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Old 09-19-2011, 03:45 AM   #1 (permalink)
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Default Why some plants fold up at Night.



EXAMPLE: Folded, UnFolding, UnFolded

Timelaps - YouTube

Left: Quick ------------------------------------------------------------------------- Right: Slower


--------------------------------------------------------------

I have been observing my wisteria (hygrophila difformis) fold
up and night and it sparked my curiosity. I dug in and wanted
to share my findings. It's quite interesting and seems to be
still in the research stage.

Basically it's called "Nyctinasty"

"The circadian rhythmic nastic movement of higher
plants in response to the onset of darkness."

--------------------------------------------------------------

My question is why would aquatic plants want or need to do this?
I understand at night there's no sunlight so no need to have a large area,
like their leaf open to collect light. Is it a defensive change to protect
their leaves at night? or is it just a left over trait from its terrestrial version,
A lot of our plants can grow out of water as well as in.

There is no defined reason why, but there are a few theories.

1) One being for flowers, they close at night to protect the pollen from
getting dew on it, but this doesn't explain the leaves.

2) Could be due to the fact that photosynthesis has stopped at night and
there is an lack of some sort of chemical movement which shrinks the cells
and cause them to fold.

3) Darwin suggested they close to protect from chilling or freezing.

4) Buning suggested they close to protect the photoperiodic time keeping
system from moonlight which could interfere with the plants ability to
accurately measure the length of night.

--------------------------------------------------------------

To continue the mystery, Nyctinastic plants seem to be on a biological timeclock,
even if you keep one in a completely dark room it will still open/close every 24 hrs.

--------------------------------------------------------------

References:

Really detailed studies on Chemical changes and leaf movement.
http://www.iupac.org/publications/pa.../7502x0353.pdf

Darwins study of movements of plants. (A Very LARGE .PDF open once and save it haha)
http://darwin-online.org.uk/pdf/1880_Movement_F1325.pdf

Flower opening and Closure
Flower opening and closure: a review


--------------------------------------------------------------


This Thread is now open to other theories, questions, and ideas!

Last edited by TheBigCheese; 09-20-2011 at 02:47 AM.
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Old 09-19-2011, 10:16 PM   #2 (permalink)
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Great picture taking. I gues it is just like us. We like to sleep with the lights off.
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Old 09-20-2011, 10:34 AM   #3 (permalink)
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nice video!! Was it done by video camera or just a number of picts?
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Old 09-20-2011, 12:39 PM   #4 (permalink)
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Like many biological phenomena, it could be that the behavior though obviously a product of evolution could be something that just happened or may have had a useful function but otherwise doesn't help or hinder the organism, like yawning. Mutations are random, natural selection is not.

I don't buy the folding up when they aren't "hungry" anymore because it doesn't take that much sunlight to photosynthesize and the entire plant, or all of its green bits can photosynthesize and photosynthesizing in low light doesn't cost the plant anymore resources as when in full sun.

Folding up to protect against grazers doesn't wash either because if it smells edible or is merely there, it's going to get eaten, nothing can stop that.

Protecting against frost would only make sense if plants could generate their own heat and I only know of one species that can do that and it is strictly for the purposes of being attractive to bees in early spring when it is still rather cold.

It's pretty cool and as accurate as a clock but I think the phenomena is like so much of the genetic detritus any organism picks up, again, not useful but not a hindrance either or vestigial as in it once did serve a function.

still, pretty cool pictures and the video is very nice.
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Old 09-20-2011, 12:47 PM   #5 (permalink)
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Here's my guess..
It's probably a combination of reasons.
Plants don't particularly need to have such a large surface area at night when there isn't photosynthesis taking place. Also, the temperature will probably drop slightly when the sun goes down, so keeping warmth close is probably a priority. Pair all that with the plants natural circadian rhythm, explains why some do it, even when there isn't any light.
If you read through the article where they are talking about the chemicals that control nyctinasty, it says that each plant species may have different chemicals, hormones, etc, that control this. I'd deduce that it's highly probable that some plants do it for different reasons than others. My Wallichii would open and close depending on whether the light was on or not, as would my Aromatica. Perhaps they do it simply because there is no use in keeping such a vital part of itself vulnerable when there is no light.
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Old 09-20-2011, 12:50 PM   #6 (permalink)
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ninja'd by Uka. C'est la vie
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Old 09-20-2011, 02:41 PM   #7 (permalink)
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Quote:
Originally Posted by gkpeter View Post
nice video!! Was it done by video camera or just a number of picts?
gkpeter
just used the time lapse setting on my wife's old digital camera.
I had to speed it up quite a bit more so you can actually see
the leaves moving.


Enjoyed reading others posts. I wanted to stir things up and see
what people thought or what ideas they had, makes for good discussions.

Carry on...
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Old 09-20-2011, 07:26 PM   #8 (permalink)
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What a great post TBC!!! I dont think anybody has done anything like this. Is this thread sticky worthy for some reason guys?
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Old 09-20-2011, 08:00 PM   #9 (permalink)
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Definitely as an FYI and for the excellent quality videos and pictures!
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Old 09-20-2011, 08:02 PM   #10 (permalink)
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Done. Its really cool and I have never seen a video like it, glad to see it surface on APE
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