Selaginella occurs mostly in the tropical regions of the world, with a handful of species to be found in the arctic-alpine zones of both hemispheres.

[2] Fossils assignable to the modern genus are known spanning over 300 million years from the Late Carboniferous to the present.

[3] Selaginella species are creeping or ascendant plants with simple, scale-like leaves (microphylls) on branching stems from which roots also arise.

[citation needed] The steles are connected with the cortex by means of many tube-like structures called trabeculae, which are modified endodermal cells with casparian strips on their lateral walls.

[citation needed] In Selaginella, each microphyll and sporophyll has a small scale-like outgrowth called a ligule at the base of the upper surface.

In this state, they may roll up into brown balls and be uprooted, but can rehydrate under moist conditions, become green again and resume growth.

[9][jargon] Their chloroplasts are missing about two-thirds of their plastidial tRNA genes, which are instead found in the genome of the nucleus.

[citation needed] The first major attempt to define and subdivide the group was by Palisot de Beauvois[14] in 1803–1805.

[21] They show a wide range of characters; the genus is overdue for a revision which might include subdivision into several genera.

[citation needed] Species of spikemoss include: A few species of Selaginella are desert plants known as "resurrection plants", because they curl up in a tight, brown or reddish ball during dry times, and uncurl and turn green in the presence of moisture.