Mosses

A dirt path winds between fallen, moss-covered logs and tall evergreens draped in hanging, green mosses
The many rainforests of Olympic provide ample growing space for moss

NPS Photo

Olympic National Park is well-known for its expansive temperate rainforests. Millions of visitors each year stroll through the greenery of plants to be awestruck by the neck craning views of towering spruce and hemlock trees rising over a hundred feet above. With exciting panoramic views and surprises around each mass of roots, one may overlook some of the truest champions of these moist habitats. Astonishingly this often-overlooked hero can be found all around you from the canopy above to the forest floor down below. Even on a simple, wet and rotting fencepost one may find a mini-forested world all its own.

 
A grey fence post holds tufts of moss sprouting from the top and side
Even in small areas, many species of moss and lichen can flourish

NPS Photo

A Forest on a Fencepost

With hundreds of species, mosses are found in abundance all over Olympic National Park. Varieties like the stair-step moss, cattail moss, spike mosses and club mosses, intertwine to become a diverse, albeit small, forest. Despite resembling other greenery, mosses are quite different from the rest of the forest’s undergrowth. This is because mosses are non-vascular, meaning they lack certain specialized tissues used for transporting water throughout their bodies. Unlike the ferns that also grow throughout the forest floor, mosses do not have true leaves, stems, or roots. Regardless of their primitive structure, the lack of these systems allows mosses to be able to grow just about anywhere throughout these forests. The sheer volume of moss growing in Olympic’s rainforests also provides for other plants.

Just as important to the forest are the assorted lichens that can be found hanging from high limbs. Individuals like Old Man's Beard and Witch's Hair are given their descriptive names by their draping, curtain-like nature. However, this "hanging moss" is not actually a moss. It's not a plant at all! While looking at these spectacular formations, visitors are actually seeing two separate organisms working as one. Lichens are composed of fungi living in a symbiotic relationship with green algae or cyanobacteria. The fungus provides the structure while the algae provides the nutrition via photosynthesis.

 
Resembling small, leafy ferns, stair-step moss grows in a clump
Just one of many varieties, Stair-Step Moss earns its name by growing on top of the previous year's growth

NPS Photo

A Moist & Mossy Land

Mosses not only lack true leaves, stems, and roots, but they also lack the protective outer cuticle most other plants have. Without this waxy film, they lose moisture and can dry out very quickly. Fortunately, the rainforests of Olympic are very soggy, receiving an average of 138 inches (3.5 meters) annually. This constant moisture provides ample habitat for not only mosses, but the lichens, lungwort, and liverworts as well.

You need not only look at the ground to find these unique organisms, either. While the goliaths of the forest rise like Roman columns to support the emerald canopy of needles above, they also support a lush drapery of hanging mosses and lichens among their lower branches. This is due not only to the formidable rainfall, but also to the dense fog that often blankets the forest as the rain and dew turns into low clouds. The moss takes in this moisture directly via osmosis.

 
Sunlight shines through a draping sleeve of moss hanging off of a branch with green ferns growing on top
Draping moss and lichen hanging from tree limbs allows for ferns to grow high above our heads

NPS Photo

Forests Above and Below

As mosses and lichens grow thick together, they start to resemble a soil, or substrate. As this happens, they can provide not only structure, but also water for other plants to survive and thrive on. When a tree falls in the forest, moss is often the pioneer that takes over the fresh log. As time goes on, seeds fall from above and land in this thick substrate, eventually taking root. The fallen tree has officially become a nursery log for other saplings and ferns to grow upon.


Of course, moss does not just grow on fallen logs, but it clings to living trees as well. This can still provide soil and structure for other greenery to plant themselves in. For this reason, hikers may see not only hanging lichen and mosses, but ferns growing above their heads, too. Plants that grow on other plants are called epiphytes. Even tree seeds can start their lives on other living trees high above. While these saplings begin their lives by taking root in the mosses and barks of the giants, they do eventually need to grow their roots downwards to the ground in order to tether and support their weight as they grow larger. This means they are not truly epiphytic, but thanks to the soil that mosses provide, they have the chance to grow in an already crowded forest.

Last updated: September 29, 2020

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