Psilotaceae
Psilotaceae is a family of ferns (class Polypodiopsida) consisting of two genera, Psilotum and Tmesipteris with about a dozen species. It is the only family in the order Psilotales. Description Once thought to be descendants of early vascular plants (the Psilophyta of the Devonian period), Psilotaceae have been shown by molecular phylogenetics to be ferns (Polypodiopsida), and a sister group of the Ophioglossaceae. The family contains two genera, Psilotum and Tmesipteris. The first genus, Psilotum, consists of small shrubby plants of the dry tropics commonly known as "whisk ferns". The other genus, Tmesipteris, is an epiphyte found in Australia, New Zealand, and New Caledonia. All members of Psilotaceae are vascular plants without any true roots. Rather, the plants are anchored by an underground system of rhizomes. The small, stem-like gametophytes of Psilotaceae are located in this rhizome system, and they aid in a plant's nutrient absorption through the soil. This is primarily achieved through saprotrophic feeding on organic soil matter and mycorrhizal interactions. Psilotaceae do not have leaves. Some species have leaf-like structures called enations which have no vascular tissue except for a small bundle at the base. These are almost peg-like, stubby and are generally not considered true leaves,