You’ve discovered a tiny evergreen forest of what looks like diminutive hemlock or cedar trees, barely taller than a chipmunk. They’re spread across the cool shade cast by a canopy of hardwood or coniferous trees. This Lilliputian forest is actually a clump of clubmosses.
Clubmosses are among the oldest plants on Earth, having evolved over 390 million years ago. Long ago, clubmosses weren’t so diminutive. They were tree-like and towered over tropical forests, reaching 100 feet tall. Those ancient giants are long extinct but they continue to affect our environment; their remnants persist as fossil fuels.
Ironically, clubmosses are not mosses, although eighteenth century botanists thought they were. In the nineteenth century, botanists surmised that the clubmosses were closely related to ferns because they reproduce by spores and placed them in a category of plants called fern allies. That also was incorrect. Advanced technology and DNA sequencing have revealed that clubmosses evolved separately from ferns and are not closely related. However, clubmosses are still called fern allies or fern relatives in field guides.
There are about 15 species of clubmosses in New England, with several species being fairly common. Most grow in moist, shaded woodlands. All are evergreen and have tiny, narrow leaf-like structures called microphylls that grow in crowded rows around branched or unbranched upright stems. Most clubmosses spread via horizontal stems that are either below ground or at the soil surface. This vegetative spreading is the primary means of reproduction and gives rise to the name “running pine” for several species.
When clubmosses reproduce by spores, these are usually borne in cone-like structures atop the stems, called strobili. Some species have branched strobili that look like tiny antlers or candelabras. Other species, like our common shining clubmoss and fir clubmoss, bear spores in the axils of upper leaves. Copious miniscule yellow spores mature in late summer to autumn and are dispersed from the strobili by the faintest air currents. Only a tiny number of spores will develop into mature plants, and that process can take up to 20 years.
Clubmoss spores have a high oil content, making them both water repellent and highly flammable. People have used the spores in a variety of ways, especially those of Lycopodium clavatum (one of the running pines that is also called staghorn clubmoss or wolf’s claw clubmoss), which is common in many parts of the world. Spores were ignited to provide the flash in early photography as well as pyrotechnic effects in theatrical productions and movies. Clubmoss spores are also used in science classes to demonstrate the principles of combustion.
The spores’ water repellency has made them popular for use as pill coatings, soothing skin powders, makeup, and non-stick dustings for surgical gloves and condoms. Their uniform, miniscule size has aided in making microscopic measurements.
Clubmoss plants themselves also have commercial value. The attractive evergreen stems have long been harvested for use as winter seasonal decorations and in floral displays. The tree clubmosses, including prickly tree clubmoss and princess pine, are especially popular—so much that there’s concern about unsustainable harvesting. National forests allow harvesting of tree clubmosses by permit only.
Humans aren’t the only creatures that benefit from these tiny plants. Clubmoss clumps provide protective nesting sites for ground-nesting birds, including hermit thrushes and ovenbirds. A recent study found that the presence of tree clubmosses at nest sites significantly increased ovenbird nest survival rates.
Clubmosses contain alkaloids that make them unpalatable to deer, so they have not suffered from overbrowsing. But in some places, their populations have been adversely affected by the actions of non-native earthworms, which break down the duff layer on the forest floor, thereby changing soil composition and reducing the availability of nutrients.
Overharvesting, non-native earthworm invasion, and habitat destruction have resulted in clubmosses being less abundant than they once were. Careful forest stewardship can help to preserve these ancient inhabitants of the Earth.
By Edna Greig