sundewman
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Happy Growing!
Posts: 235
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Post by sundewman on Feb 19, 2011 17:41:33 GMT
Hi everyone, I've been searching to no avail as to the mechanism behind Nepenthes pitcher inflation---I wanted to add this info to a presentation I plan to give this Wednesday.
My impression is that there at least has to be enough gas released inside the pitcher to maintain the inside pressure near equilibrium with the pressure outside, or else it would seem that the pitcher wouldn't be able expand outwards as the pitcher cells grow/multiply. So would this gas be CO2 or oxygen? Also, is this gas developing from increased respiration from the inner cells of the pitcher, the entire pitcher, or none of the above? It's not that big of a deal, but I was just curious.
Thanks in advance for your input.
Aaron
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Post by bombsboy on Feb 22, 2011 3:07:39 GMT
I know that once the pitchers touch the ground, they tend to stop tendril growth and begin ballooning. If the cap is pre-maturely opened, the same thing occurs. the ballooning's gas would most likely be oxygen, as that is what plants release. I beleive the gas production is at it's normal rate.
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Post by John Brittnacher on Feb 24, 2011 2:35:51 GMT
I doubt very much it inflates. What is wrong with just growing?
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sundewman
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Happy Growing!
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Post by sundewman on Feb 24, 2011 4:30:10 GMT
Hey John, My original thinking, based on this video (http://www.youtube.com/watch?v=trWzDlRvv1M) is that if the pitcher was closed, wouldn't there need to be gas emanation from the pitcher in order to keep the sides from imploding as the pitcher grew larger...
Perhaps I'm incorrectly assuming that there wouldn't be free gas flow from the pitcher epidermal cells into the inner section of the "inflating" pitcher...
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Post by frenchy87128 on Feb 24, 2011 15:08:22 GMT
Hey Aaron,
I don't think gas emissions is what gives the pitcher it's hollow structure. While I would agree with you that surely the cells emit some Oxygen, I seriously doubt that this gas would be able to keep the pitcher inflated. For one the lid does not seem to be a gas tight lid and secondly you can actually slowly squeeze an inflating pitcher to the point where one side of the pitcher will meet the other. This does not hinder the pitcher from inflating.
My thoughts is that cells on the inside and outside of the pitcher walls grow at the same rate increasing pitcher height. However, I would also think that the cells at the bottom of the pitcher (near the tendril) are the cells responsible for giving the pitcher it's hollow, rounded structure as they tend to grow somewhat horizontally. I have seen numerous pitchers inflate with the 'little lid syndrome' or all around missing an entire lid. The pitcher itself does inflate properly even with this missing lid.
Take care,
Yann
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Post by ICPS-bob on Feb 24, 2011 18:16:07 GMT
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sundewman
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Happy Growing!
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Post by sundewman on Feb 25, 2011 2:16:32 GMT
Thanks, you guys- that was exactly the info I was looking for. Don't know how I missed the pitcher structure/ development article. Not growing these plants, myself, I wasn't able to try any experiments as Yann described, and just wanted to check Yeah, they definitely overdo the dramatic effects in Attenborough's videos - especially with Venus Flytraps snapping shut with a creaking sound and a slam, lol.
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Post by Dave Evans on Feb 26, 2011 1:31:27 GMT
Well the buds stay flat, empty of air until it is mostly grown. The pitcher does continue to grow and expand after opening, so really they are sucking in air as they open.
I would simply indicate the pitchers inflate because of their growth, not due to gas pressure. There isn't anything rubbery or stretchable about the growing pitcher. There isn't any gas pressure, if there was the delicate baby pitcher would rupture and probably die.
The actual growth of individual cells appears to mostly involve control by auxins; which is how they ensure the pitchers are placed correctly--standing up straight so the trap works. As the pitchers grow, they mimic the appearance of an inflating balloon; especially because any colored patterns stretch out as different parts grow at different rates. The main difference being the air is being pushed into the balloon forcing it open and into a new shape. As the Nepenthes pitcher grows, it displaces air which forces its way into the pitcher to equalize the pressure. The air is actually pushing on the pitcher from the outside opposite how the balloon inflates.
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Post by meadowview on Feb 26, 2011 17:01:02 GMT
Hi Folks:
This is an interesting topic. Dave, isn't the developing pitcher supposed to be hermetically sealed? If so, as the developing pitcher increases in volume what gas is then inside the pitcher? I'm not sure anyone has really pondered this question. I agree that any major inside pressure would rupture the delicate leaf but I can see that it might be possible to have a slight pressure inside the pitcher greater than ambient pressure outside and that would keep the pitcher inflated. Someone who wants to lose a few pitchers could stick an inflating pitcher and measure pressure. Looks like a good project for a student.
Best,
Phil
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Post by ICPS-bob on Feb 27, 2011 0:29:55 GMT
Someone who wants to lose a few pitchers could stick an inflating pitcher and measure pressure. Looks like a good project for a student. In addition to measuring pressure, someone with access to a gas analyzer could determine the composition of the "air" inside the unopened pitcher. I agree that this would be a great project, the results of which I would happily print in CPN.
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Post by kitkor on Feb 27, 2011 2:03:43 GMT
Interesting idea. It's not clear to me how someone would accurately measure pressure in the pitcher. It's not entirely rigid, so the act of sticking a measuring device into the pitcher might artificially produce a higher pressure, like what happens when I squeeze a pitcher before it has opened.
I think we have the necessary equipment to analyze the gas mixture and this would be an excellent undergraduate student project.
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Post by rocktroll on Feb 27, 2011 19:21:04 GMT
Thank you all for the wonderful discussion I too thought that analyzing the internal gases would be intresting. The only exprience I have with gas testing is the DRAGER unit from Germany. This was used for explosives/co2 before entering an enclosed space. I'm sure a more accurate way is possible to quantify and am sorry for the ignorance.
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PHaze
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Post by PHaze on Mar 3, 2011 17:00:39 GMT
Some of these questions could be answered with a simple experiment not requiring any sophisticated equipment. Submerge some developing pitchers in water before they start inflating. As the submerged pitchers inflate, do they fill with gas or liquid?
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Post by Dave Evans on Mar 4, 2011 1:04:20 GMT
Dave, isn't the developing pitcher supposed to be hermetically sealed? I rather doubt it. The peristome and lid appear to be separated by a layer of hair, which ends up under the peristome when the pitcher is done growing. Prior to the layer of hair forming, perhaps it is sealed, but I think the pitcher is pretty far down the line as far as differenciating tissues by the time it starts to "inflate". I.e. there isn't any reason to suspect it is "sealed"...
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Myles
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Post by Myles on Mar 4, 2011 5:43:50 GMT
From my limited botany experience, once the general shape of the pitcher is formed, most cell division would stop and cell elongation begins. Obviously there is still some division but when cells first form they are small and compact then later over time stretch. This is more obvious with leaves and stems. Internode lengths start short nearest to the apical meristem and show delayed enlargement stetching the internode length greatly. This being similar to how leaves start small and thicker and as they get to there mature size often times become thinner.
I am no Botanist but I am talking based on my education. As for the gas, I'd assume as the plant grows the pitcher and the tissues starts to take form, air can slowly pass through the plant's tissues. After all, gas exchange is needed and designed to happen efficiently through the stomata and into both the pallisade and spongey mesophyll layers. I'd be surprised if gas exchange wasn't possible through the pitcher walls especially with how slow the increase of gas in pitchers is.
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