Species of the Australian terrestrial orchid genus Pterostylis
(Greenhod-Orchid) actually trap pollinating insects by a trap-door
mechanism.
A good (although old) source of information about the many strange
pollination phenomena in Orchidaceae is van der Pijl and Dodson 1966:
Orchid flowers, their pollination and evolution, University of Miami
Press.
Finn R
Finn N. Rasmussen
Botanical Laboratory, University of Copenhagen
Gothersgade 140, DK-1123 Copenhagen K., Denmark
Phone: +45 35 32 21 55 Fax: +45 33 13 91 04
Web homepage: http://www.bot.ku.dk
Email: FinnR@bot.ku.dk