This group contains only two extant genera, and we cover just one of the these- Psilotum. Psilotum is native to tropical and subtropical regions. It grows from an underground rhizome, which produces dichotomously branching aerial stems. Sporangia appear along the sides of aerial stems. The life cycle is homosporous - only one kind of spore is produced.
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.