Comparison of Wind and Insect Pollinated Flowers

This page contrasts the characteristics of wind-pollinated and insect-pollinated flowers, providing detailed diagrams for each type.

Wind-pollinated flowers typically have: • Small, inconspicuous, or absent petals • No scent or nectar • Anthers hanging outside the flower • Large, feathery stigmas outside the flower • Large quantities of smooth pollen • Larger pollen grains

Insect-pollinated flowers usually feature: • Colorful petals, sometimes with nectar guides • Scent and nectar (mainly sucrose) • Anthers within the flower • Stigma within the flower • Small quantities of sticky, sculptured pollen • Smaller pollen grains

Example: A typical wind-pollinated flower might be a grass species, while a rose is a classic example of an insect-pollinated flower.

The page explains the process of cross-pollination in insect-pollinated flowers, detailing how pollinators like bees transfer pollen between flowers. It also describes how wind-pollinated flowers are adapted for pollen dispersal by wind.

Highlight: The adaptations of flowers to their specific pollination method demonstrate the intricate relationship between plant structure and reproductive strategy.

Ovule Development in Flowering Plants

This page explains the development process of ovules within the ovary of a flower, highlighting the roles of mitosis and meiosis.

Key steps in ovule development:

1. The ovary contains one or more ovules.
2. In each ovule, a megaspore mother cell undergoes meiosis.
3. This process produces four haploid megaspores.
4. Three of these megaspores disintegrate.
5. The remaining megaspore undergoes three rounds of mitosis.
6. This results in eight haploid nuclei within the embryo sac.
7. One of these nuclei becomes the female gamete.

Vocabulary: Nucellus - A layer of cells surrounding the embryo sac in the ovule.

Highlight: The complex process of ovule development ensures the production of a viable female gamete for plant reproduction.

The page emphasizes that these nuclei are contained within the embryo sac, which is surrounded by the nucellus. This structure is crucial for the eventual fertilization and seed development process.

Definition: Embryo sac - The female gametophyte of flowering plants, typically containing eight nuclei including the egg cell.

Understanding the development of both pollen and ovules is essential for comprehending the complete reproductive cycle of flowering plants.