 The general observation of insects being trapped and aiding pollination were made as early as 1872 by Thomas Frederic Cheeseman and did not go unnoticed by Charles Darwin who examined the adaptations of orchids for pollination.Slipper orchids have smooth landing surfaces that allow insects to slide into a container from which a window of light leads the insect outwards through a narrow passage where the pollen transfer occurs.The structures found in large flowers such as those of "Rafflesia" and some "Aristolochia" are also evolved to attract and trap pollinators.