Once fall comes in New Jersey, the leaves start to come down, albeit slowly. Today is the first day of December, and still, leaves remain dotted at odd intervals throughout the trees. Winter has come on with time. On the lawns and paths of Princeton University, the downed leaves stack up, then float by with the wind. While walking to class this morning, the Princeton facilities crew were out with a John Deere vacuuming up leaves for the winter. Otherwise, the decomposing leaves amass under the snow, blocking the grass from accessing one of its most important resources: sunlight. 
In the time that the leaves have since fallen, they have already begun to exhibit signs of decay. Even during the time that leaves are attached to trees, they maintain the ability to serve as abundant habitats for microscopic organisms. In fact, scientists have discovered that microscopic water films on top of leaves specifically enable bacterial life even when leaves appear dry to the naked eye (Grinberg et al., 2019). 
All this considered, I took out the Foldscope to see what might be found on a recently departed leaf. Here is the leaf from which our sample was taken:

Although the leaf exhibited signs of decay, we could not pick out the specific organisms working away at the leaf. Perhaps this leaf has mostly been consumed by visiting herbivores (insects and the like), or perhaps molds or other fungi too small to pick up are responsible for its decay. I do still wonder what is responsible for all the brown spots like this one that we observed up close:

Although the Foldscope didn’t seem to provide any insight into this curiosity, it did help reveal the individual hairs of a dense “fuzz” on the surface of the leaf:

These outgrowths are known as trichomes and serve as an important defense against herbivory. While trichomes may seem harmless on the human level, they can serve as an often lethal barrier against a visiting insect or small organism. This strategy can be a critical physical defense in the category of resistance, keeping herbivores from even accessing the plant as a food source. Here is an example of the impact of trichomes on a microscopic level from Eisner et al. 2019:


Amazing to see plant defense at work! 

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