A flower that does not have a stalk and is directly attached to the stem is called a sessile flower.
Definitions [6]
Define.
Inflorescence
A specialised axis or branch over which flowers are produced or borne in definite manner is known as inflorescence.
Definition: Pedicellate Flower
A flower that has a stalk called pedicel for support is called a pedicellate flower.
Definition: Bisexual Flower
A flower that has both androecium (male part) and gynoecium (female part) in the same flower is called a bisexual flower.
Example: Hibiscus
Definition: Sessile Flower
Definition: Unisexual Flower
A flower that has only one reproductive whorl (either androecium or gynoecium) is called a unisexual flower.
- If it has only androecium: male flower
- If it has only gynoecium: female flower
Example: Papaya
Definition: Pollination
Transfer of pollen grains from the anther to the stigma of a flower is called pollination.
or
Pollination is the transfer of pollen grains from the anther of a flower to the stigma of the same flower or of another flower of usually the same species.
Key Points
Key Points: Sexual Reproduction in Plants
- Sexual reproduction involves the fusion of male and female gametes from two parents to form a diploid zygote.
- A flower is the reproductive structure in plants that produces gametes and enables fertilisation.
- A flower has four whorls: calyx, corolla, androecium (male), and gynoecium (female).
- It includes meiosis for gamete formation and fertilisation, producing genetically different offspring.
- Sexual reproduction occurs in three stages: pre-fertilisation, fertilisation, and post-fertilisation.
Agencies of Pollination
| Agency | Agent | Type | Examples |
|---|---|---|---|
| Anemophily | Wind | Abiotic | Wheat, rice, maize, grass |
| Hydrophily (Hypo) | Water (submerged) | Abiotic | Zostera |
| Hydrophily (Epi) | Water (surface) | Abiotic | Vallisneria |
| Entomophily | Insects (e.g., bumblebee) | Biotic | Rose, Jasmine, Salvia, Lotus |
| Ornithophily | Birds (e.g., sunbird) | Biotic | Bombax, Butea, Callistemon |
| Chiropterophily | Bats | Biotic | Anthocephalus, Kigelia, Adansonia |
Key Points: Pollination
- Pollination is the transfer of pollen grains from anther to stigma and is essential for fertilisation since gametes are non-motile.
- Pollination occurs through external agents such as wind, water, and animals because pollen grains cannot move on their own.
- There are three types of pollination: autogamy (same flower), geitonogamy (same plant), and xenogamy (different plants of the same species).
- Self-pollination leads to inbreeding, while cross-pollination increases genetic variation.
- Abiotic agents of pollination include wind (anemophily) and water (hydrophily).
- Biotic agents include insects, birds, and bats, which help in effective pollen transfer between flowers.
