Sunflower blossoms are suitable for insect pollination because crowding of flowers ensures notoriety and pollination of a maximum number of flowers by a single insect visit. The honey, secreted in the base of the style, is protected by the tube of the corolla of insects of short tongue. When the flower opens, the receptive surfaces of the two stigmas are pressed together and occupy a position at the base of the tube formed by the joined anthers; The latter is divided into the interior and the released pollen fills the cavity of the tube and exposes it to contact with the visiting insects. Fianll, the style protrudes through the anther tube and the stigmas separate and expose their previously concealed receptive surfaces. Thus, the life story of the flower falls into two stages, the first male and the second female. This favors cross-pollination compared to self-pollination. Therefore, the sun flower is virtually self-sterile, although self-pollination may take place at a late stage when cross-pollination has failed.
Pollination in legumes:
Pollination: As flowers are protandrosas, cross-pollination usually occurs. In Lathyrus and Pisum
pollination.
The mechanism of pollination in Fabaceae is 'piston mechanism'.
The type of pollination is entomophilia.
Insects are attracted to the standard petal.
They go down on the wing petals and press them down in search of the nectar collected in the resistance
Because of this, the keel petals are also pressed down and opened by exposing stigma and stamens.
The stigma that comes out first, is brushed to the abdomen of the insect and collects the pollen.
When the anthers come in contact with the insect, the pollen is deposited in your body.
As the insect leaves the flower, the essential organs return to their normal position.
Since the movement of essential organs is like that of a piston, it is called "piston mechanism".