The stem has a core of thick-walled protostele in its centre surrounded by an endodermis which regulates the flow of water and nutrients.

[6]The genus Psilotum was first formally described in 1801 by Olof Swartz and the description was published in Journal für die Botanik (Schrader).

The distribution of Psilotum is tropical and subtropical, in the New World, Asia, and the Pacific, with a few isolated populations in south-west Europe.

The highest latitudes known are in South Carolina, Cádiz province in Spain,[11] and southern Japan for P. nudum.

Psilotum superficially resembles certain extinct early vascular plants, such as the rhyniophytes and the trimerophyte genus Psilophyton.

The unusual features of Psilotum that suggest an affinity with early vascular plants include dichotomously branching sporophytes, aerial stems arising from horizontal rhizomes, a simple vascular cylinder, homosporous and terminal eusporangia and a lack of roots.