Question

Explain the steps that ensure cross pollination in an autogamous flower.

Answer 1

Hint: When pollen grains are transferred from the anthers to the stigma of the same flower, it is called self-pollination. When pollen grains are transferred from the anthers of one flower to the stigma of another flower that are carried to different plants of the same or different species is called cross pollination.

Complete answer:
First of all before answering the question let’s understand what is pollination
Transfer of pollen grains from open anthers of flowers to the pistil is called pollination.
Autogamy or self pollination-When pollen grains are transferred from the anthers to the stigma of the same flower, it is called self-pollination.
Geitnogamy: The process of transferring pollen grains from one flower anther (same-sex or bisexual flower) to the pistil of another flower (same-sex or bisexual) that appears on the same plant is called geitonogamy.]
Xeno-gamy: It involves the transfer of pollen grains from the flower of one plant to the pistil of another plant. It is the only type of pollination that genetically stigmatizes different types of pollen during pollination, such as papaya, corn and others.
Self-pollination only occurs in bisexual flowers and is never unisexual. There are various devices that ensure self-pollination
Steps that ensure cross pollination in and self pollinating flowers:
Self-sterility: This is a condition in which a flower cannot be fertilized with the pollen of the same flower . In some orchids, when pollinated with pollen, the flowers wither. Many Solanum species (potatoes, tobacco, etc.) and tea plants are sterilized on their own for genetic reasons. These plants require cross-pollination.
Dichogamy: When the stamens and pistil of a benign flower ripen at different times, pollination between them becomes ineffective. However, it is sometimes found that if cross-pollination fails, self-pollination may occur later. There are two types of Dichogamy.
Protandry: Like most members of Asteraceae In many umbellates the anther matures first. As a result, when the anther is broken, it pollinates the stigma of other flowers instead of the stigma of its own flower.
Protogyny: Carpels of many Annonaceae and Magnoliaceae ripen first. Stigma relies on foreign pollen for pollination.
Herkogamy: In flowers of some families a physical barrier present between the anthers and the stigma. In orchids and members of the Asclepiadaceae such as Calotropis procera, where pollen is collected in pollinia, pollination is completely dependent on insects.

Note:
Advantages of cross pollination- Cross-pollination is useful for increasing crop yields and for producing new varieties of various crops such as fruits, vegetables and others. Offspring becomes healthier and stronger. Cross pollination increases the production of more viable seeds. Plants are better adapted to nature.
Pollination is uncertain because it depends on external locations such as wind, insects, water and many more. Pollen wastes much more because it depends on external agents. Pollen waste is more common in anemophily (wind pollination) than in other species.
Cross pollination can be achieved by various pollinating agents for example
Anemophily- Pollination by wind
Hydrophily-Pollination by water
Entomophily- Pollination by insects
Malacophily- slugs, snails and squirrels
Ornithophily- Pollination by birds
Chiropterophily Pollination by bat