Orthochilus aculeatus subsp. huttonii resupinating

Newly opening Orthochilus aculeatus subsp. huttonii buds do a gradual twist through 180° that takes their lips from the top of the flower to the bottom, below the vital parts in the central, floral column.

The process is called resupination. Orchid flowers have their lips at the top in the tiny beginner buds. Resupinated orchids position their flowers' lips conveniently for pollinator landing. These platforms serve the pollinators for reaching the food provided they came for, and simultaneously touching the parts involving pollen transfer. So, the lips are equipped with species unique visual, colour and shape clues ensuring the most precise pollen transfer in an uncertain world.

In picture, the buds at the top still have to twist, some below them are partly done, while the lowermost open flower is fully resupinated. Pollinators land on resupinated lips, finding the male parts in the column from which pollen is obtained once it is ripe, and depositing the pollen stuck to their bodies, and which they did not eat, onto female flower parts in the columns of more flowers visited subsequently.

The idea of flowers of a species having a particular look and feel fits the need for the next flowers visited by the still hungry insect to be of the same species. Foreign pollen won't grow. If you like what you tasted, here are more morsels from the same kitchen. Come along without wiping your mouth, feet and whatever!

Only some orchids are resupinate. The flower structure of resupinated species yield better pollination results deformed or enhanced like this, so the resupination solution became the norm for them. This leaves non-complying flowering specimens of their kind dying prematurely, unfertilised, no seed set. Uncle Darwin's stories are still true enough but today there's more. In the meantime, orchid species retaining non-resupinating flower structures perform just fine with older pollination arrangements, no need for the offspring-yielding twist. 

That is the general system, give or take specific peculiarities. Functional and non-functional deviations happen in flowers as in life, some insects getting fed and some orchids getting pollinated. As long as the pollination statistics for your species are favourable, your kind and your pollinators stay extant, other factors remaining unchanged (Germishuizen and Clarke, 2003; Pooley, 1998; iNaturalist; https://www.orchidspecies.com).