Documented evidence of fungi associated with Mesozoic ferns is exceedingly rare. Three different types of fungal remains occur in a portion of a small, permineralised fern stem of uncertain systematic affinities from the Triassic of Germany. Exquisite preservation of all internal tissues made it possible to map the spatial distribution of the fungi in several longitudinal and transverse sections. Narrow, intracellular hyphae extend through the entire cortex, while wide hyphae are concentrated in the cortical intercellular system adjacent to the stele and leaf traces. Hyphal swellings occur in the phloem and adjacent cortex, while moniliform hyphae (or chains of conidia) are present exclusively in parenchyma adjacent to the stele. No host response is recognisable, but host tissue preservation suggests that the fern was alive during fungal colonisation. The highest concentration of fungal remains occurs close to the stele and leaf traces, suggesting that the fungi either utilised the vascular tissues as an infection/colonisation pathway or extracted nutrients from these tissues. This study presents the first depiction of fungal distribution throughout a larger portion of a fossil plant. Although distribution maps are useful tools in assessing fungal associations in relatively small, fossil plants, preparing similar maps for larger and more complex fossils would certainly be difficult and extremely arduous.

Nanowires with different nitrogen concentrations were grown by Metal-Organic Chemical Vapor Deposition (MOCVD) using DEZn, N2O and NH3as zinc, oxygen and nitrogen doping sources respectively. Low temperature photoluminescence, Raman spectroscopy and Transmission Electron Microscopy are combined to study the incorporation of nitrogen in the wires. The observation of donor-acceptor pair band confirms that the incorporation nitrogen in ZnO nanowires is responsible for the creation of acceptor centers. The additional peaks observed in Raman are correlated to nano-sized inter-atomic distance fluctuations observed in TEM. These domains combined with a resonance effect are probably the explanation of the huge Raman cross section observed for the impurity related peaks.

Abundant charcoalified seed fern (pteridosperm) pollen organs and ovules have been recovered from Late Viséan (Mississippian 330 Ma) limestones from Kingswood, Fife, Scotland. To overcome limitations of data collection from these tiny, sometimes unique, fossils, we have combined low vacuum scanning electron microscopy on uncoated specimens with backscatter detector and synchrotron radiation X-ray tomographic microscopy utilizing the Materials Science and TOMCAT beamlines at the Swiss Light Source of the Paul Scherrer Institut. In combination these techniques improve upon traditional cellulose acetate peel sectioning because they enable study of external morphology and internal anatomy in multiple planes of section on a single specimen that is retained intact. The pollen organ Melissiotheca shows a basal parenchymatous cushion bearing more than 100 sporangia on the distal face. Digital sections show the occurrence of pollen in some sporangia. The described ovule is new and has eight integumentary lobes that are covered in spirally arranged glandular hairs. Virtual longitudinal sections reveal the lobes are free above the pollen chamber. Results are applied in taxonomy and will subsequently contribute to our understanding of the former diversity and evolution of ovules, seeds, and pollen organs in the seed ferns, the first seed-bearing plants to conquer the land.

Le défaut de fatigue de contact des rails dénommé "head-check" comporte après amorçage une phase de propagation en mode II débouchant soit sur une bifurcation fatale, soit sur un blocage de la fissure. Pour prévoir au cas par cas les conditions qui peuvent conduire à l'une de ces issues, une modélisation de la fissuration en mode II est nécessaire. Dans cette étude, nous montrons que la méthode des dislocations est idéale pour établir les ΔKII qui permettent de décrire le comportement de la fissure en utilisant les paramètres de la loi de Paris. Nous analysons ainsi notamment l'effet de proximité dans le cas de paires de fissures, le rôle du frottement entre les faces de celles-ci et sa synergie avec les contraintes résiduelles.

A new permineralized fossil plant assemblage is described from volcaniclastic tuff collected in the Upper Permian (Wuchiapigian to Changhsingian) Xuanwei Formation at Shanjiaoshu mine, Guizhou Province, China. The assemblage is fragmentary but contains a small sphenopsid strobilus, a partial strobilus of a lepidodendralean lycopsid, pinnae of the filicalean fern Anachoropteris and a filicalean non-laminate fertile pinna rachis, the marattialean ferns Eoangiopteris, Scolecopteris and Psaronius, hooked stems of probable gigantopterid affinity, and two kinds of cardiocarpalean ovules. This represents the first indisputable evidence of Anachoropteris from the Permian of China, and contrasts with previous evidence from Europe and North America that indicates this genus became extinct during earliest Permian times. The assemblage highlights the persistence of plants from wetland communities and mire ecosystems into the Upper Permian of southern China, and adds further support to the presence of the Ameriosinian phytogeographical realm. This represents the first record of a plant assemblage preserved in volcaniclastic sediments from the Upper Permian of southern China, and in combination with other recently discovered plant assemblages in similar deposits in southern China, suggests volcanism to be an important factor in facilitating permineralized plant preservation in this realm. Although the source of the volcanism that produced the tuff is unknown, its age and location are consistent with the Emishan Large Igneous Province (LIP) of southwest China.

Permineralised material of Rhacopteris lindseaeformis (Bunbury) Kidston and Spathulopteris obovata (Lindley & Hutton) Kidston, showing both external morphology and excellent anatomical preservation, is described from the Lower Carboniferous (?Asbian, Upper Viséan) tuffs and dolomitic ashes outcropping at Weaklaw–Gullane, East Lothian, Scotland. These specimens provide the first anatomical information on these two well-known plant compression genera. The rachises have Lyginorachis-type anatomy with distinctive characters in the two species. Spathulopteris rachises correspond to Lyginorachis kingswoodense Meyer-Berthaud, previously described from the localities of Kingswood and East Kirkton, whereas Rhacopteris shows similarities with the petiole attributed to Bilignea from Oxroad Bay. Both foliage types conform to seed-fern frond organisation. This new evidence contradicts previous interpretations of Rhacopteris as a fern or a progymnosperm. We suggest that Rhacopteris lindseaeformis and Spathulopteris obovata represent the foliage of some of the arborescent gymnosperms which are found associated in several contemporaneous localities.

Plants of gymnospermous affinities are the most important component of the flora at East Kirkton. Four genera of anatomically preserved gymnosperm stems with well developed secondary xylem are interpreted as arborescent. The largest specimens (trunks up to 50 cm in diameter) are attributed to the genus Pitus. Features of the wood, including ray size, are characteristic of the species Pitus withamii Lindley & Hutton which has long been described from the Strathclyde (former Oil-Shale) Group of Scotland. Decorticated axes of Eristophyton fasciculare are more common; their study has enlarged our concept of the species with regard to maximum diameter, internode length and phloem organisation. Similarly, the decorticated specimens of Bilignea solida Kidston found at East Kirkton exceed in diameter the original material described from Ayrshire. The fourth taxon is Stanwoodia recently described by Galtier and Scott (1991). In all these plants, features of leaf traces suggest that leaves were relatively large and densely borne on ultimate branches. These leaves were shed ultimately, prior to a later phase of wood development; they certainly correspond to (? most of) the compression foliage commonly found in association: Sphenopteridium, Adiantites and Spathulopteris.

A new taxon of probable early gymnosperms is described from permineralised specimens showing excellent preservation of the tissues, from the late Lower Carboniferous (Dinantian), Brigantian, deposits of the Midland Valley of Scotland. Stanwoodia gen. nov., represented by the single species S. kirktonensis sp. nov., shows the combination of a primitive protostelic organisation with a dense secondary wood. It closely compares to the enigmatic genus Bilignea which was formerly referred with some reservations to the Cordaitales. Another interest of the new plant concerns the excellent preservation of the phloem with at least three different types of constituent cells including fibres. Stanwoodia also exhibits the oldest well-documented evidence of a sequent periderm or rhytidome in fossil plants.

A review of current knowledge of the distribution of Palaeozoic ferns and fern-like plants is presented. Whilst numerous putative ferns occur in the Devonian, it is not until the Lower Carboniferous that ferns belonging to the Filicales appear. The Namurian represents a major gap in our knowledge. The ecology of late Palaeozoic ferns is reviewed. The association of early fern assemblages with volcanic terrains is considered particularly significant in the relationship between evolution and environment. Extinction of more specialised groups may have been caused by climatic changes.

A review of current knowledge of early fern evolution is presented including new data on age, morphology and anatomy with two diagrams summarising the early diversification of cauline and foliar anatomy and of the reproductive structures. The relationships and even the attribution of some Devonian taxa to the ferns is questioned whilst most of the Carboniferous coenopterids are considered indisputable ferns, some of them being related to modern filicaleans. The discovery, in the Lower Carboniferous of Scotland, of diverse annulate filicalean sporangia suggests an earlier (Tournaisian) radiation of true ferns than was previously assumed.

Twelve localities of Lower Carboniferous strata in Scotland (Loch Humphrey Burn, Glenarbuck, Pettycur, Oxroad Bay and the Berwickshire localities of Cove, Burnmouth, Gavinton, Edrom, Foulden) and in France (Esnost, Roannais, Montagne Noire) have been investigated with particular regard to their anatomically preserved floras. New data on the composition and preservation of the assemblages, their geological setting and stratigraphical age, using palynology in particular, are presented. Present data suggest that four successive groups of floras obtained from these localities can be recognised: from the Montagne Noire (mid to late Tournaisian), from the Berwickshire localities and Oxroad Bay (late Tournaisian to early Viséan), from Loch Humphrey Burn and possibly Glenarbuck (mid Viséan) and from Roannais, Esnost, and Pettycur (late Viséan). The similarities and differences between the floras are discussed with particular emphasis on stratigraphical as opposed to ecological controls. Comparisons are made with the New Albany Shale floras of the U.S.A., the Saalfeld and Glätzish-Falkenberg floras from the German Democratic Republic. The data suggest that the ferns and pteridosperms show the most striking changes through the Lower Carboniferous strata.