The Carboniferous (345 - 290 mya) was good to the clubmosses, at least, in Laurussia (Euramerica), the land that would become Greenland, Europe, and North America. Gondwana (Africa, India, Australia, South America and Antarctica) was stuck in the deep freeze over the South Pole, but Laurussia was a tropical lowland—warm and swampy.
Dragonflies had two-foot wingspans, millipedes were the size of large snakes, and the clubmosses were canopy trees up to 100 feet tall. Huge tree ferns and giant horsetails completed the community. The plants lay in the swamps where they fell, never fully decaying and covered by sediments until pried from the earth for energy. In hindsight, we call them the coal forests.
Somehow the clubmosses survived the Permian extinction 248 million years ago. Ninety percent of all species were erased. Certainly, the tree-sized lycopods did not make the cut, but a few of the smaller clubmosses did. Lycopods stayed through the rise of the dinosaurs and their fall with the Triassic extinction sixty-five million years ago. They adapted with the global cooling of the Miocene extinction and remained through the Pleistocene with its repetitive ice sheets.
Variously called running pine, wolf's claw clubmoss, staghorn clubmoss, or common clubmoss, Lycopodium clavatum Linnaeus is a circumboreal species at home on rocky slopes, thickets and brushland, and woodlands of temperate and subarctic zones of Europe, Asia, and North America. In summer, it is easily overlooked hidden among grasses. In winter, though, its tiny pine-like branches are often the only green ground cover. The plant is gone from parts of its historic range because the tiny evergreen was over-collected for winter decorations.
(Compiled from: "Division Lycophyta", Chapter 16, Seedless Vascular Plants, Biology of Plants, 5th Ed., P.H. Raven, R.F. Evert, and S.E. Eichhorn, Worth Publishers, 1992; "Lycopodium clavatum Linnaeus", Flora of North America, Vol. 2, eFloras.org,; and Paleobotany and the Evolution of Plants, 2nd Ed., W.N. Stewart and G.W. Rothwell, Cambridge University Press, 1993)
