Charles Darwin,
The Various Contrivances by which Orchids are Fertilised by Insects
(1877)
“ But as the column of Spiranthes after a time moves from the labellum, leaving a free passage for the introduction of the pollinia, so here the rostellum moves backwards, and not only recovers its former arched position, but stands upright, leaving the stigmatic surface, now rendered more adhesive, perfectly free for pollen to be left on it. The pollen-masses, when once cemented to an insect's forehead, will remain attached to it, until they are brought into contact with the stigma of a mature flower ”
