For this lab I knew immediately that I wanted to use the foldscope to look at something related to leaves. Princeton has stunning fall foliage, and every October and November I make it a habit of noticing and taking pictures of the beautiful leaves around campus.

Of course, it’s now January and most of the leaves have fallen, and the beautiful fall colors have faded away to varying shades of brown and gray. However, it’s been unseasonably warm this winter and therefore some stubborn (albeit dried out) leaves are still clinging to their branches, and since we haven’t had a real snow yet there are many more decaying leaves scattered around Princeton’s many lawns.

For my small investigation, I decided to look at leaves from various tree species at varying stages of decay. My main interest in pursuing this project was to see how the micro-structure of leaves would change with degradation; would there be a visible difference in the foldscope between more and less degraded leaves? Do some parts of the leaf (stem matter and primary veins vs. blade) decay faster than others?

To conduct this mini experiment, I collected six leaf samples of varying states of degradation: little to no degradation (I picked these off of tree branches), medium degradation (some discoloration/decay), and high degradation (high discoloration/decay).

I then looked at each leaf sample with the foldscope. It appeared to me that as degradation increased, the amount of pigmentation remaining in the leaves decreased; while all the leaves appeared brown or brownish-grey to the eye, under the foldscope the low and medium degraded leaves had a reddish color, while the highly degraded leaves had brown/grey coloration.

Additionally, the moderately and highly degraded leaves both had black clumps forming on the surface of the leaf – this could be dirt or some sort of fungal/mold growth. Finally, the cells of the leaves in the moderately and highly degraded leaves are less densely packed than in the lightly degraded leaves; in the moderately and highly degraded leaf images, you can see light spots where parts of the blade have decayed in patches. The blade seems to decay before the veins or the stems; no evidence of decay is visible on the veins or stems in the images.

I conducted this investigation as a part of Rob Pringle’s EEB 321 class.