For Devonian palaeobotany, Australia represents one of the most geologically well-documented areas of the understudied Gondwana palaeocontinent. Despite this asset, the Australian plant record is still insufficiently known for this period. This situation is detrimental to a satisfactory understanding of the evolution and diversification patterns of vascular plants at a crucial moment in Earth’s history, when they acquired modern attributes and when the main extant lineages originated.This paper documents a plant assemblage from a locality near the town of Gooloogong in central New South Wales, based on fossils collected in 1973 (A. Ritchie, R. Jones, Australian Museum), and by our team in 2004. Fossils are preserved in the form of casts, adpressions preserving external morphology, and permineralizations showing internal anatomy. The Lycopsida are represented by Leptophloeum rhombicum, the Cladoxylopsida by Denglongia cf. hubeiensis, and the Progymnospermopsida by various organs attributed to the Archaeopteridales, i.e., a root of Callixylon sp., branches of Archaeopteris sp., and a leaf of Archaeopteris macilenta.This association, which is typical of the Frasnian of South China, supports a Frasnian age for the Gooloogong plant assemblage. It also confirms the existence of floristic exchanges between the northeastern part of Gondwana and South China at this time, and supports a trend towards the homogeneization of floras during the Late Devonian.

The poor sampling of Late Devonian fossils in Gondwana prevents a full understanding of the diversification patterns of the main vascular plant groups that are ancestral to extant lineages, such as the different pteridophyte-grade lineages. Among these are the Iridopteridales, a group with architectural features comparable to those of the sphenophytes. The Famennian locality of Barraba in New South Wales has yielded a diverse plant assemblage, among which Keraphyton represents the first iridopterid genus recorded in Australia. In this paper, two anatomically preserved fragments of axes from Barraba are assigned to a new species of Keraphyton, K. talentii, and an emended diagnosis of this Australian genus is provided. The axes of K. talentii differ from K. mawsoniae in their smaller size, a primary vascular system organized around three fundamental ribs connected centrally, instead of four in K. mawsoniae, and a smaller number of ultimate ribs. The aerenchymatous cortex observed in some parts of K. talentii suggests that this species was able to live in temporarily, if not permanently, wet habitats. Keraphyton axes are characterized by a deeply lobed stele with a complex pattern of dissection, and protoxylem strands that tend to be exarch. The larger size of K. mawsoniae is associated with a higher number of primary xylem ribs, but the primary vascular system remains actinostelic and is not associated with the development of radially aligned tracheids. The new species increases the taxonomic diversity of the free-sporing plants that were already predominant in the permineralized plant assemblage of Barraba.

The Middle Devonian is a transitional period for the first vascular plants, which acquire modern vegetative and reproductive structures, diversify considerably and, within the euphyllophytes, evolve the first representatives of modern plant groups, the monilophytes and lignophytes. However, the dynamics of this diversification across the different paleocontinents remains obscure, particularly within Gondwana. The upper Givetian locality of Oum el Jerane, in southeastern Morocco, has yielded a new assemblage of anatomically preserved plant remains whose description contributes to a better understanding of the floras of the northern margin of Gondwana during the Middle Devonian. The euphyllophytes include one iridopterid, Arachnoxylon minor, two cladoxylopsids, one of which represents the new genus Jerana, and two aneurophytales affiliated with the genus Triloboxylon. The cladoxylopsid remains from Oum el Jerane correspond to relatively small plants compared to the well-known coeval cladoxylopsids of Laurussia. Compared to the taxonomic composition of the four phytochoria recently defined for the Middle Devonian, the Oum el Jerane plant assemblage corresponds to the ‘subtropical’ phytochorion, which is close to the ‘Laurussia’ phytochorion, but which would correspond to drier environmental conditions.

The first anatomically preserved wood specimens of an upland Carboniferous flora from the Iberian Peninsula are reported from the Erillcastell Basin (Eastern Pyrenees, Catalonia, Spain). Two taxa are described, a calamitacean Equisetales (Arthropitys sp.) and a Cordaitales (Dadoxylon sp.). The Arthropitys specimen has fusiform multiseriate rays composed of square parenchyma cells with conspicuous uniseriate or multiseriate simple pits. These pits are located near the transverse walls and occasionally in the tangential walls. The tracheids vary in lumen size, with scalariform‐bordered pits on their radial walls and multiseriate pits in their cross‐field areas. The Dadoxylon specimen commonly has uniseriate fusiform rays. The tracheids are long, with a square shape in transverse section. Their radial walls bear araucarian pitting with a uniseriate to triseriate arrangement. The pits are circular with a spindle‐shaped aperture. Comparison of the Erillcastell specimens with coeval species from Europe indicates that they could belong to new species. The good preservation of the new fossil wood yields significant palaeoenvironmental information. The lack of marked growth rings in both specimens and the presence of tyloses in Dadoxylon suggest that the climate in the intramontane basins of the Pyrenees was slightly seasonal towards the end of the Carboniferous. This contrasts with the marked seasonality of coeval lowland basins. Such upland habitats may have enhanced the survival of plants adapted to humid conditions in a global context of increasing aridity.

Tyloses are protoplasmic swellings of parenchyma cells into the lumen of adjacent conducting cells. They develop as part of the heartwood formation process, or in response to embolism or pathogen infection. Here, we report the oldest fossil evidence to date of tylosis formation that occurs in permineralized wood of the (pro)gymnosperm Dameria hueberi from the Tournaisian (lower Mississippian, ca. 350 Ma) of Australia. Different developmental stages of tylosis formation are recognizable that range from small bubble-like protrusions to dense tyloses entirely filling the lumen of the conducting cells. The trigger for the development of tyloses in D. hueberi remains unknown. A survey of the fossil record of tyloses shows their occurrence in most groups of vascular plants since the Carboniferous. Future research in this field will screen even older (Devonian) fossils for evidence of tyloses and aim to understand the roles these structures have had in plant-pathogen interactions and plant hydraulic properties in the past.

ABSTRACT Tyloses are protoplasmic swellings of parenchyma cells into the lumen of adjacent conducting cells. They develop as part of the heartwood formation process, or in response to embolism or pathogen infection. Here, we report the oldest fossil evidence to date of tylosis formation that occurs in permineralized wood of the (pro)gymnosperm Dameria hueberi from the Tournaisian (lower Mississippian, ca. 350 Ma) of Australia. Different developmental stages of tylosis formation are recognizable that range from small bubble-like protrusions to dense tyloses entirely filling the lumen of the conducting cells. The trigger for the development of tyloses in D. hueberi remains unknown. A survey of the fossil record of tyloses shows their occurrence in most groups of vascular plants since the Carboniferous. Future research in this field will screen even older (Devonian) fossils for evidence of tyloses and aim to understand the roles these structures have had in plant–pathogen interactions and plant hydraulic properties in the past.

Gondwanan floras of Late Devonian age are poorly known. In Australia, the rare studies that have been published on Late Devonian plants are old and need reinvestigation. This paper is an account of the plant macro- and micro-remains found in the Mandowa Mudstone at Barraba, New South Wales. According to the miospores, plants are late to latest Famennian in age. The record of anatomically preserved specimens is diversified, with nine taxa assigned to the Lycopsida, Cladoxylopsida, Iridopteridales and Archaeopteridales. One specimen is referrable to the spermatophytes. Several taxa are specific to Barraba, i.e., the lycopsid genera Cymastrobus and Lycaugea, the iridopteridalean genus Keraphyton, the cladoxylopsid species Polyxylon australe, and possibly a plant represented by a large Hierogramma branch showing exarch protoxylem strands. The adpression record is dominated by axes of the cosmopolitan lycopsid genus Leptophloeum. It also includes specimens interpreted as seed plants such as a possible ovule resembling Pseudosporogonites, and two types of foliage differing by their petiole width. One of this foliage consists of delicate fronds broadly comparable to those of Cosmosperma. The closest flora from Barraba is the late Famennian–earliest Tournaisian flora of the New Albany Shale in eastern USA, suggesting floral connexion and comparable environmental conditions between Northern Gondwana and Southern Laurussia.

The Devonian-Carboniferous boundary (359 Ma) is now recognized as a period of major environmental changes, affecting both marine and terrestrial ecosystems. However, the impact of this event on plants remains controversial, notably because of the scarcity of macrofloral data in the earliest Carboniferous. In this context, we are currently focusing on the diversity and biology of fossil plants from the Tournaisian Lydienne Formation in the Montagne Noire, Southern France (Galtier et al. 1988). A first source of information is the (re)investigation of specimens kept in the Universite de Montpellier collections. This allows us to better understand plant systematic and functional diversity, and to compare the assemblage to Late Devonian floras from around the world. We will present some recent work on two key anatomically preserved taxa: (1) Cladoxylon, the youngest representative of the cladoxylopsids and the only one to date in which the production of periderm is documented (Decombeix & Galtier, 2021; Fig 1a), (2) large bisporangiate lycopsid cones originally described as Lepidostrobus (Zeiller, 1911; Bohm, 1935; Genson, 1941; Fig 1b) In addition to collection material, new trenches cutting through the Lydienne Formation at the locality of La Serre (Fig 1c) have allowed us to collect new specimens, mostly preserved as adpressions. Although most of them are very fragmentary (1-2 cm), they are important as they provide crucial information on small structures that are less represented in the anatomically preserved material, such as seeds and foliage. In the coming years, the combination of paleobotanical studies in the Montagne Noire with work conducted in parallel on the vertebrate fossil record is expected to provide a better insight on ecosystem recovery patterns following the D-C boundary

Premise of research. Resolving the time and patterns of origination of the Isoetales that thrived in the wet habitats of the late Paleozoic and have extant representatives in the genus Isoetes requires a better understanding of their early members and precursors. Recent studies conducted for a large part in South China acknowledged the diversification of Middle to Late Devonian taxa that possessed isoetalean traits and either were closely related to the Isoetales or occupied a basal position within this plant order. Recent investigations of Late Devonian floras from Australia show that this area, on the northeastern edge of Gondwana, also yields taxa with combinations of characters unknown elsewhere. Methodology. The anatomy and external morphology of an anatomically preserved fragment of a lycopsid axis from the Famennian locality of Barraba, in New South Wales, are described. The new specimen is compared to lycopsid taxa on the basis of anatomically preserved specimens ranging from the Middle Devonian to the Late Carboniferous. Pivotal results. The Barraba specimen shows a new combination of characters consisting of a medullated protostele, three-zoned cortex with a wide middle cortex, homogeneous primary outer cortex, presumably deciduous leaves, and slightly protuberant widely spaced leaf bases. Leaf bases show a single large parichnos and are covered adaxially by a thick translucent layer. The specimen is interpreted as the distal branch of a new arborescent taxon, Lycaugea edieae. Taxa with the closest morphoanatomical characters, such as Wexfordia hookense, belong to the Isoetales and are found in deposits of Europe and the eastern United States. Conclusions. Lycaugea edieae is the third lycopsid taxon described from Barraba, which, to date, has yielded a majority of spore-producing plants. It increases the diversity of the early Isoetales around the Devonian-Carboniferous boundary. The Barraba flora is more similar to the contemporaneous flora in southern Laurussia than to that in China.

The medullosans represent a diverse group of pteridosperms that was widely distributed in forested landscapes of the late Paleozoic. These plants became widely known from the extensive tropical lowland basins of Euramerica, where they grew as slender plants with large fronds and fern-like foliage. Besides, there also exist medullosans of Late Pennsylvanian-early Permian intramontane basins of Central Europe, which have been out of research focus for more than a century. They had bigger stems with larger amounts of secondary xylem and a modified organisation of the vascular system. We provide an overviewon taxonomy, anatomy and palaeoecology of these medullosans from the most important fossil localities, encompassing Chemnitz (Germany), the type locality for most taxa, Autun (France), Nova Paka (Czech Republic) and others. Late Pennsylvanian-early Permian medullosans of intramontane basins were thriving under seasonally-dry palaeoclimate on wet clastic soils showing proximity to the groundwater level. In forested landscapes, they occurred mostly sub-ordinated as part of the forest understorey. The plants' architecture and taphonomical inferences point to a (semi-)self-supporting growth habit of most of the taxa presented here. Plant architectural and anatomical peculiarities suggest a high water-conducting potential of these plants, raising questions on their ecological role in early Permian habitats. Anatomical differences with tropical relatives of Carboniferous age might reflect an evolutionary process that was driven by environmental changes during the late Paleozoic. The unusual arrangement of their stem tissues addresses the question of their role in seed plant evolution, e.g., their potential relationship with cycads. (C) 2021 Elsevier B.V. All rights reserved.