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'Water Level' mark on the inside of pitchers

I've wondered for some time why nepenthes produce a kind of "water level" mark on the inside of the pitchers.
The result is often the color of the pitcher is quite different below the "water level" mark.
The only explanation I've come up with is that the mark is made by the pitcher fluid being exposed to light when the pitcher first opens and because the fluid itself is often quite sticky it literally freezes/sets onto the pitcher as a fine layer. The thing I can't explain is how the "water level" mark gets so high up a pitcher, when often the fluid is at a much lower level when the pitcher finally opens.

So this leads me to make the assumption that the "water level" mark is then made whilst the pitcher is still inflating and even though the fluid level eventually is much lower, the mark of the fluid at its highest point is still left imprinted onto the pitcher wall.

I also discovered that certain species/hybrids are more susceptible to this happening than others, particularly in pitchers where the interior pitcher wall is lined with speckling.

Can anyone think of a better/ more scientific explanation?

Here's a few photos that hopefully demonstrate the point:

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That marks the end of the waxy zone. Below the waxy zone is the digestive zone. It's not really a water level mark, just the dividing line between the two zones. It is more visible in some more than others. If you ever get access to a good top-lighting microscope, take a look, it'll rock your world. (mean's it's REALLY cool)
 
pretty sure lil hit the nail on the head.
 
At 200 yards! *takes a bow*

It was the result of a few hours of boredom combined with a super expensive work microscope.
 
But the thing I don't understand is how the divide between the waxy zone and the digestive zone ends up looking like the kind of line a tide would make. What determines the shape of the end of the waxy zone? for instance if I tip the pitcher upside down as it is developing, would this make the digestive zone replace the waxy zone entirely? or is it something that is somehow fixed at some point in the pitchers development. It seems to be set once the lid pops open, but I wonder if it is something variable and can be altered during the pitchers development.
 
.... or is it something that is somehow fixed at some point in the pitchers development.

This. It is set in the genetics of the plant. It is the same way our fingerprints are made and our bones are shaped. All about genetics.
 
But the thing I don't understand is how the divide between the waxy zone and the digestive zone ends up looking like the kind of line a tide would make. What determines the shape of the end of the waxy zone? for instance if I tip the pitcher upside down as it is developing, would this make the digestive zone replace the waxy zone entirely? or is it something that is somehow fixed at some point in the pitchers development. It seems to be set once the lid pops open, but I wonder if it is something variable and can be altered during the pitchers development.

I think it'd be a cool experiment to force a pitcher to develop upside-down, but what Lil said makes a ton of sense. Before I read her post, I was thinking it had something to do with it capturing food, but the thought wasn't complete.

It being a "water mark" doesn't really make sens to me because in most cases the water level is between that visible line and the bottom of the pitcher.

Lil's explanation (which is probably 100% spot on) brings up the question, "Why do some Nepenthes not have this 'end of wax zone' mark?" Do some not have a wax zone? If so, why not? :suspect:
 
Some do not have a waxy zone, or the change between it and the digestive zone is just far more subtle. One example: N. ampullaria. It doesn't have this waxy zone, possibly for 2 reasons:
1. Like some people have suggested, it may be on the way to becoming a detritivore, eating falling leaves to gain nitrogen, and therefore not needing a wax zone to hold other prey anymore, or
2. The super large collared peristome is too hard for any insect to climb over once inside, so the plant doesn't need to make the energy consuming wax anymore.
 
It could also be where the pitcher (the pitcher's genetics, if you will) expects the water line to be, and approximates (based on genetic memory) where to put that fill line. Back to the aptly chosen N. amplullaria, amps. have no functional lid, and tend to fill completely. In this case, a waxy zone is useless. Note where N. lowii tends to fill at; any higher and the water will possibly be knocked out wind or be absorbed by the plant.The point is, the plant expects the water to be just... about.... THERE, and there is where it puts that line.

The reason that some lines are easier to see than others is because some plants have a much thicker layer. The wax is somewhat opaque little flakes o fwax, just like the flakes of graphite (as seen by a scanning electron microscope).



I *highly* recommend McPherson's "Pitcher Plants of the Old World". This is all discussed very well in the first volume, as well as a source for my rice stuffed Neps dinner dish.
 
  • #10
It could also be where the pitcher (the pitcher's genetics, if you will) expects the water line to be, and approximates (based on genetic memory) where to put that fill line. Back to the aptly chosen N. amplullaria, amps. have no functional lid, and tend to fill completely. In this case, a waxy zone is useless. Note where N. lowii tends to fill at; any higher and the water will possibly be knocked out wind or be absorbed by the plant.The point is, the plant expects the water to be just... about.... THERE, and there is where it puts that line.

The reason that some lines are easier to see than others is because some plants have a much thicker layer. The wax is somewhat opaque little flakes o fwax, just like the flakes of graphite (as seen by a scanning electron microscope).



I *highly* recommend McPherson's "Pitcher Plants of the Old World". This is all discussed very well in the first volume, as well as a source for my rice stuffed Neps dinner dish.

I'm no Nepenthes expert, but what you're saying makes sense. The plant needs to "know" about how full it will be and "knows" not to make wax any higher than the water line, since submerged wax is useless wax, at least for the plant. You (and that's you as a general audience, not you, you) probably would not bother to use up your precious energy and time making stuff that would be useless to you (even if you aren't a Nepenthes). You might waste some time and energy just making something to kill time or just for fun, but entertainment is something that plants do not need, and these plants never "know" how long they'll live, so time is precious.

And did McPherson seriously put a recipe for rice-stuffed Nepenthes in his book?
 
  • #11
One way to find out. :p




Yes, he did. It's a popular treat in some parts of Indonesia. Yes, I did try it, along with another recipe I found online. FAB-U-lous! I brought some to a BACPS potluck, and everyone there liked them. Those that tried, and didn't chicken out with the banana leaf wrapped rice instead. Even Peter had one.



I would also think that the wax would hinder the effectiveness of the digestive/absorptive glands. It's good to know where to start one zone and stop the other.
 
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