Question

Angiosperm reproduction relies on animals, wind, gravity or secretion to convey pollen grains from the male to the female organ. However, researchers have studied one species of orchid that is entirely self-reliant for its reproduction. The orchid rotates its anther in order to insert pollen into its own stigma cavity then rotates the anther back, against gravity, to its original position. List 3 different physical features of the orchid that would be consistent with its complete dependence on self-fertilization. Explain the 3 choices.

Answer 1

The orchid has its filaments, anthers, style, and stigma reduced in number and it is fused into a single structure called column. There is a single anther at the top of the column: This makes it easy for the  anther to rotate and deposit pollen grains in the stigma. And because of having only one anther and reduced number of other parts, it has to rely on self pollination.

The sepels are joined and the petals are and sepels are joined to the column. The petal opposite the fertile stamen is called thelip. In orchids, the fertile stamen is opposite side of the lip and it makes it bilaterally symmetrical. The lip is oriented upwards in bud time, but when orchid develop, the ovary twists and lip is oriented downward. : This makes the anther to be on the top and when it is working along with the gravity and makes it easier to deposit pollen. The lip prevents the escape of pollens due to gravity to the outside. So, it has to rely on self-pollination.

The stigma is composed of three lobes but they are fused together and the pollen grains are bound together by threads of sticky substance called pollinia: This makes the pollen grains unable to escape to other flowers for pollination by external agents such as wind. The fusing of the lobes of the stigma makes sure the pollen grains are not escaped after getting them from the anther. So, they have to rely on self-pollination.