Pitchers with Reflexed to Reduced Lids

[rainforest]

The function of the pitcher lids is to keep out rainwater from filling, overflowing pitcher fluids, yet some species have reduced and lids which flex outwards.
N. lowii for allowing animal poop to enter pitchers.
N. ampullaria for allowing debris and fallen fruit to fall in (hence close clustering of open mouths skyward)
N. inermis to allow rain water to fill cup and allow heavy fluid below to be more viscous (hypothesis)
N. Jamban for similar reasons and allowing peristome to become more noticeable
N. fusca (this is a strange one, anyone has any ideas?)
N. veitchii (lids pointing straight up)

Add your species to this list and hopefully with a guess of its reasoning.

Michael

[sockhom]

You have to add N. dubia as well, Michael .
I don't have any interesting hypothesis at the moment.


François.

[jefforever]

How bout Nepenthes eymae uppers? They're not really flexed outwards though.

[rainforest]

But this is what a hypothesis is all about. Cite an example and say what you think nature intended them to do with it.

I also want to say that N. lowii needs water to dilute the pitcher contents for the pitchers to effectively absorb animal scat to work. My lowii's and lowii hybrids all need this rainwater (or tap) to overflow their pitchers (maybe like a toilet bowl) to settle or remove unwanted trash from clogging or blocking.

I have seen my N. fusca make droplets of reddish nectar drip from their thin lids just over the mouth of the pitchers. Dropping in like blood in a clear pool of fluid below. This sight probably attracts every insect in view of this spectacle.

M

[rsivertsen]

Hey guys, I've been having this discussion with several experts for decades! The fact is that these plants are not talking, and the mystery goes on despite our hypotheses, and speculations. However, we can take look back at their evolutionary trail and might find some clues.

In the part of this planet where Nepenthes grow, there are essentially only two seasons, wet and dry. They most likely developed these pitcher adaptations in order to store some water to survive those brutal dry seasons; the ones that also took advantage of absorbing and assimilating the nitrogenous matter of all the critters that just happened to fall and drown into those adaptations had a clear advantage in competition, especially where there is almost no soil, and little available nitrogenous matter for most plants.

You might notice that in older pitchers, and during a dry spell, the upper parts are the first to collapse, lid closing and all, while the lower, digestive parts seem to linger on for up to a full year or so.

Sometimes evolution starts in one directions, but then takes a sudden turn when another advantage has been realized that offers a better competitive advantage.

Food for thought, - Rich

[nepsaroundthehouse]

I do notice that my Nepenthes with the reduced lids in the upper pitchers usually catch only flying insects, while the lowers generally catch ants and other crawling insects.

Joel

[rainforest]

Regarding the less colorful upper pitchers, many flying insects don't see true colors. Many respond of uv simulated color. If someone could do a uv reactive photo on some of these green uppers, perhaps we'd see a different picture. Ground pitchers probably have more color because of insects that inhabit the lower canopy probably rely on color for distinguishing among the competition of available plant materials. Aside from moths and butterflies that do see color, especially red pigments, many flies, mosquitoes, even bees rely on the uv patterns to find nectar etc. Upper pitchers probably tend to be colorless because they would attract birds (who can see colors very well) that may attract, destroy or peck at these pitchers to them it may appear as edible flowers and fruits. This is why N. lowii may be so woody in texture and have a bright red interior (birds see red).

But getting back to lid development, many species find that these reduced/reflexed lids are beneficial for capturing more prey or specific food targets. Obviously water getting into these pitchers must be an advantage or requirement since these plants do occupy rainy regions, and water does get into them. Perhaps it may be a way to get rid of prey that have been in it for too long a period and the pitcher needs a new capture of fresh prey to keep these pitchers functional. I have seen some pitchers with reduced narrow lids dip over when rain has filled them to the top, just enough to get back in position after dispelling its contents. These pitchers have heavy viscous fluids that are not affected by dilution.

It is also interesting to see if many that do have reduced-reflexed lids also have viscous or heavier than usual pitcher fluids. This may be true with N. fusca, inermis, etc.

M