A family of Lycopsida within the Pteridophyta, with small, simple, usually narrow leaves, which clothe the forking stems or, as in Phylloglossum, arise from the base of the naked, unbranched stem. The stems bear sporangia in the axils of either normal or highly modified leaves, either along their length in alternating sterile and fertile zones, or (in most species) in clearly differentiated terminal cones. All sporangia are alike and contain numerous minute spores, which germinate to produce sexual gametophytes. Unlike Selaginellaceae, the leaves have no ligule on their upper side. The family is very ancient and similar plants have been found as fossils in Devonian and Carboniferous rocks. They are now usually divided into 5 genera, which contain some 450 species, some of which are cosmopolitan in distribution.
Subjects: Plant Sciences and Forestry.