Two new species of Cyperus (Cyperaceae) from the Zambezian region of Africa

Cyperus absconditicoronatus Banters, Reynders & Goetgh. and C. unispicatus Banters, Reynders & Goetgh., two new species of Cyperus L. (Cyperaceae) from Angola and Zambia, are recognized. Cyperus absconditicoronatus is a tall species (55-100 cm) characterized by a scaled rhizome, a single terminal capitulum, a ciliated spikelet bract, and deciduous spikelets. Cyperus unispicatus can be recognized by a swollen and fibrous stem base growing from slender rhizomes, a single terminal spike, and short involucral bracts. The taxa are described and illustrated, and differences with the closest resembling species are discussed

Uncinia (Cyperaceae) of Ecuador

Nine species of Uncinia (Cyperaceae: Caricoideae) are recorded from Ecuador, one of which, U. ecuadorensis, is newly described and illustrated here. Descriptions, illustrations, distribution maps, and both artificial and vegetative keys are provided for the nine species, and for some uncinias additional taxonomic, phytogeographic and ecological comments are made. A lectotype is designated for the name U. lenuis

The Schoenus Spikelet: a Rhipidium? A Floral Ontogenetic Answer

The inflorescence unit of Schoenus nigricans and S. ferrugineus consists of a zigzag axis and distichously arranged bracts, each of which may or may not subtend a bisexual flower. Each flower seems to terminate a lateral axis. These features have led to a controversy about the nature of the inflorescence unit, particularly whether it is monopodial or sympodial. It was often seen as a pseudospikelet composed of a succession of lateral axes, each subtended by the prophyll of the previous axis, as in a rhipidium. Many authors, however, consider the inflorescence units of all Cyperaceae to be indeterminate, racemose, actual spikelets. In our study, we present new SEM observations on the floral ontogeny of S. nigricans, corroborating a monopodial interpretation of the spikelet. Concaulescent growth of the flower primordium and the spikelet apex explains: (1) the presence of a peduncle under the flower, (2) the advanced development of the subtending glume compared to its own flower primordium, and (3) the position of the distal glume with regard to the distal flower primordium

Species relationships in the genus Vasconcellea (Caricaceae) based on molecular and morphological evidence

Validity of the taxa currently recognized in the genus Vasconcellea was analyzed by investigating morphological and molecular data from 105 specimens of this genus and six specimens of the related genus Carica. Taxon identification of these specimens was compared with clustering in two phenetic dendrograms generated with 36 morphological characters and 254 amplified fragment length polymorphic (AFLP) markers. Moreover, cytoplasmic haplotypes were assessed using polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) of one mitochondrial and two chloroplast DNA regions. Results show that the morphological data set, containing mainly vegetative characteristics, merely reveals external resemblance between specimens, which is not directly associated with genetic relationships and taxon validity. Phenotypic plasticity and intercompatibility between several species are likely to confuse morphological delimitation of the taxa. Based on the results of our study, several specimens that could not be identified with the currently used identification key (1) could be attributed to a known taxon, which should be extended to include a higher range of morphological variability or (2) could be hypothesized to be of hybrid origin. Because of the high intraspecific variation within V. microcarpa and V. X heilbornii, revision of these taxa is recommended

Verhuellia is a segregate lineage in Piperaceae: more evidence from flower, fruit and pollen morphology, anatomy and development

Background and Aims The perianthless Piperales, i.e. Saururaceae and Piperaceae, have simple reduced flowers strikingly different from the other families of the order (e.g. Aristolochiaceae). Recent molecular phylogenies proved Verhuellia to be the first branch in Piperaceae, making it a promising object to study the detailed structure and development of the flowers. Based on recently collected material, the first detailed study since 1872 was conducted with respect to morphology, anatomy and development of the inflorescence, pollen ultrastructure and fruit anatomy. Methods Original Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Light Microscopy (LM) observations on Verhuellia lunaria were compared with Piperaceae, Saururaceae and fossils. Key results The inflorescence is an indeterminate spike with sessile flowers, each in the axil of a bract, developing in acropetal, helical succession. Flowers consist of two (occasionally three) stamens with basifixed tetrasporangiate anthers and latrorse dehiscence by a longitudinal slit. The gynoecium lacks a style but has three to four stigma branches and a single, basal orthotropous, and unitegmic ovule. The fruit is a drupe with large multicellular epidermal protuberances. The pollen is very small, inaperturate, and areolate with hemispherical microechinate exine elements. Conclusions Despite the superficial similarities with different genera of Piperaceae and Saururaceae, the segregate position of Verhuellia revealed by molecular phylogenetics is supported by morphological, developmental and anatomical data presented here. Unitegmic ovules and inaperturate pollen, which are synapomorphies for the genus Peperomia, are also present in Verhuellia

Molecular phylogenetic study of Scleria subgenus Hypoporum (Sclerieae, Cyperoideae, Cyperaceae) reveals several species new to science

Scleria subgen. Hypoporum (Cyperaceae), with 68 species, is the second largest subgenus in Scleria. Species of this pantropically distributed subgenus generally occur in seasonally or permanently wet grasslands or on shallow soils over sandstone or lateritic outcrops, less often they can be found in (open) woodlands. Previous studies established the monophyly of the subgenus, but the relationships between the species remained uncertain. In this study, DNA sequence data of 61 taxa of Scleria subgen. Hypoporum, where possible represented by multiple accessions from across their distributional range, were obtained for four molecular markers: the coding chloroplast marker ndhF, the chloroplast intron rps16 and the nuclear ribosomal regions ETS and ITS. Phylogenetic trees were constructed using Bayesian inference and maximum likelihood approaches. A species tree was constructed to summarise the results. The results indicate the existence of three sections: the monotypic, pantropically occurring, Scleria sect. Lithospermae, a new section from central and south America containing two species, and Scleria sect. Hypoporum, also pantropically distributed, containing the remainder of the species of the subgenus. Relationships in the latter section are not fully resolved. However, three or four different clades can be distinguished supported by some morphological characters. Our results indicate at least six new species in Scleria sect. Hypoporum. The new section and species are described in a taxonomical treatment. Their morphology is compared with (morphologically) closely related species

De \u27houten eeuw\u27 van een Vlaamse stad. Archeologisch en dendrochronologisch onderzoek in Ieper (prov. West-Vlaanderen)

European oak is the most suited species for dendrochronological research in Flanders. However, a local reference chronology, indispensable for the optimal implementation of dendrochronology as a dating tool, is not yet available. This is partly due to the assumption that in Flanders lowland oaks grow very fast and do not record a climatological signal in their growth-ring pattern. Furthermore, the strong pressure of humans on local forests is believed to have often disrupted the natural growth pattern of trees. As a consequence, little dendrochronological research has been carried out, making it impossible to develop a local reference chronology. This has resulted in poor dating success in the few cases in which analyses were attempted. This situation has led to the assumption that dendrochronology is not the most recommended dating technique for archaeological timbers and artefacts of local origin. In 1993, during an archaeological inspection of the Verdronken Weide outside the town walls of Ypres, numerous wooden timbers from a deserted medieval village were found. This find revived the demand for an intensive dendrochronological survey. This survey was first undertaken as part of a masters degree thesis (Dept. of Biology, Ghent University, in collaboration with the Laboratory of Wood Biology & Xylarium, Africamuseum, Tervuren) and was later continued by the Laboratory of Wood Technology (Ghent University). Over the years, wood from more archaeological sites in Ypres has been added to the database. This paper presents the results and historical interpretation of the dendrochronological research of wood from the Verdronken Weide and six other archaeological sites in Ypres