Leaves large, fern-like.
Sporanges in a spike or panicle above the sterile leaf.
=Ophioglossaceæ.=
Sporanges borne in sori, on the backs or margins of the leaves.
=Polypodiaceæ.=
Leaves small, reduced to scales.
Stems erect, hollow, jointed, rush-like; leaves reduced to
sheaths at the joints; sporanges in the terminal, cone-like
spike. =Equisetaceæ.=
Stems not hollow, creeping; leaves numerous, scale-like;
sporanges of one kind, solitary in the axils of the leaves.
=Lycopodiaceæ.=
Stems creeping, moss-like; leaves numerous; sporanges of two
kinds in the axils of the upper leaves, which are formed into
a quadrangular spike. =Selaginellaceæ.=