Psilophytopsida

As Urfarne ( Psilophytopsida; Greek hallucinogen = " naked, bare " ) sometimes the original groups of vascular plants are summarized.

It is the most primitive group of vascular cryptogams, with Urtelomen, entirely smooth or with emergences, with proto- or Actinostele. Real roots were. The sporangia were individually and terminal or arranged in spikes, with a multi-layer sporangium, they were isospor. They formed about 420 million years ago, in Ludfordium at the transition from Silurian to Devonian, and were already extinct again in the Upper Devonian.

Since the Urfarne are not more closely related to each other, they were later divided among the three clans Rhyniophyta, Trimerophytophyta and Zosterophyllophyta.