Carnivorous Plants Website
Carnivorous Plants in the Wilderness
by Makoto Honda

Venus Flytrap Trap-Lobe Curling Sequence 2 2018-June-06  HOME

2018-June-06   Time: 16 hour : 00 min : 00 sec   ____   Frame 00

This is a test of Venus flytrap leaf-closure behavior.
"Narrowing Phase"

This experiment attempts to get some insight as to the possible shift of turgor-pressure-difference location.
It appears the pressure differential first appears in the upper half of the trap lobe (closer to the lobe margin),
right after the second action potential is generated.
That results in a swift "snap" motion of the trap (buckling).
If no more touch, no further leaf movement is observed,
and the trap will re-open in 24 hours.
However, if the trigger hairs receive further stimulation, the trap enters into the narrowing phase.
In this phase, it appears the location where the pressure differential between the upper and lower lobe surface builds
is slowly shifting downwards toward the midrib.
This results in constricting behavior of the trap, with the trap cavity getting smaller and smaller.
The shift of pressure location is something Lloyd describes in the tentacle behavior of Drosera.
In the case of tentacles, the turgor-pressure difference appears near the tentacle base,
and gradually moves upward towards the tip of the tentacle.
In the case of VF, it appears the pressure is coming down towards the midrib...

To do this experiment, I had to cut a trap leaf in three places:
1)  Cut off the trap end (not quite half, just 1/3 from the end)
2)  Remove one of the two lobes so the remaining lobe can curl freely.
Must avoid the midrib.
3)  Cut the remaining lobe half way vertically close to the midrib, as below.
Without this cut, the center portion of the lobe cannot curl freely still.