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What is the condition that prevents self-pollination because the flowers have to be large, scented, and produce nectar?
What is the condition that prevents self-pollination because the flowers have to be large, scented, and produce nectar?
Cross-pollination
In some flowers, the pollen of a flower cannot reach the stigma of the same flower due to a mechanical barrier, such as a hood covering the stigma in flowers of Pansy; ___, etc.
In some flowers, the pollen of a flower cannot reach the stigma of the same flower due to a mechanical barrier, such as a hood covering the stigma in flowers of Pansy; ___, etc.
Iris
What are some characteristics of wind-pollinated flowers? (Select all that apply)
What are some characteristics of wind-pollinated flowers? (Select all that apply)
Artificial pollination is a standard practice adopted by plant breeders and scientists to evolve new plant varieties.
Artificial pollination is a standard practice adopted by plant breeders and scientists to evolve new plant varieties.
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In wind-pollinated maize, pollination is primarily brought about by _________.
In wind-pollinated maize, pollination is primarily brought about by _________.
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What is the primary purpose of the feathery stigmas of female flowers in wind-pollinated maize?
What is the primary purpose of the feathery stigmas of female flowers in wind-pollinated maize?
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Which floral part is responsible for transferring the pollen grain to the stigma in sweet pea flowers?
Which floral part is responsible for transferring the pollen grain to the stigma in sweet pea flowers?
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What is pollination?
What is pollination?
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Which of the following are ways in which pollination can occur?
Which of the following are ways in which pollination can occur?
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What is self-pollination?
What is self-pollination?
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What is cross-pollination?
What is cross-pollination?
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Which of the following are advantages of self-pollination?
Which of the following are advantages of self-pollination?
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Study Notes
Pollination
- Pollination is the transfer of pollen grains from the anther to the stigma of a flower.
- There are two types of pollination: self-pollination and cross-pollination.
Self-Pollination
- Self-pollination is the transfer of pollen grains from the anther to the stigma of the same flower.
- It can occur in bisexual flowers or in unisexual flowers where both male and female flowers are borne on the same plant.
- Advantages of self-pollination:
- It is a surer process in bisexual flowers where stamens and carpels mature at the same time.
- Parental characters are preserved.
- There is no wastage of pollen grains.
- The flowers need not be large and showy.
- Disadvantages of self-pollination:
- Continued self-pollination may lead to weakening of the variety or species.
- The seeds produced are poor in quality and give less vigorous offspring.
- It does not yield new varieties.
Cross-Pollination
- Cross-pollination is the transfer of pollen grains from the anther of one flower to the stigma of another flower of the same species.
- Advantages of cross-pollination:
- The offspring are healthier.
- The seeds produced are abundant.
- New varieties may be produced by cross-pollination.
- Disadvantages of cross-pollination:
- It requires an external agent (wind, water, insect) to be present.
- The pollinating agent may not be available at the right time.
- The pollen quantity may not be sufficient.
Agents of Cross-Pollination
- Insects: insects like bees and butterflies are common agents of cross-pollination.
- Wind: wind is another common agent of cross-pollination.
- Water: water-pollinated flowers are found in aquatic plants.
- Birds: some flowers are pollinated by birds.
Characteristics of Insect-Pollinated Flowers
- They have bright colors to attract insects.
- They produce nectar, which is food for insects.
- The pollen grains are sticky or spiny to enable them to be carried by insects.
- The stigma is often hidden and does not generally hang out of the flower.
Characteristics of Wind-Pollinated Flowers
- They are usually not brightly colored.
- They produce a large amount of pollen.
- The anthers are often versatile and loosely attached to the filaments.
- The pollen grains are light and smooth.
- The stigmas are often hairy and rough to trap the pollen grains.
Fertilization
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Fertilization occurs when a pollen grain reaches the stigma and germinates, producing a pollen tube.
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The pollen tube grows down through the style and into the ovary, where it fertilizes an egg cell.
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The fertilized egg cell develops into a zygote, which then grows into a seed.
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The process of fertilization is essential for the reproduction of flowering plants.### Differences between Wind-Pollinated and Insect-Pollinated Flowers
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Wind-pollinated flowers have dull colors, no fragrance, and produce large amounts of pollen grains that are light, smooth, and small.
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Insect-pollinated flowers are brightly colored, fragrant, and secrete nectar, with fewer pollen grains produced that are larger, sticky, and spiny.
Characteristics of Wind-Pollinated Flowers
- Unisexual flowers
- Stigma is long and hangs out of the petals
- Stamens are long and protrude above petals
- Examples: Maize, grass, rice, wheat, China rose, Salvia, pea, sunflower
Characteristics of Insect-Pollinated Flowers
- Stigma is often deep in the corolla and small
- Stamens may be within the corolla tube
- Examples: Sweet pea, flowers that require pollination by insects
Elephophily
- Elephophily is a type of pollination involving elephants
- Found in Rafflesia, a rare flower that grows at the feet of elephants
- Pollen grains get stuck to the elephant's feet and are carried to other similar flowers
Artificial Pollination
- Artificial pollination is the transfer of pollen to the stigma by humans
- Practiced by plant breeders and scientists to evolve new varieties
- Involves emasculation (removing anthers) and bagging (covering flowers with plastic bags)
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Description
This quiz is about a condition in plants where the pollen from the same flower fails to fertilize the stigma, despite the presence of pollinating agents.
