What Autumn “leaves” behind

In Princeton, New Jersey, autumn is in full swing. There are leaves all over campus. I personally love stepping on them to hear the crunch. With fall senescence upon us I thought it would be interesting to get a closer look at the leaves that I see constantly. One part of what makes Autumn people’s favorite season are the beautiful variety colors we see from leaves undergoing senescence. The leaves turn brown, red, yellow, and a mix of all three. 

I chose to look at yellow and red leaves I found on the ground near the building where we have lab. There are rows of these gorgeous red trees and a couple colorful bushes. I picked up a couple of small leaves and put them in my foldscope slides to see what I could find. 

In terms of looking at the “ecology everywhere”, I considered the huge role plants play in powering our whole world. Their most amazing and crucial job is to photosynthesize, but what happens when they lose their chlorophyll and are no longer able to do that? What do their cells look like then? Even after they lose the ability to photosynthesize, they don’t lose all value, they simply move on to the next phase of their contribution to the environment; they fall to the ground, decompose, and add nutrients to the soil, aiding other plants to grow.

As I collected my samples, I wondered what produces these wonderful variations in color that we so appreciate? Why are some leaves red and some are yellow? Is it a factor of the species itself? Or is it about the stage of senescence a plant is in? 

After taking pictures of the leaves I noticed that they all had little water droplets on them and I could see the individual cells. The water droplets were interesting considering that the leaves were dry when I picked them up. The inability to see individual cells may not be significant since it took me a while to get clear pictures of the leaves with my camera. The presence of the water sitting in the surface may be explained by the lack of photosynthesis. Without that process, the dead leaves have no more need nor capacity to take up water so the water simply sits on the surface. This is my theory at least. On the leaves themselves I noticed some spotting in the color. Some areas of the leaf were more saturated than others, I wonder why this is? I suppose this also may connect to my other questions about what exactly produces the color of dead leaves. 

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

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