Mosses are all around us, all of the time, and I was interested in investigating whether the Foldscope would be able to generate a good image of some local flora I found on a rock outside the mathematics building (Fine Hall) here at Princeton. In particular, I wanted to figure out whether we could get key identification criteria for moss species using the Foldscope, and see where there are limitations that prevent Foldscope from being a perfect moss-hunting tool. I was able to successfully get leaf-shape and presence-of-midrib, which are two important descriptions of mosses! The issues I expected—and encountered—were focusing-depth and understage lighting.

Mosses are notoriously hard to identify to species, but I was able to determine that it was pleurocarpous, meaning it has a fern-like look to its growth pattern. Using photos from Foldscope, I was able to determine that the leaves were sickle-shaped (because they constrict to a point that bends over) and lacked a midrib (because there is no straight line down the center of the leaf), and these features are very useful for identifying mosses! Sadly, I left my moss-identification book at home, so I can't get any more specific than that. But, to answer my guiding question, it was relatively easy to find the the key identification criteria for the moss using the Foldscope!

I had difficulty getting the scope to focus on the top (the nearest point) of the moss, because it was too close to the lens, which I a problem I have encountered many times while studying butterfly and moth specimens using regular microscopes in Kenya. And because moss is not translucent through its branches, seeing the top of the moss through the stage was also problematic. This is another problem that I have experienced with moths, as well, and but I used special microscopes designed to fix this, by putting a light facing away from, instead of towards, the viewer.

In some of the images, you can see plant cells, stacked like bricks in the mosses. It is truly incredible to see the building blocks of life with a 50¢ folding-microscope! What an exciting view of the cosmos—and the microcosmos!



Part of Professor Rob Pringle's EEB321 class at Princeton University