Cross section:
I have removed two petals from this flower so you can see inside it.
When a pollinator enters the flower from one of the lateral portals, here is what probably happens.
The pollinator deposits pollen on the stigmatic surface (indicated with a letter "B").
Then, it crawls up to the anthers (indicated with a letter "A") for a nutritious, albeit somewhat dry meal of
pollen. Finally, it can leave by dropping straight down the flower--perhaps guided by the curling flower petals which
create a set of tunnels that keep the pollinator (now freshly dusted with pollen) far from the stigmatic surface.