Friday, March 2, 2007
There are about 100 species of Lycopodium worldwide and 11 in northeast and central North America. All members of the genus are called clubmosses and are also widely known as Running Pines or Ground Pines since they look like tiny pine trees and commonly propagate by runners. Those of you with an active imagination may accept that the tips of the branches of some species resemble a wolf's paw.
When and where found. The clubmosses are evergreen and easy to spot in the winter either sticking up through the snow or in contrast to the brown leaf litter throughout the woods. The Shining Clubmoss is not as common in Carlisle as some of the other clubmosses but Tom Brownrigg's keen eye spotted a clump beside the path connecting Bellows Hill Road and the Rockstrom Trail. It is growing in its typical habitat along a stream.
Distinguishing characteristics. The Shining Clubmoss has erect stems about six inches tall densely covered with shiny green leaves. At first glance you could mistake it for a rather tall moss. The leaves spread out around the stem in the manner of a bottle-brush — or maybe better a test-tube brush. Unlike the more common clubmosses, the Shining Clubmoss does not have the elongated spore-bearing cones that rise above the top leaves. Instead it has kidney-shaped spore cases located down in the axils of the upper leaves. This is a characteristic thought to represent a more ancient stage in evolution.
Evolution. Fossil records of clubmosses show that they existed 300 million years ago in the Paleozoic Era. Today's clubmosses are the evolutionary survivors of giant clubmoss trees which were part of large jungles that became seams of coal. Clubmosses are a step up from mosses and liverworts and are most closely related to the ferns which, along with the clubmosses, represent the first true vascular plants, i.e., they have xylem and phloem tissue for transporting water and nutrients and for the structural support needed for taller growth. Flowering plants are a further step-up, physically and developmentally. They differ from the lower plants in reproducing by seeds. The success is measured in over 200,000 species of trees, shrubs, grasses and other flowering plants. By comparison, there are about 10,000 species of ferns and clubmosses.
Life cycle. There are two distinct stages or generations in the life cycle of a clubmoss. Each begins with a certain type of reproductive cell and each produces a different type of reproductive cell that is responsible for the next generation. The asexual spore-producing generation, the sporophyte, is the plant we see in the woods. The spores develop over a period of seven or more years into tiny gametophytes with sperm and egg producing organs. The fertilized eggs take another ten or so years to grow into the next generation sporophyte and complete the life cycle. The Shining Clubmoss, like many other clubmosses, also spreads vegatatively from runners.
Spores. The spores are so very tiny and uniform in size they were once used for microscopic measurement. Their fineness and smoothness made them useful for coating pills. If lit, they result in a flash explosion and so have been used in fireworks and for photography flashes. Clubmoss spores are produced in such prodigious volumes that commercial uses were possible. In the warm weather earlier this winter, I was sending up clouds of clubmoss spores along the Acorn Trail at Great Brook Farm just by brushing the plants as I walked through them. (These were the more common clubmosses with the spore-bearing cones.)
References. Peterson Field Guide to Ferns by Boughton Cobb.
© 2007 The Carlisle Mosquito