Those Overlooked Around Us

As we begin to sense the seasons changing, so do the plants around us. The cold begins to sweep across the landscape, and the trees begin to drop their leaves as they start to hunker down for winter. These leaves drop down to the forest floor, covering my plot with colorful splashes. The grass has begun to gray, many of the flowers are gone, with their stalks having lost their vibrancy as the cold presses down on them. However, not all feel the pressure of the cold. As autumn continues on, and as winter’s snow begins to cover the ground, moss can be found shining in all of its green glory.

This begs the question, why would moss, such an ancient and seemingly insignificant little organism, be able to survive in the snow while the tallest trees have to sleep to make it through the winter? The answer lays in evolution. The first plants on Earth were simple, nonvascular plants, that don’t contain the many complex systems of newer species. From nonvascular plants evolved those with vascular systems, which allow these species to grow in habitats all over the world. Trees and flowers are vascular plants, who have evolved complex systems that allow them to adapt to many habitats but come with substantial trade-offs. Moss, however, is not privy to these complex systems as the nonvascular forefather of many of these vascular plants.

Vascular plants have evolved beautiful systems, such as the xylem, phloem, stomata, and the cuticle, that allow them many advantages over their nonvascular counterparts. The xylem and phloem found in vascular plants can be best thought of as pipes. The xylem pipe allows for water to be channeled from the longest roots to the tallest tree tops. The phloem pipe is similar, acting as a pipeline throughout which the plant can transfer sugar and nutrients. These pipes are important, as they are what allowed for plants to grow tall. Vascular plants are protected from drought, through stomata that allow for carbon to be collected from the atmosphere when conditions are good and the cuticle, a waxy coating that prevents water loss. Many flowering plants have also developed intricate relationships with animals, acting as both their pollinators and seed dispersers.

Although vascular plant systems come with wonderful advantages, they also have heavy trade-offs. Freezing temperatures and air bubbles can clog their pipes, making it hard for the plant to properly distribute water and nutrients. In the winter, freezing temperatures can halt the water within a plant’s systems, a risk so large that many plants cannot afford to take it. So, many shed their leaves and hunker-down for the winter. Thus, as autumn passes through the beautiful flowers that were once the highlight of my plot have begun to disappear and the canopy that once stood high above me can now be found at my feet. Yet, something green can still be found- moss.

Moss is a nonvascular plant, so it lacks the structures that cause others to hole-up for the winter. Moss thus doesn’t “feel” the cold the way other plants do. Although it seems that having vascular systems would always provide an advantage to plants, nonvascular plants like moss actually have traits that allow them to live in some of the most extreme environments. These features are what allow me to see moss scattered across my plot in New York even as the weather starts to get cold, and what allow scientists to find it in the toughest conditions. Although we are always impressed by cacti, vascular plants that can live in the hottest, driest conditions, we rarely give moss the recognition it deserves. Moss can be found in the coldest place on Earth- Antarctica.

Moss has many traits that make it easy for it to overwinter in cold places on the planet, whether it be through its small size, ability to regenerate, or how it reproduces. Unlike trees and flowers which produce seeds, moss produces spores that are carried by the wind. These spores may not seem important, but they are vital when living in cold and barren environments. Imagine living in Antarctica, a cold and isolating landscape. You are lonely and wish to find a date. Where do you even start? The closest human may not even be on the same continent. And even if you did manage to find a partner, if you were capable of having a child together it would be extremely difficult to raise it in Antarctica. This is the problem that vascular plants have, on top of the features like phloem and xylem that would get clogged by the freezing temperatures. However, imagine that you are able to reproduce asexually, and do so quite happily. This is the advantage that spores provide, as it allows moss to reproduce without the need for a partner.

One may think that small size wouldn’t be helpful to moss, but it actually helps it make it through tough winter conditions. The small size of moss means that it doesn’t require as much sunlight as big vascular plants. This is important in winter, as plants have less access to sunlight over the winter due to decreased amount of daylight. Further, Antarctic winds can be brutal, reaching speeds of up to 200 mph. These speeds would be capable of easily knocking over a tree, but what about moss? Interestingly, its small size gives it a big advantage. Moss is stuck to the ground, and its low center of gravity helps it stay there. This can even be seen in New York, where the forests are filled with trees that have fallen down in big crashes. Yet moss, as tiny as it is, remains perfectly unharmed even after a tough bout of wind. Therefore, the small size of many nonvascular plants can provide a huge advantage in environments with high winds.

One of the most interesting features of moss is its ability to regenerate, a trait that can allow it to live an unbelievably long amount of time. Moss is able to “hibernate” when conditions are poor, and regenerate when conditions improve. It is almost like a zombie, coming “back to life” when the conditions are right. Moss has even been recovered by scientists after hibernating for over 300 years, a feature that allows moss to keep alive even during the toughest of times.

Although we commonly overlook nonvascular plants, they are extremely fascinating and valuable to both the natural world and to humanity. Before nonvascular plants existed, the world was inhospitable to most plants species, animals, and humanity. Nonvascular plants played a large role in converting the planet into the one we currently know, as they were the first to fill the atmosphere with oxygen that made the planet hospitable. Even now, mosses and other nonvascular plants play a large role in helping reduce the amount of carbon in the atmosphere.

Further, mosses have been suggested to impact the formation of the world around us. These plants have been suggested to influence the composition of vascular plant communities, a role that could be extremely invaluable. Nonvascular plants even provide crucial soil and water services, as they slowly break down rocks into soil and filter water. Providing crucial benefits to plant communities and humans, they also are important environmental indicators. Plants such as moss quickly uptake water and air, a trait that can allow us to see how the environment is changing. We can also figure out a lot about evolution from these plants, as the ancestors of vascular plants.

Nonvascular plants have long been ignored, whether it be due to the small size of these plants or because they are less complex than vascular plants. However, being ignored does not mean that these plants aren’t vastly important. Mosses live in the most extreme environments, and play an undeniably indispensable role in nature. We should learn to admire even the smallest parts of nature, as even they can have a huge effect on the world we see around us.