To Study the Flowers Adapted to Pollination by Different Agents Such as Wind, Insects and Birds

Do you know how these colourful flowers on the plants grow? How does the pollen grain that is made in the anther lands on the stigma? What are those agents that help in carrying out pollination? Different abiotic and biotic agents help the transfer of pollen from anther to stigma where further interactions occur that ultimately leads to fertilisation. Do you know how pollination actually occurs in different plants and how each plant adapts itself?

To know more about this experiment continue reading this article. 

Table of Content 

• Aim

• Apparatus Required

• Theory 

• Procedure

• Observation

• Result

• Precautions

• Lab Manual Questions 

• Viva Questions

• Practical Based Questions 

• Conclusion

• FAQs

Aim

Study of flowers adapted to pollination by different agents such as wind, insects and birds.

Apparatus Required

• Flowers of maize, Salvia, Brassica, Hibiscus, orchid.

• Forceps

• Hand lens

• Slide

Theory 

A method where pollen grains are picked up from anther which is the male reproductive part of a flower and transferred to the stigma which is the female reproductive part of the flower is called pollination. For successful pollination, the pollen grains must be transferred to one flower from another flower of the same species. When a suitable pollen lands on the receptive stigma, pollen tube germination starts that carries the male germ cells (pollen grains) to the ovary. Once the male gamete reaches the ovary it fertilises with an egg and forms a zygote (fertilisation). The two types of pollination are self and cross pollination.

The transfer of pollen from anther to the stigma of the same flower is called self pollination. Cross pollination is the transfer of pollen from anther to the stigma of another flower. To carry out cross pollination, different pollinating agents are used such as by wind, by animals, by insects, water, birds etc.

Procedure

Observe the different flowers such as wheat, Salvia and Hibiscus with the help of a hand lens and write down the different adaptations for pollination.

Observation 

a. Maize flower (Wind Pollination)

• When we observe maize flowers, the flowers are unisexual that is they have either male (stamen) or female reproductive part (carpels) and the plant is dioecious which means that a plant contains either male part or female parts.

• The male inflorescence is terminal tassels while the female inflorescence is compound spadix and borne axillary.

• Flowers are non-attractive without any odour, colour and nectar. Flowers are small and inconspicuous. The inconspicuous flowers are those flowers which are small and not showy and hence difficult to see.

• The perianth which is the outer part of the flower consisting of calyx and corolla is reduced to small lodicules.

• Stamens  face the petals or the periphery of the flower (such condition is called extrorse) and the filament of the stamen are very long and stamen protrude outwards (this condition is called exerted). 

• Anthers are versatile (anther whose attachment is near the middle that enables them to move freely). It produces tiny, light-weight, dry, dust-like pollen grains with smooth exine.

• Gynoecium is supported on a long style coming out of the perianth and shows feathery or brush-like stigma.

• In a single breeze many flowers can get pollinated by wind if it flows in one particular direction as style and stigma are bushy.

• The maize flowers are protandrous (stamens mature early) and are pollinated by the wind. 

• When cross pollination occurs due to wind it is said to be anemophily. 

Wind Pollination

b. Salvia flower (Insect Pollination)

• Salvia flowers are bisexual, attractive and have bright coloured petals.

• When an insect lands on the flower for the nectar collection, its wings and body parts will touch the anther and stigma that will help in pollination.

• The male part matures first and this is termed as protandrous.

• They have bilipped corolla. At the mouth of the corolla tube there are two stamens present.

• The filament of anther is short and the stamens have elongated divaricate connective.

• The fertile anther lobe is on the upper branch of the connective while the lower branch of the connective bears the sterile lobe of anther.

• The two carpels fused together form the gynoecium showing long style with bifid and hairy stigma.

• The insect lands on the lower branch and pushes it down due to which the fertile lobe bends down and strikes the back of the insect and dust its pollen grains on it.

• When the same insect lands on another flower the pollen grains are picked by the receptive stigma and the pollination is affected.

• When the cross pollination occurs due to insects it is said to be entomophily.

Insect Pollination

c. Hibiscus flower (Bird Pollination)

• The petals of Hibiscus and their middle stamens form a bulls eye and help the humming birds with their long, slender bills into the flower.

• The anthers of stamen are covered with yellow pollen and five dark stigmas are present.

• Hibiscus and other flowers that rely on birds for pollination must ensure more than visual attraction such as food availability for their return.

• When cross pollination occurs due to birds it is said to be ornithophily.

Bird Pollination

Precautions

• Collect all the required flowers carefully.

• Be careful while examining each flower with a needle or a forcep.

Lab Manual Questions

1. What is pollination?

Ans: Pollination is the transfer of pollen grains from anther to stigma of the same flower or another flower of the same species by the means of different pollinating agents is called pollination.

2. Differentiate between self and cross pollination?

Ans: Self pollination is the transfer of pollen from anther of a flower to the stigma of the genetically similar flower or the same flower.

Cross pollination is the transfer of pollen from anther of a flower to the stigma of another flower. Wind, water, insects, birds etc may help in cross pollination.

3. Give reason as to why maize as well as Salvia plants show cross pollination?

Ans:  Maize shows cross pollination as it has adaptations for anemophily whereas Salvia shows cross pollination because it has adaptations for entomophily. Cross pollination by different agents like wind and insects improve seed purity and ensure a genetically diverse population.

4. Explain the term a. Autogamy, b. Allogamy and c. Geitonogamy. 

Ans: a. Autogamy:- The transfer of pollen from anther to the stigma of the same flower is called autogamy. 

b. Allogamy:- The transfer of pollen from anther of a flower to the stigma of another plant of the same species is called allogamy.

c. Geitonogamy:- The transfer of pollen from anther of a flower to the stigma of another flower of the same plant is called geitonogamy.

5. "Pollination is a prerequisite for fertilisation in flowering plants". Explain.

Ans: Pollination is very necessary in flowering flowers for the purpose of fertilisation. As both the gametes (pollen and egg) are non-motile and are produced at two different sites it is necessary for them to meet in order to fuse and form zygote. Thus, pollination helps transfer the male gametes from the anther to the stigma of the carpel.

Viva Questions

1. Which part of the flower contains pollen?

Ans: Pollens are present in the anthers of the stamen. 

2. What do biotic and abiotic pollinating agents include?

Ans: Biotic pollinating agents include animals, insects, birds etc. whereas abiotic pollinating agents include wind, water etc. 

3. Which flowers pollinate through self pollination completely?

Ans: Cleistogamous flowers pollinate through self pollination completely as they do not open at all. 

4. What are the two types of flowers found in plants that adopt autogamy?

Ans: Cleistogamous flowers and chasmogamous flowers are the two types of flowers that adopted autogamy. 

5. Is self pollination advantageous or disadvantageous?

Ans: Self pollination is disadvantageous as it leads to inbreeding depression. 

6. Why do wind pollinating flowers are not very colourful and do not produce nectar?

Ans: Wind pollinating flowers do not produce nectar and are not very colourful as these are the required for insect pollinating flowers in order to attract insects which is not a requirement in wind pollinating flowers. 

7. Give some examples of plants that produce chasmogamous and cleistogamous flowers both.

Ans: Commelina, Viola and Oxalis are the plants that produce both cleistogamous and chasmogamous flowers. 

8. What is xenogamy?

Ans: The fertilisation of a flower by a genetically different pollen is known as xenogamy. 

Practical Based Questions

1. When the pollen is transferred from anther of a flower to the stigma of another flower of a different plant, pollination is referred as:

1. Xenogamy

2. Autogamy

3. Geitonogamy

4. Siphonogamy

Answer:- A

2. The phenomenon of growth maturation of stigma and anther and stigma at the same time is called as

1. Allogamy

2. Homogamy

3. Syngamy

4. Fusion

Answer:- B. 

3. Anemophily type of pollination is found in

1. Coconut

2. Maize

3. Both A and B

4. None of the above

Answer:- C

4. What type of flowers favours cross pollination?

1. Chasmogamous flowers

2. Cleistogamous flowers

3. Unisexual flowers

4. Bisexual Flowers

Answer:- A

5. Which of the following flowers pollinate through autogamous mode?

1. Cleistogamous flowers

2. Chasmogamous flowers

3. Both A and B

4. None of the above

Answer:- Both A and B

6. Intine of pollen grain is made up of:

1. Pectin and cellulose

2. Sporopollenin

3. Lipids and proteins

4. Lipids

Answer:- C

7. Wind pollination is common in:

1. Legumes

2. Grasses

3. Orchids

4. Lilies

Answer:- B

8. Which of the following produces chasmogamous and cleistogamous flowers?

1. Viola

2. Commelina

3. Both A and B

4. None

Answer:- C

9. Advantage of cleistogamy is 

1. More vigorous offspring

2. B. Vivipary

3. C. Higher genetic variability

4. D. None of the above

Answer:- D

Conclusion

In this article, we have seen how different plants have adaptations for the purpose of pollination.

We have seen that different plants or flowers produce different types of pollen grains to carry out pollination through different agents such as wind, insects and birds.

We have also seen certain precautions taken while carrying out the procedure.