WARNING: There’s a high yuck factor to this post, it’s not for the squeamish or easily offended!
One of my Twitter contacts, Traci Birge in Finland, has been reading Pollinators & Pollination: Nature and Society, and making some very nice comments about it. I had to laugh at this one in which she describes some plants as “assholes” because of the way in which they deceive pollinators into visiting their flowers but offer no reward in return:
If you follow that thread you can see that Traci was closer to the truth than perhaps she realised: there are some plants with flowers that appear to mimic the anuses of dead mammals, particularly in the families Apocynaceae and Araceae. By their smell, texture, colour and hairiness they are fooling flies into visiting the flowers, because assholes, like any mammalian orifice, provide an entry point for maggots of carrion-feeding flies. Sometimes the deception is so great that the flies lay their eggs on these blooms, though of course the maggots starve.
A great example of an anus-mimicking bloom is the Dead Horse Arum (Helicodiceros muscivorus). Check out the image above: if that doesn’t look like a horse’s ass, I don’t know what does!
Other examples might be found within the stapeliads, especially the genus Huernia which often have a thickened annulus to the centre of the flower. However that could also be interpreted as mimicking an open, inflamed wound on the side of an animal:
As I point out in the book, you might imagine that there would be strong natural selection against flies visiting these flowers if they lose fitness by laying eggs on such an unsuitable substrate. But the flowers are tapping into really deep-seated behaviours and clearly the flies can’t distinguish the flowers from the real thing.
This is flower pollination that is far removed from the deliciously perfumed, cute-and-cuddly, heart-warming world of bees and flowers. Isn’t nature wonderful?
All photos from Wikipedia, as follows:
Helicodiceros muscivorus: Göteborgs botaniska trädgård (photographer: Ingemar Johansson) – http://www.mynewsdesk.com/se/pressroom/goteborgs_botaniska_tradgard/image/view/dracunculus-muscivorus-128973, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=19265330
Huernia zebrina: Enzo^ – Own work, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=10963668
Huernia schneideriana: Juan Carlos Fonseca Mata – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=94705877
Prof. Jeff Ollerton - ecological scientist and author 
Jeff:
The same thing may be occurring in some Corunastylis species. The chloropid pollinators are known locally as eye flies in Australia but if you look at the chloropid literature these insects may start at the anus before invading the eyes. I’m tempted to design a t- or sweatshirt that reads, “Chloropids drink MAGA tears.” Check out our reference section. Maybe it’s time we started defining those habitats or biomes in which floral evolution is highly driven by guilds of micro-dipterans.
And yes, things in America are pretty weird right now.
Peter
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Thanks Peter. Agreed, there’s some interesting patterns that have been over-looked amongst the micro-dipteran pollinated flowers.
Alan Moss is my last PhD student. Well, he was my PhD student until I retired in June 2019. Completion of his thesis was much delayed by the pandemic of 2020. I remain on his PhD committee and part of his fieldwork in Yunnan was funded by the Bernhardt/Edens-Meier Laboratory at Saint Louis U. You are most welcome to join Alan on Zoom if you can’t come to Saint Louis University (see title below). I will be introducing Alan. Remember, we have three time zones in continental America and Saint Louis Missouri is on Central Time. If you are suffering through another hot, muggy summer, you may enjoy an hour in the Himalayas (2700-3900M). Please ask Alan for the Zoom link using his email (also below) and do not share to avoid Zoom bombers.
Peter