I conducted this project as part of Professor Pringle’s EEB321 class at Princeton University.

I'm interested in why, on a single tree, some leaves die sooner than others. Sometimes, some leaves die when others leaves permanently stay alive. Do trees let some leaves die on purpose, or do they "fail" to keep the leaves alive?

To gather more evidence related to these questions, I gathered a dead leaf and an alive leaf from a tree outside of the Frick Chemistry Building in Princeton University.

First I placed the alive leaf under the Foldscope:


And then the dead leaf under the Foldscope:


I noticed that the dead leaf had less density to it, and less structures packed inside the cells (or at least what I think of cells). The cells seemed dried out, which of course aligns with the dead leaf's macroscopic appearance. The alive leaf seemed to have tiny sparkling structures within the cells, which I think could be chloroplasts, although they could also be water droplets.

I was also wondering about how the dying process affects the nutrition content within the leaves. Could an animal that eats the living leaves of a tree also extract a smaller amount of nutrients from the dead leaves? If not, what is the cellular mechanism that causes the leaves to be indigestible? How do animals modulate their diet based on leaves dying in the fall and winter?