Notes on the genus Exostema (Rubiaceae), its limits and sectional subdivision

Based on recent molecular work by Paudyal & al., the generic limits of the Neotropical woody genus Exostema are reassessed with a view of making them more compatible with traditional, morphology-based generic concepts. A wide circumscription is favoured, congruent with Paudyal & al.'s “clade B” (the Exostema-Solenandra-Coutarea-Hintonia group). Thus defined, Exostema is a genus with 40 species and five natural sections and incorporates three generic splits that were proposed by Paudyal & al. To minimise nomenclatural disruption, a proposal to conserve the name Exostema Rich. against Coutarea Aubl. has been presented separately. Two new combinations at sectional rank are proposed

A new Australian species of Luffa (Cucurbitaceae) and typification of two Australian Cucumis names, all based on specimens collected by Ferdinand Mueller in 1856

As a result of his botanical explorations in northern Australia, Ferdinand von Mueller named several Cucurbitaceae that molecular data now show to be distinct, requiring their resurrection from unjustified synonymy. We here describe and illustrate Luffa saccata F. Muell. ex I.Telford, validating a manuscript name listed under L. graveolens Roxb. since 1859, and we lectotypify Cucumis picrocarpus F. Muell. and C. jucundus F. Muell. The lectotype of the name C. jucundus, a synonym of C. melo, is mounted on the same sheet as the lectotype of C. picrocarpus, which is the sister species of the cultivated C. melo as shown in a recent publication

an annotated, synonymic inventory, with links to the protologues and mention of original material

Background An inventory is presented of all names so far validly published in Cynoglossum sensu lato and its segregate genera: Adelocaryum, Afrotysonia, Kuschakewiczia, Lindelofia, Mattiastrum, Paracaryum, Rindera, Solenanthus, Trachelanthus, and their synonyms. Names and designations that were not validly published in the cited place, and later isonyms, are accounted for when they have been included in the International Plant Name Index (IPNI). Problems with IPNI entries, including errors and omissions, are discussed, and the hope is expressed that the present inventory may be of use for fixing them. New information The inventory, generated from a list of structured data, is presented in two Supplements, as a searchable HTML document comprising a sequence of entries with internal cross-links and links to external sources, in particular to protologues accessible online or, copyright restrictions permitting, made available as scanned documents via DOIs, and as machine- readible file. With minor exceptions, all names have been verified in their original place of publication, and all were nomenclaturally assessed. Colour coding is used to distinguish between names (in green) pertaining to Cynoglossum sensu lato, for which complete synonymies are provided; and names (in orange) pertaining to other genera but published under Cynoglossum or its segregates. They are listed together with their basionym and the corresponding correct name (if it exists), but without complete synonymy. Acceptable, potentially correct names appear in bold-face type, both under a broadly defined Cynoglossum (for which purpose validation of 81 new combinations and the name of 1 new species was necessary) and under one or more of its segregates. When a name was published for a new taxon, original material is indicated, usually by direct quotation from the protologue. New type designations are exceptional (two cases), whereas former type designations are cited whenever known. Furthermore, types and original specimens, especially when their digital images are available online, are mentioned with their locations and accession numbers. Comments are added whenever appropriate, especially to explain nomenclatural assessments that are not self-evident

Non-Linear I-V Characteristics of Double Schottky Barriers and Polycrystalline Semiconductors

An attempt to determine theoretically the highly non-linear current-voltage (I-V) characteristics of polycrystalline semiconductors, such as ZnO-based varistors, is made from the electrical properties of individual grain boundaries under dc bias. The role played by the fluctuations of double Schottky barrier heights at grain interfaces on driving electrical breakdown phenomena of macroscopic samples is pointed out in terms of a binary mixture model. An alternative trial form for the double Schottky barrier height is introduced to reproduce the breakdown voltage as well as the high non-linear coefficient alpha, where I propto V^{alpha}. ------------- Copies upon request to: [email protected]: CM-ICTP/92/1

Biological nomenclature terms for facilitating communication in the naming of organisms

A set of terms recommended for use in facilitating communication in biological nomenclature is presented as a table showing broadly equivalent terms used in the traditional Codes of nomenclature. These terms are intended to help those engaged in naming across organism groups, and are the result of the work of the International Committee on Bionomenclature, whose aim is to promote harmonisation and communication amongst those naming life on Earth

La flore de l'ile de Psara (Egée orientale, Grèce) : un catalogue commenté

Introductory chapters on the geography, vegetation and history of botanical ex loration are followed by a catalogue of 331 species of wild vascular plants, 90% of which represent first records for the island. Synonymy, references, localities and ecological data are given for each species in a condensed form. The taxonomy, nomenclature and distribution of some taxa are discussed; in one case (Silene cythnia) a drawing and a distribution map are supplied. Nomenclatural novelties are validated in the genera Centaurea, Matricana, Melica (by W. Hempel) and Trifolium. A phytogeographical and ecological analysis of the flora demonstrates its striking banality and the unexpectedly high proportion of anthropophytes. No pliytogeographical link with tlie other E. Aegean Isiands and Anatolia exists, but there are some affinities with the Cyclades. The observations are consistent with the hypotliesis of a long insular isolation leading to a strong depletion or even destruction of the original flora, which has been replaced by long-distance dispersed and anthropophytic elements

Origin and peculiarities of Mediterranean island floras

The countless small to minute islets of the Mediterranean Sea show a surprising floristic originality. They are ideal natural laboratories in which the biogeographer can study questions of long-range dispersal and migration, species turnover, and population dynamics. The larger islands have functioned as conservatories for mid-Tertiary floras to which they have provided shelter from the climatic fluctuations of the Pleistocene era and correlated shifts of vegetation belts. Their native flora was presumably impoverished after long-lasting insular isolation but that deficit has since been replenished by the activity of Man. Their rate of endemism is comparatively high. Vulnerability of island floras, as evidenced by documented cases of extinction, is prominent in the case of small, distant volcanic islets, but on the large islands virtually no loss of endemic species has so far occurred. The same is not true for the non-endemic element of the floras, however. In view of expanding tourism and shifting economy, measures for the conservation of island floras are necessary, but if designed intelligently and taken immediately they can still achieve saving virtually the whole floristic diversity at reasonable cost. It is important that they should include provision for encouraging and supporting research on threatened plants and their natural biota.Les innombrables petits îlots de la mer Méditerranée, même les plus minuscules, montrent une originalité floristique remarquable. Ils sont les laboratoires naturels rêvés du biogéographe, où il peut étudier les phénomènes de dissémination et migration à distance, de turnover d’espèces et de dynamique des populations. Les grandes îles ont servi de conservatoires aux anciennes flores du Tertiaire moyen qu’elles ont mises à l’abri des fluctuations climatiques du Pléistocène et des déplacements des ceintures de végétation associés. Leur flore indigène était probablement appauvrie suite à de longues périodes d’isolement insulaire, mais ce déficit fut ensuite comblé grâce aux activités humaines. Leur taux d’endémisme est relativement élevé. La vulnérabilité de ces flores, estimée sur la base des cas documentés d’extinction, est très grande dans le cas de quelques îlots volcaniques lointains, mais sur les grandes îles le nombre d’espèces endémiques disparues est pratiquement nul. Il n’en est pas de même cependant de l’élément non-endémique. En raison du tourisme toujours croissant et d’autres changements économiques des mesures pour la conservation des flores insulaires s’imposent, mais si elles sont conçues intelligemment et réalisées sans tarder nous pouvons encore espérer sauver la diversité floristique intégrale à un coût relativement modeste. Il est important, cependant, que de telles mesures englobent l’encouragement et le soutien de recherches sur les plantes menacées et leur milieu naturel.Greuter Werner. Origin and peculiarities of Mediterranean island floras. In: Ecologia mediterranea, tome 21 n°1-2, 1995. Connaissance et conservation de la flore des îles de la Méditerrannée. Ajaccio, Corse, France (5-8 octobre 1993) pp. 1-10