fern-allies. Stem when monomorphic,
without vascular collenchyma, or dimorphic usually with vascular collenchyma, green in colour,
annually grown. Stem branched with superficial stomata and outer common
endodermis, branched with simple valleys having scattered stomata throughout
the channel valleys. Stomata in the
single or double line on each side. Branch sheaths distinctly furrowed.
Strobilous terminal on the main stem or at the end of the branches. Sporangia
unilocular. Spores spherical, green,