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Psilophyton is a genus of extinct vascular plants. Described in 1859, it was one of the first fossil plants to be found which was of Devonian age (about 420 to 360 million years ago ). Specimens have been found in northern Maine , USA; Gaspé Bay , Quebec and New Brunswick , Canada; the Czech Republic ; and Yunnan , China.
Trimerophytopsida (or Trimeropsida) is a class of early vascular plants from the Devonian, informally called trimerophytes.It contains genera such as Psilophyton.This group is probably paraphyletic, and is believed to be the ancestral group from which both the ferns and seed plants evolved.
The class was established in 1917, under the name Psilophyta, with only three genera (Rhynia, Horneophyton and Psilophyton) [1] for a group of fossil plants from the Upper Silurian and Devonian periods which lack true roots and leaves, but have a vascular system within a branching cylindrical stem.
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.
Rhynia is a single-species genus of Devonian vascular plants. Rhynia gwynne-vaughanii was the sporophyte [2] generation of a vascular, axial, free-sporing diplohaplontic embryophytic land plant of the Early Devonian that had anatomical features more advanced than those of the bryophytes.
The first species of this genus (Sawdonia ornata) was described in 1859 by Sir J. William Dawson and, was originally attributed to the genus Psilophyton. He named this plant Psilophyton princeps. In 1971 Francis Hueber proposed a new genus for this species due to its "Divergent technical characters from the generic description for Psilophyton."
At first most of the fossilized early land plants other than bryophytes were placed in the class Psilophyta, established in 1917 by Kidston and Lang. [9] As additional fossils were discovered and described, it became apparent that the Psilophyta were not a homogeneous group of plants, and in 1975 Banks developed his earlier proposal to split it into three groups, which he put at the rank of ...
The identification of plant fossils in Cambrian strata is an uncertain area in the evolutionary history of plants because of the small and soft-bodied nature of these plants. It is also difficult in a fossil of this age to distinguish among various similar appearing groups with simple branching patterns, and not all of these groups are plants.