psilotum

Psilotum is a genus of fern-like vascular plants, commonly known as whisk ferns. It is one of two genera in the family Psilotaceae, the other being Tmesipteris. Plants in these two genera were once thought to be descended from the earliest surviving vascular plants, but more recent phylogenies place them as basal ferns, as a sister group to Ophioglossales. They lack true roots and leaves, the stems being the organs containing conducting tissue. There are only two species in Psilotum and a hybrid ...