Greek lykos, wolf,+ podos, foot, alluding to the branch tips of the type species of the genus Lycopodium resembling a wolf's paw.

Plants epiphytic or terrestrial. Stems erect, pendent, or trailing, unbranched to highly dichot-omously branched. Leaves small, simple, needle-or lancelike, 1-veined, spirally arranged, or arranged in rows. Strobili, if present, sessile or stalked. Sporangia borne on specialized leaves of terminal strobili, or in axils of vegetative leaves. Sporangia 2-valved, reniform or globose.

Here treated as comprising four genera and about 400 species, the family is of worldwide distribution. Most common in mid-to high-elevation habitats in the Tropics, but present in temperate and boreal areas. Represented in Hawai'i by three genera.

The monophyletic family Lycopodiaceae is treated as one genus or divided into subfamilies, genera, subgenera, or groups by various authors. The recognition of genera within this family is subject to debate. In the past all species in the family Lycopodiaceae were placed in the single genus Lycopodium. In recent decades it has been recognized that to be consistent with the treatment of the ferns, a few to several genera must be recognized for the Lycopodiaceae. (Fewer differences separate the fern genera Arachniodes, Ctenitis, Cyrtomium, Dryopteris, Nothoperanema, Polystichum, and Tectaria, for example, than those separating the lycopod genera recognized here.) In the last several decades, Lycopodiaceae has been variously divided into two families, three subfamilies, seven subgenera, and into two to seven genera. In this book 0llgaard's (1987) treatment is followed, and three genera are recognized.