Got Nature? Blog

Climacium. Click on photo for larger view. Photo by Sally Weeks, Dendrology Specialist, Forestry and Natural Resources, Purdue University.

Do you ever wander through the cold, winter woods, seeing only shades of brown, but then happen upon a lush, dense carpet of green moss that leaves you with a sense of awe? You wonder how a plant can be so green when the weather is so cold?! You wonder how such a miniature plant can be so hardy?!

Mosses are classified as Bryophytes and represent a group of the most ancient plants on earth. They predate the dinosaurs by several hundred million years! Although they are greatly outnumbered by today’s advanced plants, they have several amazing tricks that enable them to compete.

The most impressive is physiological drought tolerance, known as poikilohydry. Mosses have few structural characteristics that would allow them to maintain correct water balance, unlike advanced plants. When conditions are dry, mosses simply dry up and become dormant until rehydrated. Another trick that gives them an advantage over winter-dormant plants is that during this cold season, as long as the temperatures are above freezing and the moss is hydrated, it will photosynthesize.

Climacium. Click on photo for larger view. Photo by Sally Weeks, Dendrology Specialist, Forestry and Natural Resources, Purdue University.

Mosses readily reproduce vegetatively and can spread and carpet an area in short order – another survival trick. Although mosses are not dependent on spores for reproduction, these propagules are transported by weather systems, and many species are found transcontinentally.

While I greatly admire any plant hardy enough to remain green all winter long, and I love mosses in general, my favorite species has to be the robust tree moss (Climacium dendroides). Its specific Latin name (dendroides) literally translates to the English “like a tree” and refers to its large size (for a moss) of 3-4 inches in height. No other moss is close to this height. A large carpet of Climacium tempts one to use it as a natural mattress for an overnight stay!

It is said that to know mosses is to feel a nearness to the texture of nature. You don’t really need to know any particular moss species, but next time you encounter a lush green patch, take a close look at the detail and texture of the plants. It is just one more layer of nature in all its architectural beauty.

For more resources, view Shrubs of Indiana and Shrubs and Woody Vines of Indiana and the Midwest.

Sally Weeks, Dendrology Specialist, Retired
Forestry and Natural Resources, Purdue University