization to take place in crops
  2. Pollination allows high yields in farmer’s harvest

Uses of flowers to man

  1. Flowers are used for decoration
  2. Some flowers are used as insecticides
  3. Some flowers are used for making dyes
  4. Some flowers are used as source of income after sale
  5. Some flower are also used as gifts to friends
  6. Some flowers are also eaten as food
  7. Some flowers are used for making colours

Uses of flowers to plants

  1. Flowers produce seeds and fruits
  2. Flowers attract pollinators