You might not notice this minuscule plant, but it has an important job to do

Much of the time we barely notice mosses. Even during the less colorful months of winter, they’re just scattered patches of green on rocks and tree trunks, moist soil, and the edges of walkways.

Worldwide there are over 10,000 different kinds of moss (estimates vary), and they’re found in diverse environments, from polar regions and prairies to boreal forests, deciduous woodlands, freshwater wetlands and the tropics.

Look closely at a patch of moss, and you’ll see dozens, perhaps hundreds, of tiny green plants packed closely together. They’ve got slender, delicate stems, root-like threads called rhizoids, and simple leaves that are mostly a single cell layer thick.

These minuscule plants contain chlorophyll and can manufacture their own food. Arising originally from spores, they represent one phase, or generation, of a complex life-cycle.

Some of the moss plants in a clump are male; others are female. Mosses need moisture — even just a thin water film — in order for sperm to swim to the egg cells housed within microscopic structures on the female plants.

Fertilized eggs eventually give rise to the next generation in the life-cycle: leafless, brown stalks topped with capsules full of spores. These unassuming little plants stay attached to the previous generation and, in fact, depend on it for food and water.

Moss clumps, then, may contain two types of plants at the same time.

Eventually, the spore capsules dry out and release their contents. Spores that land on moist sites will germinate and grow into more sexually reproducing moss plants, thus continuing the life-cycle.

Mosses are usually only a few inches tall, since they lack the specialized conducting and supportive tissues distinguishing the “vascular” plants (oak trees, azaleas, etc.) that most people are familiar with.

They also lack flowers, seeds and fruits. Most species are familiar only to experts.

But mosses have important ecological roles and human uses. Some are among the first plants to colonize rock crevices and other new habitats. Mosses reduce soil erosion on disturbed ground, and some species are important bio-indicators of air pollution.

Peat moss (Sphagnum) is a major component of bogs. It’s also valued as a soil additive by gardeners, since it can absorb up to 20 times its dry weight in moisture. This amazing water-retention capacity also accounts for its previous uses for wound dressings and diapers.

Incidentally, the iconic Spanish “moss” of the Lowcountry isn’t a moss at all. It’s actually a flowering plant in the same family as pineapples.