Pollination in Plants and its Types.

What is Pollination?

The process of transfer of pollen grains from anther to the stigma of flower is called as Pollination.

Types of Pollination

1.Self Pollination/ Autogamy:

The transfer of pollen grains from anther to stigma of same flower is called as Self Pollination.

Homogamy is that condition in which anther and stigma mature at same time that promotes self-pollination

In some plants the anthers bend toward stigma for pollination, carpel curls to receive pollen and in some cases movement of sepals and petals bring anther and stigma together in a same flower.

CLEISTOGAMY: The bisexual flowers that do not open are cleistogamous flowers. Pollination in cleistogamous flowers is called as cleistogamy. They are very small and not coloured. 

Examples: Viola, Oxalis, Commelina benghalensis, Drosera.

2. Geitonogamy:

The transfer of pollen grains from anther to stigma of flower on same plant or genetically similar plant is called as Geitonogamy.

3.Cross Pollination/Allogamy/Xenogamy

The transfer of pollen grains from anther of a flower to stigma of another flower that is genetically dissimilar plant is called as Allogamy/Xenogamy.

The genetically dissimilar plant must be of same species.

Conditions that prevent self-pollination and promote cross pollination:

1. Dicliny: Presence of Unisexual flowers in a plant. Example: Mulberry, Papaya.

Diocy: A condition where male and female flowers present on seperate plant

2.Self Sterility: Failure of fertilisation after self pollination.

3.Homogamy: A condition where stigma and anther of bisexual flower mature at same time

Example: In Solanum, Catharanthus, Mirabilis jalapa.

4.Dichogamy: A condition during which anther and stigma mature at different time

Protandry: If male sex organ/Anther mature first it is called as Protandry. Example: Sunflower, Clerodendron Cotton Maize etc.

Protogyny: If female sex organ/Carpel mature first it is called as Protgyny. Example: Mirabilis, Plantago etc.

5.Herkogamy: A condition where the development of anther and stigma of flowers takes place at different time. Example: In Pansy, Calotropis etc.

This condition may act as barrier for self-pollination and self-sterility.

Example: In Petunia axillaris

6.Heterostyly: Different types of flower on the basis of anther, style and pollen types.

Diheterostyly: Two types of flower: Pin eyed and Thrum eyed

Example: In Primula vulgaris, jasmine

TriHeterostyly: Three types of flower

In Lathyrus

Watch out the explanation video with Question Practice

QUESTION PRACTICE

Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R(ICAR PG Plant Science)

Assertion A: Dioecy ensures that outbreeding will always occur. 

Reason R: In dioecy, male and female flowers are present on different parts of the same plant. 

In light of the above statements, choose the most appropriate answer from the options given below

 

Both A and R are correct and R is the correct explanation of A

Both A and R are correct and R is NOT the correct explanation of A

A is correct but R is not correct 

A is not correct but R is correct 

COMMENT DOWN THE ANSWER