Picture from Princeton University

Princeton Prospect Garden is normally a lush and vibrant assembly of plant life in the heart of Princeton University’s campus. Unfortunately, due to the rush of college life, most students pass through quickly, overlooking the unique diversity of plants, flowers, and natural ornamentation that speak to the beauty of nature and the campus as a whole. Sadly, during winter, the lush garden loses its luster, fading away to a carpet of ivy surrounding the withered remains of plants dreaming of spring. Of course, the University takes great pride in this space as exhibited through its frequent and careful landscaping.

This year, though, the El Ni ñ o weather has provided campus an unseasonably warm winter, sparing Prospect Garden from being buried in the snow. Normally concealed in a blanket of white, the plants now stand in their full glory, even in the middle of winter, although still succumbing to the lackluster browns and greys that dominate this time of year. Yet, the plants were still clearly visible and the withering away revealed some of the smaller, underlying plants that call Prospect Garden home. Indeed, without winter affecting the larger competitors, the smaller plants would likely stay hidden behind and below a curtain of color. Intrigued by the hidden flora, we looked more closely at three of these hidden plants, which dominated the undergrowth amidst the ivy and pines.

Besides the ivy, this plant was easily the most abundant on the ground. It lay strewn about amongst the ivy in these characteristic clumps. Pulling the leaves apart, there are nodules visible along the stems.

On a closer scale, each leaf had few large veins, quickly branching off into fine vascular bundles. In between the brown veins, you can see the cell walls of the leaf epidermis, seemingly hollowed out, perhaps to reduce what is lost as the leaf decomposes over dinner. We found a second bundle that shows the next step of winter’s touch on this species of plant.

This skeletonized version of the same plant was a fantastic find, showing the large veins with branched vascular bundles, forming the transport network critical to the survival of each leaf and plant. The decomposition is marked by a bleaching of the tissues and the loss of the leaf tissue not dedicated to transport.

Here, no tissue cells are visible, indicating that the empty cells decay first as the structured transport network takes more time to degrade. Moreover, these veins have sharp edges to them, unlike the still intact leaf of before.

One plant did even better than this species, keeping its leaves intact and showing little sign of decomposition. In fact, the only difference between summer and winter seemed to be the color of the fern.

Interestingly, the plant that best weathered winter had connected leaves, instead of each single leaf braving the elements individually. Indeed, there was a sizeable clump of ferns still standing tall amongst the ivy, whereas the previous plant grew in scattered clumps partially hidden below the ivy.

Here, the veins are completely smooth and uneroded. The tissue cells are abundant and well-defined, still hosting thick cell walls.

Most intriguing, though, was the fact that we were able to discover something quite odd indeed – seeds in winter.

Despite being early January, this tenacious dandelion not only was still growing, but still had a whole head of seeds produced. Since it has such a unique structure, especially when compared to the other decaying plants, we decided to put the seeds under the lens to see the structure that allows this plant to reproduce, much to the chagrin of those who strive after the perfect lawn.

The incredibly fine hairs that feel so soft to the touch actually appear quite abrasive under the microscope. Indeed, they almost look like insect legs bundled together to catch the breeze that will carry the seed to new fields. Indeed, it is interesting in the first photo to see how haphazardly strewn the fibers are at the end of their length, calling to mind the structure of velcro, possibly as an adaptation to catch the hair of a passing animal instead of waiting for the right wind to disperse its seed.

These are simply three small plants on Princeton University’s campus, revealing the incredible diversity showcased on the relatively small campus. Even the simplest of plants, seemingly not even strong enough to break through the canopy of ivy, bear these incredible structures that allow plants to survive through winter, showcasing the incredible diversity that exists even in the smallest of leaves hiding underneath a blade of ivy.

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