Question

Many flowers have brightly colored petals and some have an odor, how does this function in fertilization?

Answer 1

Fertilization is the fusion of male and female gametes. Fertilization is the root of genetic variation, gamete formation and above all, the continuity of the species. In flowering plants (i.e., Angiosperms), both the gametes (male and female) are non-motile. During the time of fertilization, there should occur physical contact between the two gametes, which can occur only if any one of the gamete is transferred to the place where the other gamete is located. It is the male gamete that reaches the female gamete with the help of some agents. The gamete transfer in angiosperms is called pollination. Pollination is the transfer of pollen grains (Micro gametophyte - can produce male gamete) to the stigma (receptor of female reproductive system of flowering plants). Later, the male gametes move to the ovary through the style. Hence, in angiosperms, it is not the gamete, but it is the micro gametophyte (or male gametophyte) that is transferred to the female reproductive part.

In self pollinated plants (pollination within a plant), there is no need for an agent to aid pollination. The structural make up of flowers aids in self pollination for those plants. But, in the case of cross pollinated plants (pollination between plants) , it is essential that an agency should assist in pollination between two plants. The agent involved in pollination is called pollinating agent. The pollinating agent can be wind, water, insects, mammals etc. There will be one or more specific pollinating agents for a particular plant species. This is because, the morphology of the flowers are designed in such a manner that it favours a particular agent. For example, in wind pollinated (anemophilous) plants like Maize (also called Corn ) the stigma is hairy so that it assists in capture of the pollengrains flowing with the wind. Similarly, the insect pollinated plants (entomophilous) also have several morphological adaptations. The morphological adaptations in entomophilous plants are mostly to attract the insects to the flower. Insects are more attracted to flowers with bright coloured petals, odour or scent, nectar etc. As a result, plants with such features attract more, but specific insects, thus favouring pollination by insects.

This is how the bright colour of petal and the odour of flowers function in fertilization.