Answer:
Pollination and Fertilization
Plants can transfer pollen through self-pollination; however, the preferred method is cross-pollination, which maintains genetic diversity.
Explanation:
Pollination, the transfer of pollen from flower-to-flower in angiosperms or cone -to-cone in gymnosperms, takes place through self-pollination or cross-pollination.
Cross-pollination is the most advantageous of the two types of pollination since it provides species with greater genetic diversity.
Maturation of pollen and ovaries at different times and heterostyly are methods plants have developed to avoid self-pollination.
The placement of male and female flowers on separate plants or different parts of the plant are also barriers to self-pollination.
Key Terms
pollination: the transfer of pollen from an anther to a stigma that is carried out by insects, birds, bats, and the wind
heterostyly: the condition of having unequal male (anther) and female (stigma) reproductive organs
cross-pollination: fertilization by the transfer of pollen from an anther of one plant to a stigma of another
self-pollination: pollination of a flower by its own pollen in a flower that has both stamens and a pistil.
Pollination: An Introduction
In angiosperms, pollination is defined as the placement or transfer of pollen from the anther to the stigma of the same or a different flower. In gymnosperms, pollination involves pollen transfer from the male cone to the female cone. Upon transfer, the pollen germinates to form the pollen tube and the sperm that fertilize the egg.
Self-Pollination and Cross-Pollination
Pollination takes two forms: self-pollination and cross-pollination. Self-pollination occurs when the pollen from the anther is deposited on the stigma of the same flower or another flower on the same plant. Cross-pollination is the transfer of pollen from the anther of one flower to the stigma of another flower on a different individual of the same species. Self-pollination occurs in flowers where the stamen and carpel mature at the same time and are positioned so that the pollen can land on the flower’s stigma. This method of pollination does not require an investment from the plant to provide nectar and pollen as food for pollinators. These types of pollination have been studied since the time of Gregor Mendel. Mendel successfully carried out self-pollination and cross-pollination in garden peas while studying how characteristics were passed on from one generation to the next. Today’s crops are a result of plant breeding, which employs artificial selection to produce the present-day cultivars. An example is modern corn, which is a result of thousands of years of breeding that began with its ancestor, teosinte. The teosinte that the ancient Mesoamericans originally began cultivating had tiny seeds, vastly different from today’s relatively giant ears of corn. Interestingly, though these two plants appear to be entirely different, the genetic difference between them is minuscule.
