Question

Which part of a flower receives pollen transported by the wind or a pollinating animal? a. perianth b. stigma c. filament d. pedicel e. ovary

Short answer

The part of a flower that receives pollen transported by the wind or a pollinating animal is b. stigma

Step-by-step solution

Understanding Flower Parts

Each part of the flower has its own role. The perianth is the non-reproductive part of the flower, and includes the petals and sepals. The filament is the stalk of the stamen and supports the anther, which produces pollen. The pedicel is the flower's stalk. Lastly, the ovary is the part of the flower that after fertilization develops into a fruit that contains seeds.

Identifying the Correct Part

The part that receives pollen transported by the wind or a pollinating animal is the female part of the flower. This part must be sticky or shaped in a way to catch and trap pollen. Comparing the functions of parts given in the options, the stigma is the part of the flower which receives and traps the pollen. In many flowers, the stigma is sticky to effectively trap pollen. It is the receptive tip of a carpel which may also be on the end of a stalk (the style).

Key concepts

Stigma Function

The stigma plays a crucial role in the reproductive process of flowering plants. Its primary purpose is to receive pollen grains during pollination. When pollen from a compatible flower's anther lands on the stigma, a remarkable process unfolds. The stigma, often sticky or feathery in texture, ensures that the pollen grains adhere to its surface. This adhesion is critical for successful pollination and subsequent fertilization.

Once the pollen makes contact, the stigma facilitates the germination of pollen grains. This triggers the growth of pollen tubes, which navigate through the style – a slender stalk connecting the stigma to the ovary. The journey of the pollen tube is a critical step, as it carries sperm cells from the pollen grain to the ovule within the ovary. The end goal of this travel is the union of male (from pollen) and female (ovule) gametes, which results in the formation of seeds that may eventually grow into new plants.

It's important to note that while stigmas are adapted to trap pollen, they are also often selective, allowing only pollen of the correct species to germinate. This specificity prevents cross-pollination between incompatible plant species and ensures genetic consistency.

Flower Reproductive Parts

Flowering plants, also known as angiosperms, have evolved a complex structure for reproduction that involves various parts, each with a specific function. The main reproductive parts of a flower are contained within the male and female structures: the stamen and the carpel.

The stamen is the male reproductive part and comprises two main components - the filament and the anther.

• The filament is the stalk that elevates the anther into a position where it can disperse pollen.
• The anther, situated on top of the filament, is responsible for the production and release of pollen, which contains the male gametes.

The carpel, or pistil, is the female reproductive part consisting of three main sections:

• The ovary, which contains one or more ovules. After fertilization, the ovary will develop into a fruit enclosing the seeds.
• The style, which elevates the stigma and acts as a channel for pollen tubes to reach the ovary.
• The stigma, as previously discussed, is where the pollen is received.

These reproductive parts work synergistically to facilitate the process of sexual reproduction in plants, ensuring the transfer of genetic material from one generation to the next.

Pollination Mechanisms

Pollination is a fascinating biological process and a vital mechanism in the life cycle of flowering plants. It involves the transfer of pollen grains from the anther of a flower to the stigma of the same or another flower.

There are various mechanisms of pollination, characterized by how the pollen is transported:

Wind Pollination

Pollen grains are lightweight and can be transported by wind currents in plants like grasses and many trees. These plants generally have small, inconspicuous flowers with stigmas that are well adapted to capture the wind-borne pollen.

Animal Pollination

Animals, like bees, butterflies, birds, and bats, can be pollinators, transferring pollen as they move from flower to flower in search of nectar or pollen, a food source. Flowers that rely on animal pollinators are often brightly colored, fragrant, and contain nectar to attract these animals.

Self-Pollination

Some plants are capable of self-pollination when pollen from the anther falls directly onto the stigma of the same flower, or another flower on the same plant. This mechanism ensures reproductive success when no external pollinators are present.

Each pollination mechanism has its own adaptations and significance in helping plants to reproduce. A deeper understanding of these mechanisms not only fosters an appreciation for the complexity of nature but also highlights the importance of conserving pollinator species that many plants rely on for survival.