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Psilotum nudum, the whisk fern, [3] is a fernlike plant. Like the other species in the order Psilotales, it lacks roots. [4]Its name, Psilotum nudum, means "bare naked" in Latin, because it lacks (or seems to lack) most of the organs of typical vascular plants, as a result of evolutionary reduction.
Psilotum is a genus of fern-like vascular plants.It is one of two genera in the family Psilotaceae commonly known as whisk ferns, 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.
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 .
The fern crown group, consisting of the leptosporangiates and eusporangiates, is estimated to have originated in the late Silurian period 423.2 million years ago, [4] but Polypodiales, the group that makes up 80% of living fern diversity, did not appear and diversify until the Cretaceous, contemporaneous with the rise of flowering plants that ...
This subclass consists of the ferns commonly known as whisk ferns, grape ferns, adder's-tongues and moonworts. It is equivalent to the class Psilotopsida in previous treatments, including Smith et al. (2006). [2] The subclass contains two orders, Psilotales and Ophioglossales, whose relationship was only confirmed by molecular phylogenetic studies.
There are four extant eusporangiate fern families, distributed among three classes. Each family is assigned to its own order. [1] [2] Class Psilotopsida. Order Psilotales, family Psilotaceae – Whisk ferns (2 genera, about 17 species) Order Ophioglossales, family Ophioglossaceae – Adder's-tongues (5 genera, about 80 species) Class Equisetopsida
Class Lycopodiopsida, clubmosses and related plants (fern-allies) Class Sphenopsida or Equisetopsida, horsetails and scouring-rushes (fern-allies) Class Psilotopsida, whisk ferns (fern-allies) Class Filices or Pteropsida, true ferns (including leptosporangiates, marattioids, adder's-tongues, and moonworts)
Below are lists of extant fern families and subfamilies using the classification scheme proposed by the Pteridophyte Phylogeny Group in 2016 (PPG I). [1] The scheme is based on molecular phylogenetic studies, and also draws on earlier classifications, [1] particularly those by Smith et al. (2006), [2] Chase and Reveal (2009), [3] and Christenhusz et al. (2011). [4]