Gametophytes are tiny, subterranean, heterotrophic, and grow with the aid of symbiotic fungi. Microphylls probably evolved from prophylls that became vascularized with a simple leaf trace. They have a single vein and no leaf gap. The life cycle is basically similar to that of Psilotum, but may be homosporous or heterosporous. Although heterospory is rare among vascular cryptogams, all seed plants are heterosporous.
Heterosporous plants produce microspores and megaspores.
We discussed two of the five genera classified in the division. Its aerial stems are distinctive with their whorled leaves, which gives the stem a jointed appearance. The leaves are tiny, making the stem appear leafless. Horsetails are homosporous. Sporangia are borne on sporangiophores clustered in strobili.