Mosses and Liverworts

A close up of moss.

NPS / R.Wang

What is that green, fuzzy, carpet-like stuff growing on the forest floor? It’s most likely moss! Moss and liverworts and hornworts are considered some of the oldest plants on earth. They are types of non-vascular plants, classified as bryophytes that grow in the woods of Katahdin Woods and Waters National Monument. Bryophytes have no transporting stems or roots. They use tissues called rhizoids, instead of roots, to attach themselves to surfaces on which to grow. This allows bryophytes to exist without soil. Moss and liverworts absorb needed nutrients directly through surface tissues, which is why they typically live in moist environments.The forest can feel serene and quite fairytale-like when the sunlight trickles in through the thick canopy and spotlights the moss blanketing the forest floor. When you take a hike at the monument, make sure to take a moment to stop and notice the tiny plants growing on the surface of trails, trees, and even rocks.

 

Haircap moss growing on a trail.

NPS / R.Wang

Moss: Small, But Mighty

Mosses are diverse and found worldwide. They reproduce through spores rather than seeds and do not have flowers. They are multicellular and have green chlorophyll, which is a key factor to the photosynthesis process (the way plants turn light into usable energy). They also obtain their nutrients by absorbing water and nutrients around them, meaning they are bryophytes (non-vascular land plants). Mosses also have a midrib structure, a line that runs down the length of the leaf. Although small, mosses are mighty. These plants are resilient and grow on unlikely places such as tree trunks, cliffsides, and even on top of boulders and rocks. They also have the ability to go dormant in the absence of water, but once they rehydrate, they are able to grow again. They grow where most other plants cannot. There are even aquatic mosses, which can live underwater in freshwater environments. On a snowy winter day, you will even see these green plants thriving. They have adapted ways to take advantage of the sunlight during the winter. Mosses are also currently being researched for their antimicrobial properties. Mosses play an important role by providing habitat for insects and other invertebrates. Mosses also contribute to stabilizing and reducing soil erosion in areas where they grow. As resilient as they are, moss are also sensitive, which make them good indicators of pollution and contaminants of the areas they grow. Moss play an important role in the global carbon cycle by capturing and storing atmospheric carbon dioxide, a process called carbon sequestration.

 

Liverworts

Although closely related, liverworts are different from mosses, which are also bryophytes. There are two types of liverworts: leafy and thallose. The leafy liverworts are most frequently confused with moss; however, they differ from mosses because they have cilia. Thallose liverworts, on the other hand, do not have leaves and instead look flattened. Liverworts also never have stomata or ribs running down the length of their leaves.