Flowers adapted to pollination by different agencies (wind, insects, birds)

Aim: Flowers adapted to pollination by different agencies (wind, insects, birds)

Theory:

1. The process of transfer of pollen grains from anther to the stigma of either the same flower or another flower of the same species is called pollination.

2. Pollen grains are immobile, hence require external agencies to reach to the stigma.

3. The external agencies involved in pollination may be abiotic (wind and water) or biotic (insects, birds and snail)

Material/Apparatus Required:

• Fresh flowers
• Magnifying glass
• Glass slide

Procedure:

Place the given slide on a slide and observe it with the help of hand lens. Note down the adaptation of the flowers meant for pollination by the external agencies.

Maize Flower (Anemophilous or wind pollination flowers)

The flower of maize shows following adaptations for pollination by wind.

1. The maize plant is monoecious and bears unisexual flowers. The male flowers are born in terminal inflorescence while the female flowers are born in axillary inflorescence.
2. Flower is small, colorless, odourless and nectarless.
3. Flowers are placed in hanging position.
4. Anther and stigma both are exerted (i.e., hang outside the perianth).
5. Anther are versatile, and pollen grains are light, small and dusty.
6. The pollen grains are produced in very large numbers.

Salvia Flowers (Entomophilous or Insect pollinated flowers)

The flowers of saliva show following adaptation for pollination by insects.

1. The flower is showy or brightly colored for attracting pollinating insects.
2. Flowers secrete nectar to feed visiting insects. Nectar glands are placed in such position that an insect must touch both anther and stigmas.
3. The flower has landing platform for the insects.
4. Flowers have distinct smell to attract the insects.
5. As the insect move inward a young flower in search of nectar, its head pushes, the anther plate and force the sterile anther lobe to strike against its back.
6. In older flowers the style brings the stigma in such position that it brushes against the back of the insect and collect pollen gains bought by the insect from a young flower.

Bignonia/ Callistemon (bottle brush) flowers (Ornithophilous or bird pollinated flowers)

The flowers of Bignonia show following adaptation for pollination by birds.

1. The flowers are usually brightly coloured-red, orange, yellow or blue.
2. The floral parts are commonly leathery.
3. In some cases, the corolla is leathery.
4. The flowers secrete abundant watery nectar or have edible parts.
5. The nectar is secreted in such abundance that drop of it can be brought down by shaking branches.
6. The flowers are generally odorless or without fragrance.