CROSS POLLINATION
SELF POLLINATION
The transfer of pollen between one plant’s anther and another plant’s stigma of the same species.
The transfer of pollen from the anther to the stigma of either the same flower or another flower found on the same plant.
HOW DO POLLEN GRAINS TRAVEL?
BIOTIC VECTORS
DEFINITION:
The moving of pollen grains by living organisms
EXAMPLES:
- Insects
- Birds
- Bats
- Additional Mammals
INFORMATION:
Over 80% of pollination is due to the transferring of pollen grains by insects, birds, and additional mammals. Remember, this means that they are also responsible for creating the ingredients used during the processing and manufacturing of the food we eat.
Since the biotic organisms above are responsible for so much of the food we eat, we dedicated an entire page to them! Read up about why we think pollinators are awesome, learn about this issues they face, and what we can do to increase their numbers in the Metro Atlanta area through GAPP!
ABIOTIC VECTORS
DEFINITION:
The moving of pollen grains by non-living factors
EXAMPLES:
- Wind(Anemophily)
- Water(Hydrophily)
INFORMATION:
As with any dispersal method, there are scenario’s that either promote successful dispersal or hinder it. For wind-pollinated species, the success of pollination relies heavily on the plants’ surroundings.
The ideal environment would be one in which plants are found in wide, open areas where pollen can be carried long distances easily and without obstruction.
However, imagine an environment with thick, dense canopies that would cause the obstruction of pollen flow, high amounts of water vapor that reduce the amount of pollen in the air, and high levels of plant diversity that would decrease the probability of successful cross pollination.
This type of environment can be found in rain forests and you may think that wind pollination is beginning to seem rather inefficient compared to biotic vectors. There are, however, adaptations by wind pollinated species that increase the likelihood of success. Read about these adaptations below!
WIND POLLINATED SPECIES ADAPTATIONS
Adaptation: Most wind-pollinated species share the common adaptation of producing high volumes of pollen.
Why is it Helpful? The reason for a higher chance of pollination and therefore fertilization is that the flower is producing much higher amounts of pollen than the ovules in which they are targeting.
Adaptation: Some wind-pollinated plants have evolved large stigma. Remember, this is the part of the plant the receives the pollen!
Why is it Helpful?: With a bigger stigma, there is a larger area that can “catch” the pollen being dispersed by the wind. Some plants have even developed feathery or broom-like stigmas to further aid in the success of fertilization!
Adaptation: Oftentimes, wind-pollinated species lack the corolla(the structure of the petals) and calyx(the sepals at the base of the flower). Together, these are known as the “showy” parts of the plant that typically are used to attract biotic dispersal vectors.
Why is it Helpful?: Without the corolla in the way, the stigma is more likely to be unobstructed, allowing for the easier pick up of pollen.
Adaptation: Some wind-pollinated plants have the drooped structures called catkins which almost always have no petals. These structures develop predominantly as a male flower, such as hazel or oaks but can also form in female species like poplar.
Why is it Helpful?: The male pollen producing catkins can hang down, away from the rest of the plant, and produce a large amount of unobstructed pollen for dispersal. As a female catkin, little to no petals will interfere with pollen drift and catkin droop would lead to an easier “catch.”