Practical Exercise to Observe Pollination (With Diagram)

The below mentioned article provides a practical exercise to observe pollination in flowers.

What is Pollination?

Transfer of pollen grains from the anther to stigma is known as pollination. It is found in gymnosperms and angiosperms. Basically, the pollination is of two types, self-pollination and cross pollination.

Self-Pollination:

When the transfer of pollen grains takes place from the anthers to the stigma of the same flower or of another flower of the same plant, it is called self-pollination.

Cross Pollination:

When the pollen grains from the anthers of a flower are transferred to the stigma of a flower borne on another plant, it is called cross pollina­tion.

Exercise 1:

To examine wide range of flowers avail­able in your locality to study methods of their pollination.

Requirements:

Wide range of flowers like Catharanthus roseus, potato, wheat, Commelina benghalensis, Bougainvillea, Nyctanthes, Cestrum, Callistemon, Anthocephalus cadamba, Chrysanthe­mum leucanthemum, maize, sugarcane, Vallisneria and Hydrilla, etc.

Observations:

(a) In Catharanthus roseus, Potato and Wheat:

In these plants, the stamens and carpels of a flower ma­ture at the same time. Due to this the pollen grains of a flower can pollinate the stigma of the same flower. These plants thus show self pollination.

(b) In Commelina benghalensis:

In this plant, flow­ers open after maturation and expose their stigma and anthers to the environment. Such flowers are called chasmogamous flowers. Some other flowers of this plant, however, do not open even at maturity and gen­erally remain underground. Such flowers are called cleistogamous flowers (Fig. 180).

In both chasmogamous and cleistogamous flowers of Commelina, the transfer of pollen grains takes place from the anthers to the stigma of the same flower, and, therefore, this is also an example of self pollination.

(c) In Bougainvillea:

Bright red or variously- coloured bracts of the flower of Bougainvillea attract insects, which transfer the pollen grains of one flower to the stigma of another flower, showing the example of cross pollination. Since it is affected by insects, this type of cross pollination is called entomophily.

(d) In Nyctanthes and Cestrum:

In Nyctanthes (Harsingar or Night Jasmine) and Cestrum nocturnum (Raat-Ki-Rani or Queen of Night), insects are attracted by the flowers due to their strong scent or odour. Since, insects transfer the pollen grains of one flower to the stigma of another flower, these plants show cross polli­nation and entomophily.

(e) In Callistemon:

In Callistemon (Bottle brush), transfer of pollen grains of one flower to the stigma of another flower is facilitated by crows, mynas and other birds. It is, therefore, a case of cross pollination by birds, i.e., ornithophily.

(f) In Anthocephalus cadamba:

In this plant, the pol­lination takes place by bats which visit several flowers to collect nectar. In this process of nectar collection, pollen grains of one flower are transferred to the stigma of another flower. It is, therefore, a case of cross polli­nation by bats, i.e., cheiropteriphily.

(g) In Chrysanthemum leucanthemum:

In this plant, pollen grains of one plant are transferred to stigma of another plant by snails and slugs. It thus shows an example of cross pollination by snails and slugs, i.e., malacophily.

(h) In Maize and Sugarcane:

In these plants, flowers are small-sized and not showy. They even lack any odour or smell. Large number of pollen grains produced by these plants are taken upto the stigma of the other flowers of same or another plants by wind. This is thus a case cross pollination by wind, i.e., anemophily.

(i) In Vallisneria and Hydrilla:

Transfer of pollen in these hydrophytic plants takes place through water. They thus show cross pollination by water, i.e., hydrophily.