I have always known them as princess pine and ground cedar, "the little trees" in our forest. They are perennial and evergreen and thus are perky all year round. These are the Lycopodiums or clubmosses, relatives of the ferns. There are a bunch of clubmosses in these parts, but the two I see most often are what I commonly call princess pine (also known as ground pine or tree clubmoss or Lycopodium obscurum) and ground cedar (L. complanatum).
Clubmosses are old, 300 million years old. The ancient clubmosses, horsetails, and ferns, formed the coal that we mine today. Clubmosses propagate by running and sometimes by leaping! They creep along below ground, sprouting little trees every few inches. These plants also reproduce by spores, which are borne on cones or strobili that stick up above the leaves.
To learn more about these enduring plants, you have to get down on the ground to be among this miniature forest. Imagine a chipmunk standing on its haunches and you will be about at the height of the Lycopodiums. Watch to see how far the little "pines" and "cedars" in your woods run each year.