Rapid plant movement in Cacti

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Carbo
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Joined: Fri Feb 01, 2019 4:22 pm
Location: Serbia, Belgrade

Rapid plant movement in Cacti

Post by Carbo »

When this opuntia's (most likely stricta) flower is disturbed, it rapidly pulls all disturbed anthers towards the pistil and in the process self-pollinates. I just noticed this today and I'm amazed, what could possibly be the reason for it to do this? Normally cacti avoid self-pollination/fertilization. Anthers return to their normal position once the flowers is left alone.

https://i.imgur.com/SHGe2E3.mp4

Edit: My theory, when any insect land on the flower, it starts crawling down to get to nectar. Meanwhile the anthers all close up like in my video, so now when it crawls back up, it will get coated in a lot of pollen.
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One Windowsill
Posts: 544
Joined: Mon Sep 12, 2011 5:27 pm
Location: Manchester

Re: Rapid plant movement in Cacti

Post by One Windowsill »

I would say your theory is probably correct.

It is an example of thigmonasty, various plant responses to touch. Many cactus flowers have this, including Notocactus, opuntioids (Opuntia and Puna, definitely), Pediocactus and Pterocactus.

Here are some videos:

https://www.youtube.com/watch?v=cag90Fp6bgs

https://www.youtube.com/watch?v=Hd1Ci2NC-FY

https://www.youtube.com/watch?v=FjV--NPPjlU

https://www.youtube.com/watch?v=TzkQ2NxLpec
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Carbo
Posts: 95
Joined: Fri Feb 01, 2019 4:22 pm
Location: Serbia, Belgrade

Re: Rapid plant movement in Cacti

Post by Carbo »

One Windowsill wrote: Sun Jun 13, 2021 12:23 pm I would say your theory is probably correct.

It is an example of thigmonasty, various plant responses to touch. Many cactus flowers have this, including Notocactus, opuntioids (Opuntia and Puna, definitely), Pediocactus and Pterocactus.

Here are some videos:

https://www.youtube.com/watch?v=cag90Fp6bgs

https://www.youtube.com/watch?v=Hd1Ci2NC-FY

https://www.youtube.com/watch?v=FjV--NPPjlU

https://www.youtube.com/watch?v=TzkQ2NxLpec
How awesome, just when you think you can't possibly love cacti more than you already do, they prove you wrong :)
DaveW
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Joined: Thu Dec 20, 2012 2:36 pm
Location: Nottingham, England/UK

Re: Rapid plant movement in Cacti

Post by DaveW »

As you say it is usually to coat the nectar drinking insect in pollen in order to carry it to pollinate the next flower. In many flowers the stigma is only receptive before its own pollen sacks burst in order to prevent self pollination, or in self fertile plants to delay self pollination so it can outcross with another plant if possible? If it was in order to self pollinate it would move the anthers in to the stigma automatically rather than needing the stimulus of an insect to cause the movement?

See also:-

https://awkwardbotany.com/2015/06/10/ye ... kly-pears/

https://www.britannica.com/science/poll ... ationfirst
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