More About Mosses

November 6th, 2023

This time of the year the Bryophytes begin to shine. Mosses, liverworts, and hornworts are all around us! Liverworts and mosses can get confused while the hornworts are quite distinctive. This blog will be about mosses and their role in the ecosystem. The oak woodland on the upland area of the Willits Bypass Mitigation Lands, which we call Plasma, has many species of mosses growing on the oaks, ash, and bay trees. Going there after the last few rainstorms is delightful with the deep greens of the moss growing up the trunks of the trees and on the stumps and fallen logs.

The best way to identify mosses is to use a good hand lens or close-up binoculars, though there are species that become recognizable by learning the larger morphological characteristics and substrates that are preferred habitats. If you look with a hand lens you see that the capsules, or sporophytes, are located on short side branches and are highly visible. This placement of the capsules and being somewhat prostrate, matted, and highly branched is called pleurocarpous. This is one of the two forms of moss growth. The other is called acrocarpous, and these mosses are erect, tufted, and sparingly branched, with capsules found on the tips of their stems. This differentiation between the two groups is helpful in keying out a species, as the first question in a key is, “Is it pleurocarpous or is it acrocarpous?”

The hand lens also allows you to see each leaf of the moss and determine the shape and whether a midrib (called a costa), is present. These are important diagnostic characteristics for figuring out what species it is. These are characteristics that help narrow down the species. There are about 600+ known species of moss in California.

The book, California Mosses by Bill and Nancy Malcolm, Jim Shevock, and Dan Norris, has been my guide along with attending a few moss conferences over the past few years. In the introduction to the book, the authors state “California’s mosses are widespread, yet they are seldom studied or even noticed by the state’s many botanists. …. mosses are truly remarkable, able to survive desiccation that would quickly kill even the hardiest vascular plants…”

Taking a close look at a Valley Oak, Quercus lobata, I see a variety of mosses. The largest and most prominent species is called Tree or Fern moss, Dendroalsia abietica. This is an endemic and monospecific species to the Pacific Coast. This moss is found mostly on tree bark but can grow on rock walls. Each branch looks like a small tree or fern but during dry conditions they curve and fold downward protecting the capsules. This moss does not need a hand lens as it is easily identified and commonly found in our area.

Neckera moss, Neckera menziesii, is another large pleurocarpous and beautiful moss often found with Tree moss.It has shiny bright green undulate leaves and a prominent costa that reaches up past the middle of the leaf. It is a wonderful plant to look at under the dissecting scope because of its wavy iridescent green colors. Near the bottom of an oak tree, I find small round clumps of an acrocarpous moss with many leaf tips that are broken off. This is easy to see with a hand lens. It is the Broken leaf tip moss, Orthodicranum tauricum, an emerald-green, densely tufted moss that often grows with another compact acrocarpous moss on logs and stumps, Dicranoweissia cirrata. This mossoftengrows in small circular cushions and is easy to pick out. In the oak woodland, I also find this moss on the top of old wooden fence posts.

Mosses are nonvascular plants that use spores for reproduction instead of seeds and don’t grow flowers or true roots. They can buffer temperature and moisture in the soil and many mosses harbor cyanobacteria that convert atmospheric nitrogen into a form that can be taken up by vascular plants. Most mosses obtain their nutrients and water from the atmosphere, dust, and rainwater. They serve an important ecological function by moderating temperatures in the Arctic by keeping the ice from thawing rapidly. In warm climates, mosses protect tree roots by shading and insulating the soil from high temperatures. Look around wherever you live, and you will see there are many species of mosses on all types of surfaces from sidewalks to metal bridges. With a hand lens or close-up binoculars, you will be astounded by the variety of these interesting plants.