The lycophytes, when broadly circumscribed, are a group of vascular plants that include the clubmosses. They are sometimes placed in a division Lycopodiophyta or Lycophyta or in a subdivision Lycopodiophytina. They are one of the oldest lineages of extant (living) vascular plants; the group contains extinct plants that have been dated from the Silurian. Lycophytes were some of the dominating plant species of the Carboniferous period, and included the tree-like Lepidodendrales, some of which grew over 40 metres (130 ft) in height, although extant lycophytes are relatively small plants.
The zosterophylls are a group of extinct land plants that first appeared in the Silurian period. The taxon was first established by Banks in 1968 as the subdivision Zosterophyllophytina; they have since also been treated as the division Zosterophyllophyta or Zosterophyta and the class or plesion Zosterophyllopsida or Zosteropsida. They were among the first vascular plants in the fossil record, and had a world-wide distribution. They were probably stem-group lycophytes, forming a sister group to the ancestors of the living lycophytes. By the late Silurian a diverse assemblage of species existed, examples of which have been found fossilised in what is now Bathurst Island in Arctic Canada.
Crenaticaulis was an early genus of slender, dichotomously branching, leafless land plants, known from the Devonian period and first described in 1969. They were probably allied to the zosterophylls, and are assigned to subdivision Zosterophyllophytina, or class Zosterophyllopsida. They bore branches and scalariform tracheids.
Sawdonia is an extinct genus of early vascular plants, known from the Upper Silurian to the Lower Carboniferous. Sawdonia is best recognized by the large number of spikes (enations) covering the plant. These are vascular plants that do not have vascular systems in their enations. The first species of this genus 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." The holotype used for description is Dawson Collection Number 48, pro parte, Museum Specimen Number 3243. Sir J. William Dawson Collection, Peter Redpath Museum, McGill University, Montreal, Quebec, Canada.
Sartilmania is a genus of extinct vascular plants of the Early Devonian. Fossils were found on the Sart Tilman campus of the University of Liège, Belgium.
Hicklingia is a genus of extinct plants of the Middle Devonian. Compressed specimens were first described in 1923 from the Old Red Sandstone of Scotland. Initially the genus was placed in the "rhyniophytes", but this group is defined as having terminal sporangia, and later work showed that the sporangia of Hicklingia were lateral rather than strictly terminal, so that it is now regarded as having affinities with the zosterophylls.
Huia is a genus of extinct vascular plants of the Early Devonian. The genus was first described in 1985 based on fossil specimens from the Posongchong Formation, Wenshan district, Yunnan, China.
Adoketophyton is a genus of extinct vascular plants of the Early Devonian. The plant was first described in 1977 based on fossil specimens from the Posongchong Formation, Wenshan district, Yunnan, China. These were originally named Zosterophyllum subverticillatum; later the species was transferred to a new genus as Adoketophyton subverticillatum. One cladistic analysis suggested that it is a lycophyte, related to the zosterophylls. Other researchers regard its placement within the vascular plants as uncertain.
Discalis is a genus of extinct vascular plants of the Early Devonian. The name is derived from the Greek δίσκος, referring to the disc-shaped sporangia. The genus was first described by Hao in 1989 based on fossil specimens from the Posongchong Formation, Wenshan district, Yunnan, China.
Distichophytum is a genus of extinct vascular plants of the Late Silurian (Ludfordian) to Early Devonian (Emsian), around 426 to 393 million years ago. The genus has a tangled taxonomic history, also being known as Bucheria and Rebuchia.
Gosslingia was a genus of Early Devonian land plant with branching axes. Fossils have been from the Lochkovian to the Pragian, 419 to 408 million years ago.
Oricilla was a genus of Early Devonian land plant with branching axes. Fossils have been found from the Pragian to the Emsian.
Nothia was a genus of Early Devonian vascular plants whose fossils were found in the Rhynie chert in Scotland. It had branching horizontal underground stems (rhizomes) and leafless aerial stems (axes) bearing lateral and terminal spore-forming organs (sporangia). Its aerial stems were covered with small 'bumps' (emergences), each bearing a stoma. It is one of the best described early land plants. Its classification remains uncertain, although it has been treated as a zosterophyll. There is one species, Nothia aphylla.
Konioria was a genus of early land plant with branching axes. Known fossils are of Early Devonian age.
Danziella is a genus of extinct vascular plants of the Early Devonian. Fossils found in the Artois region of northern France were first described as Zosterophyllum artesianum, but a later review by Edwards showed that they did not fit the circumscription of that genus.
Wenshania is a genus of extinct vascular plants found in the Posongchong Formation, Yunnan, China, which is of Early Devonian age. Plants consisted of leafless stems with simple dichotomous branching, and bore spore-forming organs or sporangia all around the sides of stems. Wenshania is part of the broadly defined group of zosterophylls.
Demersatheca is a genus of extinct vascular plants of the Early Devonian. Fossils were first found in the Posongchong Formation of eastern Yunnan, China. The plant had smooth leafless stems at least 1 mm in diameter, but only regions which bore spore-forming organs or sporangia are well-known. Sporangia were borne in 'spikes' or strobili, at least 40 mm long; one had 32 sporangia. Sporangia were arranged in four rows, two sporangia being opposite to one another on the stem with the next two being at right angles. Each sporangium consisted of two 'valves' which opened at the top to release their spores. A particular feature of Demersatheca which distinguishes it from other zosterophylls is that the stalk-less sporangia were sunken into the stem of the spike, so that the outer valve was flush with the surface.
Macivera is a genus of extinct vascular plants. Fossils were found in sediments in Bathust Island, Nunavut, Canada, from the upper Silurian. The leafless stems (axes) branched dichotomously and were relatively thin, being between 0.7 and 1.0 mm wide. Spore-forming organs or sporangia, which were elliptical, being longer than wide, were borne on the end regions of stems. Macivera is considered to be a zosterophyll.
Gosslingiales is an order of extinct zosterophylls. The zosterophylls were among the first vascular plants in the fossil record, and share an ancestor with the living lycophytes. The group has been divided up in various ways. Hao and Xue in 2013 used the presence or absence of terminal sporangia as a major dividing feature. The order Zosterophyllales was used for species with terminal as well as lateral sporangia, which were considered to have determinate growth, with their sporangia generally being arranged in spikes. The paraphyletic order Gosslingiales was used for species without terminal sporangia, which were considered to have indeterminate growth, with fertile branches generally circinate. Species assignable to the Gosslingiales made up about 9% of all confirmed species in the Early Devonian flora.
The barinophytes are a group of extinct vascular plants (tracheophytes). Their relationship with other vascular plants is unclear. They have been treated as the separate class Barinophytopsida, the order Barinophytales of uncertain class and as a family or clade Barinophytaceae within the zosterophylls. They have also been considered to be possible lycopodiopsids.
