As I walked around Princeton looking for inspiration, I found myself in a large grassy field. The area was lined with oak trees, and I knelt down beneath their branches in a comfortable spot. Laying my hand on the ground, my fingers dug into the exposed dirt beneath the tree.

Aha! Dirt! I though. Something to study. Digging around, I saw patches of sandier beige soil and other areas of dark brown soil. I started to wonder if this soil was similar to most soils on campus, or had less clay than areas near the river. This spurred more ecological questions, about how soil types would affect what types of organisms that could survive in the area, the amount of water that was retained in the soil, and how the constant mowing of the field affected the species that could survive in the area.

I proceeded to put the dirt under the foldscope and took a look.

After looking at the dirt, I couldn’t identify much. I did see more grains of sand, and dark clumps of organic matter. Also, I saw a root that I had accidentally torn while scooping the dirt. After seeing this I decided that it is more interesting to look at what is within the dirt than the dirt itself. First I started taking samples of grasses from the middle of the field. They were difficult to pull out, for their roots were knotted together. This evoked more questions: How does the density of grass effect the root growth? How deep is the average grass root? How does this change when there are sprinkler systems? Are there any competative interactions between grass species and the oak tree?

I proceeded to pluck different plants from the ground and observe their root systems. I took some species of grass from high density areas, and some from low. I removed another completely different species (which I could not identify) and saw that the root was less branched than the grass and went deeper.

Since these two specimens, (as seen above), had such a different looking root systems, I decided that these were going to be the focus of my next foldscope investigation. I selected one piece of root from the unknown specimen and one from the grass.

First I looked at the long, thing white root (from the unknown plant). The main section of the root was too large to clearly focus on, but I was able to see the smaller branching of the root. The root appeared to have long tube like shadows passing down their centers (as seen in the first and last image). Perhaps these are for transporting water to the leaf of the plant. Another interesting observation is that the end of the root is rounded in this plant (last image), while in the grass root system there is a flat edge to the root head (last image of second series).

Although it is difficult to see from this picture, these roots of the grass much more branched and intertwined, while the specimen above’s roots all derived from a thicker main root. Also, the roots of the grass were a much darker color and appeared to have a rougher surface. In a future investigation, it would be interesting to see why the roots are brown and whether this trait is special to this sample or most grass roots. Are brown roots an indicator of health?

Overall, these foldscopes were incredible! It was amazing to see the complexity of the root system right in the field. However, to understand what I saw, I will have to spend much more time observing and researching root systems…

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