Pollination

Pollination

The process by which pollen is transferred from the anther to the stigma in the reproduction of plants.

Strategies to avoid self pollination

1. Herkogamy: flower have mechanical barriers of their stigmatic surface to avoid self pollination.

2. Dioecism: having male and female flowers on separate plants.

3. Heterostyly: flowers of the same flower have different lengths of stamens and style.

4. Dichogamy: maturation of stamens and carpels at different times.

5. Chemical barriers and self-incompatibility.

Agents of pollination

1. Biotic pollination: pollinators. Cross pollination depends on insects visiting flowers of the same species in sequence. Entomophily.

2. Abiotic pollination: pollination without the involvement of other living organisms. Wind (anemophily). Water (hydrophily)

Anemophily

Dominant in temperate deciduous forests and grasslands.

Deciduous trees: flowers appear before the leaves. Infloresence occur at end of branches. Perianth parts reduced exposing reproductive parts.

1. Staminate: pollen grains light, smooth surface. Large anther. Long and flexible filaments.

2. Carpellate: but stigmas separate expanded along upper surface of style.

3. Stigmatic: pollen receptive area, extending along upper surface of style thereby increasing the surface area.

Characteristics of the graminoids

Herbaceous plants. Exposed infloresences usually terminally situated. Perianth parts reduced, modified or very specialized. Flowers small and numerous. Male and female flowers separate

Characteristics of Poaceae

Stigmas extending out from leaves. Protecting the female infloresence. Exposed floral parts. Produce large quantities of pollen. Spikelets that are packed together.

Entomophily flower modification

1. Capitalization.

2. Nectar guides: lines that guide the bee to the nectar source, ultraviolet.

3. Nectar spur: hollow, slender, sac like projection of a floral parts, usually a petal or sepals.

4. Nectary discs: Nectar producing tissue on inner surface of the hypanthium

5. Pollinium: mass of pollen grains transported as a unit

6. Trigger flower: flower with one or more moveable parts, that cause the pollen to be forcibly deposited on the pollinator.

7. Landing platforms: flower buds developed immediately below leaf. The leaf is sturdy and supports the flower.

Beetle pollination

Cantharophily.

Have poor vision. Are day active.

Flowers: relatively large or grouped into large infloresence. Are light colored. Are smelly (fruity or spicy).

Been pollination

Melittophily.

Have good eyesight. Have a good sense of smell. Are day active.

Flower: colorful (not red). Having landing platform. Have a fragrance. Offer visitors Nectar, pollen or both. May have nectar guides.

Butterfly pollination

Psychophily.

Have good vision. Have long coiled tongue (proboscis). Must land on flower to visit it, cant hover. Are mostly Nectar feeders. Are day active.

Flower: colour varies (blue, yellow, orange). Have a landing platform. Have Nectar at bottom of floral tube.

Moth pollination

Phalaenophily.

Nocturnal. Have long tongue. Are mostly Nectar feeders.

Flower: colour varies (pale, dull). Have Nectar at bottom of floral tube.

Fly pollination

Flower color, brown or fleshy color. Scent rotten meat. No reward. May lay eggs but will fail to develop as their are no food.

Birds pollination

Ornithophily.

Long beaked. See red colors well. Are poor smellers. Can hover. Are day active.

Flower: red or orange. Have Nectar hidden by long floral tube. Have little or no fragrance.

Biotically vs wind

1. Biotically: petals large bright. Flowers often scented. Anthers and stigma inside flowers, stigmas sticky. Pollen in smaller quantities, often packaged, sticky. Provide rewards: nectar, pollen, oil.

2. Wind: petal small/absent. No scent. Anthers and stigma exposed, stigma feathery. Pollen in very large quantities, light and smooth. No rewards.