the rainwater can easily run away. I think because the fluid is so
slimy
and the lower part quite narrow, one could treat the fluid in the
lower
half as some kind of column. The rain has little chance of disrupting
or
mixing this column which is supported by both, the narrow shape and
the consistence. Insects (very small ones at least in the greenhouse,
which are cought very efficiently) sink down and can not be washed
out. As the rain runs off quickly there is not much danger of the
pitcher fluid being diluted and nutrients being washed away.
Nepenthes inermis
0 = unprotected liquid
x = slimy liquid-column
\000000000000/
\000000000/
\ 00000/
\000/
IxxI
IxxI
IxxI
2.) N. lowii:
The pitchers consist of two parts. The lower one is bowl shaped while
the upper one is plate like and I would think that it contributes to
insect-attraction if you think of the red coloration. The channel
between both parts is quite narrow, so that a mixing of the fluids
which are in the lower part, where also the digestion takes place
seems
to be very unlikely when a normal rain goes down. I think the bowl
shaped lower part is an alternative construction to the column of N.
inermis and dubia but results are the same.
In both cases a mixing and washout of the nutrient-rich soup of the
lower part is prevented and the upper part can freely be disigned by
evolution for a maximum of trapping efficiency. The construction for
me seems to be quite similar to Heliamphora, by the way. However as
the pitchers are too static another way of water run-off was chosen.
Another (but quite similar) design was chosen in case of N.
ephippiata:
Here the "bowl" is bent upwards again along the tendril (sorry for
limited ability to express myself in English language) so that a
region
is created which is quite isolated.
N. lowii
x = protected liquid
o = unprotected liquid
_________________
\ 000000000000000/
\ 00000000 /
II ___\ 00000 /__
II _/ 0x0x0x0x0x0 \_
II _/ xxxxxxxxxxxxxxxxx\
II /xxxxxxxxxxxxxxxxxxxxx\
II IxxxxxxxxxxxxxxxxxxxxxI
\\ \xxxxxxxxxxxxxxxxxxxx/
\\_\xxxxxxxxxxxxxxxxx/
N. ephippiata
x = protected liquid
o = unprotected liquid
I I
I I
I I
I \ _________
I x \ \ ooooooo /
I xx \___I ooooo /
\ xxx0x0x0x000 /
\xxxxx0x0x0x0/
3.)N. ampullaria:
At most places where I saw them they were growing under trees in
deep shade. In this environment there is not much danger of a hard
rain since most of the water is trapped by the trees and a lot of
water
uns down at the stems of trees.
Lid hairs:
I have no real idea however do you have any idea of the nature of the
huge slime deposits which are produced by N. lowii and N. ephippiata
between the hairs? I tasted this slime and it was not sweet (maybe a
very dull sweetish taste?!) but I must admit that I never checked
what
the slime really consists of. If however the slime consists of
something
(sugars or proteins) useful for insects like ants the hair might
function
as a ladder to ease the way to the food.
Another possible function which seems to be more likely to me could
be to support the slime which might work as an attractant for insects
and to fix the deposits so that they are not washed away by rains. If
one considers that the slime deposits reach sizes of more than one
cubic-centimeter a need for a support seems to be very likely to me.
I know that all my ideas are pure speculations but I hope this is OK
in
that forum.
All the best
Andreas
Andreas Wistuba
A.Wistuba@Dkfz-Heidelberg.de
Phone: +49-621-705471 Fax: +49-621-711307