Some orchids produce two types of flowers, one with only anthers and the other with only carpels. And on some orchids like this, the flowers look very different from on another. An explanation for this difference is

The Orchids is the diversified structures of flowers, in fact, they have unique feature. Even with the pollination, they have several mechanisms of pollination. Few of them include:  

1. Few orchids have self-fertilization where the anther converts from solid-state to a liquid state without any aid of an external pollinating agent.  

2. In others, self-pollination occurs, when the caudicles dry the pollen fall on the stigma.  

3. This happens through an external pollinator resulting in a diversity of species.  

4. This is a very special case where the flower attracts the insect to mate with bright petals, odor, and the shape.  

5. These types depend on ants and other insects to get pollinated.

6. Here, the pollens release some kind of force, when an insect gets in contact with anther which results in getting away the agent from the flower.