I've got a few questions about the whole process and would love to hear what everyone thinks about it.

First I'd like to establish some common concepts that we all agree on. Note if you have issue with this statements please feel free to quote the offending statement and explain your differences.

-We all agree that bamboo roll there leaves as defensive precursor to leaf desiccation.

-A strong summer sun can cause a bamboo to be unable to keep up with moisture loss, causing the leaves to fold.

-Leaf folding is an adaption of some species of bamboo to survive in colder climates.

-Not all bamboo fold there leaves defensively.

Now for my questions:

What exactly causes a leaf to fold and more importantly how does it return to its prior shape?

Does this mechanism require the plant to expend energy or is it taking advantage of a natural process?

Lastly is leaf folding within the bamboo genus a sign of convergent evolution or divergent evolution?

Here is what I think and I could be wrong so please be gentle. I think leaf folding in general is a partial desiccation event along the "keel" and edges of a leaf. I also think its a plant driven process in response to adverse conditions. I believe a chemical signal is produced in the leaf that tells the "keel" cells to shut themselves off and the message propagates from there to the rest of the leaf. When closed off they do not exchange sap/water but conserve until conditions change. When the environmental conditions have improved a chemical signal is exchanged that tells the leaf cells to open up and transport sap/water. Regarding divergent and convergent evolution I think that leaf folding is sign of divergent evolution. My reasoning is as follows some species do not protect the leaves by folding them, they instead suffer damage till they go blond and fall off. Other species have exaptationed leaf curling to survive in colder winter climates where the other bamboo species cannot follow them. Finally in some bamboo species protective leaf curling will occur even if the plant as ample water, but cannot keep up with transpiration demands of summer afternoon.

_________________
M

The mechanics are Hydrostatic pressure.
marcat