Mosses are a fascinating division of plants distinct from more commonly recognized groups such as trees, grasses, and ferns. Mosses are also known as Bryophyta and are one among three groups of bryophytes, which are non-vascular plants with wholly enclosed reproductive systems. There are more than 14,000 species of Bryophyta that grow in an array of colors and can be found on all seven continents. While most species prefer damp and shaded environments - often woodlands - some mosses thrive in desert areas, as well as ice-covered regions such as Antarctica.
Mosses are typically 0.1–3.9 inches (0.2–10 cm) in height, though select species can grow up to 20 inches (50 cm) tall. Bryophyta lack the root structure characteristic of many plants, instead attaching themselves to their environment via hairy protrusions called rhizoids. Most Bryophyta collect water and compounds through the air, using them in conjunction with the sun to create food by way of photosynthesis. Mosses don’t have flowers or seeds, but reproduce via spores.
Contrary to popular myth, mosses don’t just grow on the north side of trees, though many Bryophyta do avoid southern exposure due to the sun’s intense rays. Fallacious lore aside, there are actually some truly bizarre and amazing moss facts that surround these little, unassuming green clumps. So, with most of the basics out of the way, read on to take a deeper dive into some of the crazy things Bryophyta can do.
The First Land Plants Were Moss-Like
Bryophytes are the closest living relatives to the very first plants to make land on the planet, approximately 500 million years ago. Descended from freshwater green algae, these moss-like organisms had an outer biopolymer that protected them from temperature changes and constant UV radiation, allowing them to withstand the unique stresses of terrestrial life.
Mosses Might Have Triggered An Ice Age
You wouldn’t think that a small-leafed, rootless plant could wreak much havoc, but according to scientists at the University of Exeter in the UK, that’s exactly what bryophytes did when they first came on the scene almost half a billion years ago. Professor Tim Lenton proposes that when these plants started to cover the land, they altered the bedrock’s composition, causing the earth to ‘suck’ carbon dioxide from the air.
Insufficiency of the greenhouse gas cooled the planet and led to the Ordovician-Silurian Extinction Event - the second largest in earth's history.
Moss Leaves Are Only One Cell Thick
Moss leaves will vary in size by species. Leaf size can also be different along a leaflet of the same plant. However, many mosses have leaves that are just one cell thick, measuring an incredibly slight one-hundredth of a millimeter.
Mosses Can Extract Water From The Air
While most plants sequester water from the ground, many Bryophyta absorb the water they need as it passes through their leaves. Perhaps the most impressive example of this phenomenon is exhibited in desert moss (Syntrichia caninervis), which uses barbed ‘awns’ at the end of its leaves to capture moisture.
The awns allow the moss to take in water from the occasional rain, but also from mists and even fog.