This question has been rolling around inside my head since I started my Hoya Collection.

Why do some hoya's have petals that reflex and others do not? Personally, I don't find reflexed hoya blooms very pretty. Some of the most gorgeous foliage plants have blooms that reflex, so I do collect them. Is there a biological advantage to this action?

With reflexed flowers, maybe theres a better chance a critter will polinate, but less chance said critter will locate the flower? And visa versa, nonteflexed flowers said critter will locate but less chance of pollination because of the larger surface area?