Moss Habitats

Moss, which is a bryophyte, is a nonvascular green plant that comes in two primary life forms:  an upright plant, like the diagram to the right, and a spreading plant.  Having no tissues for the transport of water or nutrients, mosses absorb what they need directly through their leaves and have no roots for storage.

Moss reproduction is beautiful.  Mosses produce tiny, tiny little spores that mature in capsules on the ends of stalks and are wind dispersed upon maturity.  Moss taxonomy can be hell; some species can only be determined by dissecting these spores under the microscope!

Mosses are able to tolerate great extremes of temperature and moisture, and hence live in a tremendous diversity of habitats throughout the world.  Desert mosses such as these tolerate long periods of dehydration, and then spring to life with a few drops of water.  (Oregon's High Desert)

Whereas riparian species such as these are so accustomed to water that they perish quickly if they become too dry. (Oregon's Coast Range left, Cascades right)

It's true that moss volumes are greatest on the boles of hardwood trees, but epiphytic moss is ubiquitous in the Pacific Northwest, delicately draping conifers as well.

My favorite places are those in which moss carpets the ground, flows over logs and shrubs, and hangs from the canopy in a plethora of vibrant, living greens (preferably dripping wet!).  Old growth Douglas-fir forests often have just the right light and moisture conditions to create this exact scene.

(H.J. Andrews Experimental Forest, Oregon Cascade Range)

Here are some of the most common and abundant species you would find if you were in that old-growth stand.  Hylocomium splendens, the stair-step moss, nearly competes with the vascular understory in height and breadth as it climbs its way toward the sun.  Hypnum circinale is the most prevalent moss on Douglas-fir and western hemlock bark in Oregon.  Forming long, skinny strands, it slowly and persistently weaves a vertical carpet on tree boles.  Eurhynchium oreganum, the Oregon feather moss (pale yellow- green) and Dicranum scoparium (dark green) can be found on the forest floor and downed woody debris throughout western Oregon.

Colonizing rock outcrops, particularly in eastern Oregon where these were captured, are various species of Racomitrium (there are three above, left), while the forest floor in higher elevation sites is guaranteed to support colonies of Polytrichum juniperinum, such as this one from arctic Alaska (near Kotzebue).

There's something especially appealing about bog mosses, such as these Sphagnum (left and the red ones under the green Polytrichum at the right) in New Hampshire.

Amazingly, some places are virtually mossless (the horror!).  This dense stand of Douglas fir in the northern Oregon Cascades is so dark in the understory that virtually nothing green is to be found, except the ubiquitous vine maple; similar stands occur in the Coast Range as well (below).