Belgian Journal of Botany

Publications
In terms of phytosociology Nuphar lutea and Nymphaea alba are species characteristic of the same nymphaeid association. In many lakes, however, they develop separate communities. Habitat differences between patches of both species may thus be expected. The aim of this study was to find out if neighbouring patches of Nuphar lutea and Nymphaea alba were characterised by different water and substratum properties. Field investigations ware carried out in a shallow lake with well-developed macrophytic vegetation (Lake Jarosławieckie, Wielkopolski National Park, mid-Western Poland). An additional sampling site was located in the macrophyte-free mid-lake. Water and substratum samples were collected twelve times during a two-year study. Considering the whole data set, the water properties did not differentiate significantly the studied phytocoenoses and the open water. Temporal differences appeared to be more significant. In the case of substratum properties, habitat differentiation was found for organic matter content, which was significantly higher at the Nymphaea alba site, whereas total nitrogen content was higher at the mid-lake site. Seasonal dynamics of the habitats followed a similar pattern for the water properties, whereas differences in organic matter content were found for the substratum properties.
 
The causes of early embryo abortion in reciprocal crosses between Phaseolus vulgaris L. and Phaseolus polyanthus Greenm. were studied. Methacrylate resin sections, 2 m thick, of 2 to 6 day-old hybrid seeds were used to examine the stages of embryo development and the state of seed tissues. These observations permitted to suggest the main causes of abortion and to identify the developmental stages at which hybrid embryos should be rescued. Early nutritional barriers in P. polyanthus () × P. vulgaris crosses are related to a deficient endosperm development while in reciprocal crosses, endothelium proliferation and to some extent, hypertrophy of the vascular elements might be the main causes of early embryo abortion. The importance of the abnormalities observed during embryo development depended to a great extent on the compatibility between the genotypes crossed. Our results also suggest that the appropriate time for embryo rescue when P. polyanthus is a female partner is at the early globular stage. Several parameters of in vitro culture were analysed within the two parental species : genotype, culture medium, age of the collected pods. The results show that plantlets regeneration can be obtained satisfactorily in P. vulgaris, while the rate of success remains limited in P. polyanthus.
 
This study tests the hypothesis that silica accumulation in grasses is an inducible response to grazing. It also examines if silica concentration is correlated to other leaf structural and chemical parameters. To that end, five tropical grass species (Andropogon gayanus var. bisquamulatus, Elymandra androphila, Hyparrhenia subplumosa, Panicum maximum var. C1 and Panicum maximum var. local) were subjected to various clipping treatments in cultivation. Clipping was found to increase silica concentration in three of five species (blades and sheaths), but this response was rarely strong and varied with clipping frequency. Defoliation also caused other changes in leaf structure, i.e. production of leaves with juvenile characters including higher Specific Leaf Area (SLA), higher Relative Water Content (RWC), and lower carbon concentration. This suggests that enhanced silica accumulation is not a very specific response to defoliation. Silica concentration also varied among species and was correlated to leaf structure and chemical composition. Andropogon gayanus var. bisquamulatus had the lowest silica concentration and the highest carbon concentration, while Panicum maximum showed the opposite combination of traits, suggesting that species with more sclerified leaves might be less silicified. Positive correlations between silica content and RWC, soluble ash, and SLA suggest that variation in silica accumulation among species and treatments might be related to transpiration rate.
 
? Relative growth rate (RFWG; in %) of calli obtained from two sugarcane cultivars (CP65-357, salt-sensi tive and NCo310, salt-resistant) and exposed during 1 month to different concentrations of NaCl. Vertical bars represent S.E.  
K+/Na+ ratio of sugarcane calli obtained from two cultivars ( CP 65-3 57, salt-sensitiv e and
The effects of salt on growth, ion and proline accumulation were investigated in vitro in two sugarcane cultivars : NCo310 (salt-resistant) and CP65-357 (salt-sensitive). Leaf explant-derived calli obtained from the two sugarcane (Saccharum sp.) cultivars were exposed to four concentrations of NaCl (0, 34, 68 and 102 mM). Relative growth rate, ion concentrations and proline accumulation were quantified after 4 weeks of stress. NaCl inhibited growth in the two cultivars but to a lower extent in calli issued from NCo310 comparatively to calli obtained from CP65-357. In response to salinity, Na+, Cl− and proline concentrations increased significantly in calli of both cultivars while K+ concentration decreased. The two cultivars accumulated similar quantities of Na+; the highest accumulation of Cl− occurred in calli of salt-tolerant NCo310 coupled with the lowest decrease in K+ concentration. Calli issued from CP65-357 accumulated more proline than those of NCo310. These results suggested an implication of Cl− and K+ in salt resistance at cellular level in these genotypes and that proline is a symptom of injury in stressed sugarcane calli rather than an indicator of resistance.
 
Haplotype network in Zannichellia. Each branch represents one mutation and open circles missing haplotypes. Character state changes (with position) are given. Haplotype C contains a duplication.
Neighbor-joining tree of Zannichellia populations from Europe based on ccmp3 haplotypes.
Distribution of Zannichellia chloroplast haplotypes in Europe.
The successful amplification of consensus chloroplast microsatellite markers (cpSSRs) from 22-year-old dried fruits of Zannichellia, originally sampled as a reference herbarium collection for an isozyme study, is reported. The DNA obtained from herbarium tissues was not degraded and revealed amplicons of the same length in old achenes and leaves than in fresh materials of both tissues from the same site. DNA extraction was also performed on single achenes of about 1 mg dry weight. Out of the ten cpSSRs tested, four gave reliable PCR products in both fresh and dried plant materials. Three polymorphic cpSSR loci allowed to distinguish five haplotypes, A, B, C, D, and E from the ancient DNA. Haplotype A is widespread in Z. palustris subsp. palustris and subsp. repens from West-European inland fresh water localities and in Z. major from the brackish waters of the Baltic Sea. Haplotype B is found in Z. palustris from the Baltic Sea, whereas haplotype C seems to be confined to Z. pedunculata, a taxon from northwestern Europe. Haplotypes D and E were observed in Z. palustris and Z. peltata, respectively, from the Mediterranean region. A haplotype network and neighbor-joining tree revealed the possibility of a cryptic species within Z. palustris. The chloroplast microsatellite primers show a potential in detecting haplotypes of Zannichellia, especially at taxon level, as well as in detecting geographical patterns across distant European fresh and brackish water habitats.
 
This study was carried out in the Sudanian (9°45'–12° N), Sudano-Guinean (7°30'–9°45' N) and Guinean (6°25' – 7°30' N) zones of Benin. The distribution and relative abundance of the baobab was studied by means of megatransects and by surveying a number of selected sites. In each zone, an estimate was made of pulp, seed and kernel production from 1200 fruits harvested from 30 individuals. In the Sudanian zone and in some regions of the Dahomey-Gap in the Guinean zone, a population density of 5 baobabs per km2 was recorded. In the Guinean zone, a density of only 1 baobab per km2 was recorded. The baobab population's occurred on sandy soils in the Sudanian and Guinean zones and on sandy–clayey soils in the Sudano-Guinean zone. Flowering and fruiting of the baobab is seasonal. The morphology and productivity of individual baobabs varied significantly from one zone to another. The zones with high values of potential evaporation, rainfall, relative humidity, temperature, pHwater and percentage of fine silt are associated with a low seed and fruit pulp production. The higher the pHKCl, the percentage of total nitrogen, organic carbon and organic matter, the higher the number of seeds produced by an individual baobab. The higher the clay and crude silt content of the soil, the better the productivity.
 
ISSR markers were used to assess the spatial genetic structure and isolation by distance in Salix alba populations along an altitude gradient in two contrasting rivers on a southern and a northern slope in the Alps. Five populations along the Alto Adige-Adige and four populations along the Upper Rhine-Rhine were investigated for ISSR polymorphism. A PCoA showed that most individual trees of the river Adige and of the river Rhine group together as a single species. The number of polymorphic loci, the proportion of polymorphic loci and Nei's gene diversity were higher for the Adige than for the Rhine. FST/(1 − FST) ratios between populations increased significantly with geographic distance for the Adige. This increase was also present for the Rhine but it was not significant. The relationship between pairwise FST/(1 - FST) and interpopulation altitude differences was not significant for both rivers. The within-population spatial genetic structure of both rivers showed positive values of the pairwise relationship coefficient in the first distance classes (0 - 25 m), which is an indication of isolation by distance within populations of both river transects. The Sp-statistic revealed a rather strong spatial genetic structure in both river basins. A pattern of genetic structure that corresponds to the model of isolation by distance was thus found at both intra and interpopulation levels. ISSR markers proved to be useful in estimating isolation by distance and spatial genetic structuring at both population and individual level for S. alba populations.
 
Life cycle of Diplochytridium sexuale Karling, a parasitic chytrid infecting cells of the filamentous Xanthophyte Tribonema vulgare Pascher observed in a small eutrophicated, clear water pond (Maten 13, Genk, Belgium) in November 1998. A. Encysted zoospore with a large, refractive lipoidal globule. B. Sporangium development. Growth takes places only at the apex of the zoospore cyst leaving behind a basal, thick-walled appendage. C-D. The rhizoidal system (a more or less globular apophysis without rhizoids) inside the host cells, visualised by epi-fluorescence microscopy after staining with Calcofluor White (MÜLLER & SENGBUSCH 1983). The apophysis is already completely developed before sporangium growth takes place. E. Mature clavate zoosporangium with many lipoidal bodies. F. Empty sporangium with a large, apical exit pore. Also visible are the germ tube (arrow) and the apophysis inside the host cell. G. Fusion of a 'female' encysted zoospore and a 'male' zoospore to eventually form a resting spore. H. Unknown structure, which could be interpreted as a resting spore. Scale bar = 10 µm.
Site map of the Schelde estuary, with indication of the sampling location (black dot) in the freshwater tidal reaches of the Schelde river.
Fluctuation in biomass (µg C/l) of the dominant phytoplankton taxa and total phytoplankton density (cells/ml) in the upper reaches of the Schelde estuary in the summer 1996.
Fluctuation in biomass (µg C/l) of the Scenedesmus population at the sampling location and the infection prevalence of Rhizophydium scenedesmi (Fott) Karling as expressed in % of total Scenedesmus coenobia. Coenobia on which the fungus had completed its lifecycle (empty sporangia) were not included in this parameter.
Different protists, capable of affecting phytoplankton populations in the upper reaches of the Schelde estuary. A-H. Podochytrium-like chytrids, infecting the centric diatom Cyclotella scaldensis. Four different morphotypes were observed, all had a more or less clearly visible basal cell (long arrow), but they differed in the amount and location of the dehiscence pores (small arrows). I. Mature sporangium of an unknown chytrid on Cyclotella atomus. J-M. The chytrid Podochytrium cornutum, infecting cells of Actinocyclus normanii. These chytrids have a narrow but large sporangium and a clearly visible basal cell with an inclination just above (arrow). The exit pore is situated at the apex and sometimes the lid is still attached (arrowhead). The rhizoidal system consists of branched mycelium. N-O. Mature and empty sporangium of Rhizophydium scenedesmi (Fott) Karling, infecting a Scenedesmus coenobium. P. Sporangium of Entophlyctis apiculata, a parasitic biflagellate fungus inside a Pteromonas cel. Q-T. Digestion cyst from the herbivore amoeba Asterocaelum algophilum with and without amoebae. The food contents of its prey (centric diatoms) can be easily distinguished.
In the summer of 1996, a detailed survey of natural phytoplankton samples from the freshwater part of the Schelde estuary was carried out to check for the occurrence of poorly studied heterotrophic protists, the herbivorous amoeba Asterocaelum algophilum and chytrid parasites. The plankton community during the summer bloom was dominated by centric diatoms (Cyclotella scaldensis, C. atomus). Fungal infestations of these bloom-forming species were not observed in fixed samples, although severe infections were frequently observed in net samples which were maintained in the laboratory for a few days. The chytrid infecting the diatom Actinocyclus normanii was identified as Podochytrium cornutum. Four morphologically distinct chytrids resembling the genus Podochytrium parasitized cells of C. scaldensis. In contrast to the populations of centric diatoms, infection of the riverine Scenedesmus population by the chytrid Rhizophydium scenedesmi occurred in situ. The infection prevalence was maximum ca. 24%, leading to a twofold reduction in the biomass of Scenedesmus. It is hypothesized that the condition of the host population is a discriminating factor since only the allochtonous phytoplankton populations get infected, when entering the estuary. On the other hand, Asterocaelum algophilum was shown to feed voraciously on centric diatom cells. Cyclotella atomus, C. scaldensis and Stephanodiscus hantzschii were its main prey; infrequently, some green algae (Crucigenia) were found ingested too. At times, the amoeba was capable of grazing away ca. 25% of the diatoms per day. On average, larger diatom cells were found relatively more frequently inside 'feeding cysts' of this unusual amoeba when compared to the undigested centric diatom populations, which suggests the occurrence of some size-selectivity in the feeding behaviour of A. algophilum. Since sometimes more than 70% of the C. scaldensis cells and more than 50% of the S. hantzschii cells were found ingested, the impact of grazing by A. algophilum on the populations of the larger diatom species in the estuary can be significant. As a result, more attention should be paid to the presence and role of these organisms in aquatic food web studies.
 
Glutathione is an important antioxidant that plays key roles in plants through the activation of defense genes and redox buffering of the cells, by sensing reactive oxygen species (ROS) and by participating in ROS-signaling pathways that control the fate of plants. In the present study we investigated intracellular differences in contents of glutathione and of one of its precursors, cysteine, in leaves of sugar beet (Beta vulgaris L.) in response to black bean aphid (Aphis fabae) infestation, within mesophyll cells as close as possible to the stylet penetration site (< 0.05 mm) and within cells further away from the stylet penetration site (> 1 cm). When compared to cells from uninfested plants glutathione content was much higher in all cell compartments (by up to 156% in nuclei) at the stylet penetration site. Glutathione content was also higher (by up to 66% in nuclei) in cells further away from the stylet penetration site, where the induction of oxidative stress by the penetration and feeding process seems to be unlikely. These results indicate that glutathione could be involved both in the direct protection against oxidative stress possibly induced by the penetration of the stylet through the tissue or by the injection of saliva, and in signaling processes that might be related to the activation of defense genes. Cysteine, the rate-limiting factor for glutathione synthesis, was higher in most cell compartments close to the stylet penetration site (by up to 37% in nuclei) and much lower in cells further away from the stylet penetration site (by up to 54% in nuclei) indicating possible important roles of cysteine for glutathione synthesis at the stylet penetration site. Possible implications of our results in relation to glutathione synthesis are discussed.
 
The ecology and distribution of Poaceae species found on 12 inselbergs embedded in savannah and woodland (Benin) and on 25 inselbergs enclosed in rain forest (CEG: Cameroon, Equatorial Guinea and Gabon) are described. A total of 77 species were observed, 46 in Benin and 36 in CEG. Five species were strictly saxicolous in Benin and three in CEG, but most species (83%) were also present in the vegetation surrounding the inselbergs (the matrix). In Benin, 46% of the species were present on half of the inselbergs, while only one species did so in CEG. This unequal distribution of the species amongst sites in CEG could originate from dispersal limitation due to the strong ecological contrast between the inselberg biotope and the rain forest. Ecological conditions on the inselbergs are more similar to that of a savannah and woodland matrix, which could explain the homogeneity of inselberg vegetation in Benin. In CEG, four species were mainly distributed outside the lowland rain forest region: two in savannah and woodland, and two in mountainous vegetation. The discontinuous distribution of these species with inselberg satellite populations in the lowland rainforest is probably related to Quaternary vegetation changes. Inselberg in both study area contribute significantly to the regional species diversity by the presence of strictly saxicolous species or of species from other phytochoria. The inselberg habitat should therefore be considered in conservation policies.
 
, column 6)
Typical aspect of the Eragrostietum pilosae. The dominant grass species on the picture is Echinochloa colona. Total cover 100%, height 60 cm. Kissi, Oudalan (Burkina Faso), August 2001 (JM).  
First and second axis of the DCA of 108 phy tosociological relev?s from inundated grasslands in West Africa. Symbols represent five plant communi ties: ? Panicetum laeti, Eragrostietum pilosae, Dicliptero verticillatae-Echinochloetum colonae, O Tephrosio pedicellatae-Echinochloetum colonae, A Crinetum zeylanici.
A detailed phytosociological analysis of seasonally inundated grasslands with Echinochloa colona in semi-arid and sub-humid tropical West Africa is presented. Such grasslands are flooded during the rainy season and dry up during the rest of the year. E. colona is a thermo-cosmopolitan, annual and hydrophilous grass species. In West Africa, it is widely distributed and highly appreciated as a fodder plant for livestock. Our study area comprised subareas in Burkina Faso, Niger and Mali, covering two bioclimatic zones. The floristic structure of the vegetation was documented with 114 relevés, which were classified manually, and with a cluster analysis. Additionally, they were ordinated to characterize main floristic gradients. We describe a new alliance, the Panico laeti-Echinochloion colonae. It consists of five new associations (Panicetum laeti, Eragrostietum pilosae, Dicliptero verticillatae-Echinochloetum colonae, Tephrosio pedicellatae-Echinochloetum colonae, and Crinetum zeylanici). These plant communities show high cover values and colonize sandy, sandy-loamy or loamy to clayey soils that can be water-saturated or repeatedly inundated only during the rainy season. Soil type and topographical situation with duration of flooding were the most important differentiating factors, whereas precipitation was a secondary one. The predominant life-form was annual grasses. The results of the manual classification are largely congruent with the results of the multivariate techniques. In some cases, the floristic turnover between the plant communities has a continuum character. In particular, stands of Panicetum laeti are often intermixed with other associations. Four communities are documented for Burkina Faso, two for Niger and only one for Mali. Larger distribution areas of the newly described syntaxa beyond the study area can be assumed. Echinochloa colona is documented in other plant communities in various regions of tropical West and Central Africa, and colonizes not only inundated grasslands but also water meadows.
 
La recherche a porté sur les propriétés physique et chimique et la composition algale de 13 sources thermales situées au Burundi, en Afrique centrale, entre les altitudes 773 et 2550 m. Les eaux de ces sources sont principalement de type bicarbonaté, certaines sources étant très riches en chlorures ; leur température varie de 29°C à 57.5°C. Au total, 92 taxons appartenant aux groupes des Cyanobacteria, Chlorophyta et Bacillariophyta ont été observés dans 13 échantillons, 80 taxons appartenant à ce dernier groupe. Les espèces des sources thermales ne diffèrent pas de celles des autres eaux du Burundi déjà étudiées et peuvent être considérées comme des espèces thermo-tolérantes. Une analyse canonique des correspondances appliquée aux espèces de diatomées ainsi qu'aux variables physiques et chimiques a permis de repérer les taxons associés aux sources thermales faiblement minéralisées et ceux associés aux sources fortement minéralisées et indique que leur séparation est principalement due à la conductivité, aux bicarbonates et aux chlorures.
 
In this paper, we analyse the relationship between meteorology and Castanea airborne pollen. Chestnut is a tree broadly represented in the north of Spain. In view of its abundant pollen production and the high dispersal capacity of its pollen grains, atmospheric levels of Castanea airborne pollen (daily and hourly) in two localities in northwest Spain (Santiago de Compostela and Ourense) were studied from 1993 to 2001. The obtained results indicate the onset of flowering in the second fortnight in June, with the flowering maximum in July. Temperature was used as a predictive variable for predicting the onset of the pollen season and pollen concentrations. The forecast capacity of the sum temperature method in order to predict the onset of the pollen season was good, with a difference of 2-5 days between the real and the predicted onset dates in the year 2002. The time series regression lines well fitted the observed values during the year 2002. The proposed models are especially suitable for evaluating short-term effects of time-varying pollen appearance in the atmosphere. The obtained models of the hourly distribution did not reflect the hourly rhythm of pollen dispersion but rather the rhythm of pollen capture from the trees located at different distances and in different directions from the pollen trap.
 
A classical example of petal-to-stamen transition is the flower of white water lily (Nymphaea alba s.l., Nymphaeaceae). The description in terms of classical plant morphology cannot reveal all morphological variation of transitional organs. Our aim was to describe transitional structures of Nymphaea flower using an integrated approach, which could adequately reflect the nature of transitional structures. We collected 25 water lily flowers from four regions of European Russia. All the organs of the flowers were measured (2479 organs in total). Our data were analysed graphically and by various methods of multivariate statistics. To reduce the influence of size we computed two integrated "hybrid" morphological indices. The Euclidean distances from "typical stamen" and membership coefficients of fuzzy clustering were also calculated. In addition, we tested the descriptive ability of landmark-based geometric morphometrics.Besides traditional petal-to-stamen transition in Nymphaea flowers, we documented intermediate organs between sepals and petals, which were close to sepals by their morphology. Traditionally gradual petal-to-stamen shifts were postulated for Nymphaea flower. In spite of this postulate, our application of computing Euclidean distances method, of "hybrid" indices and of cluster membership of fuzzy clustering revealed that petals, stamens and transitional structures could be efficiently separated by their characters. The analysis of these characters shows diversity in morphology of flowers, collected from distinct regions of European Russia, which could be of taxonomic importance. It is remarkable that different morphological feature shifts, leading to substitution of sepals by petals and of petals by stamens, occur asynchronously.Flowers were investigated as "populations", where any separate organ represents a single "individual". Thus methods, used in plant population biology, may be applied to flower organs. Morphological nature of these organs is better revealed via integral characteristics such as "hybrid" indices, distances and cluster membership.
 
Persian leek (Allium sp.) is a cultivated food species, native to the Middle East, which is important economically but its taxonomic identity and relationship to other relative species remain unclear. Vegetative and floral morphology of different specimens of the Persian leek was studied in order to define its taxonomical position. The results support a close relationship to A. ampeloprasum L. derivatives. Mitotic studies of meristematic root cells in Persian leek specimens, showed the chromosome number to be consistently 2n = 4x = 32. However, the specimens differed in chromosome morphology and their karyograms were classified into two groups. Because of doubts regarding taxonomic identity of Persian leek with its nearest wild form, A. iranicum (Wendelbo) Wendelbo, a morphological comparison was made with respect to presence and shape of bulblets exterior to the main bulb, structure of the stamens, etc. and confirmed the Persian leek as a separate entity. There was no evidence for its presence in the wild and may thus be considered as a cultigen. Our analysis suggests that the Persian leek is a distinct subordinate group of A. ampeloprasum.
 
(a) Overview of the Bourgoyen-Ossemeersen. (b) Two sites were distinguished along the topographical transect in the nature reserve Bourgoyen-Ossemeersen, each consisting of a left, middle and right sampling point (×). Measurement devices are installed along the transect (their field positions and depths are given in Table 1) and connected to three data loggers (black boxes).
Field positions and depths [cm below surface] of monitoring devices.
In this paper, results from an intensive two-year monitoring campaign of a wetland gradient are presented and analyzed. Two spatially adjacent sites along a wetland gradient are described by means of abiotic variables, groundwater level, and soil temperature and soil moisture at several depths throughout the vertical soil profile. The vegetation of the sites is described on the basis of a species cover inventory, and two different vegetation types are distinguished along the wetland gradient: Arrhenatheretum elatioris at the highest end of the gradient and Caricetum gracilis at the lowest end. Aboveground biomass and leaf area index of both Arrhenatheretum elatioris and Caricetum gracilis were measured on a monthly basis, and their seasonal variation could be related to specific site conditions. Furthermore, evidence was found that vegetation was not passive to the environmental site conditions but actively influenced them. The groundwater at the lower Caricetum gracilis site showed diurnal fluctuations with amplitudes up to 10 cm, which could be attributed to transpiration losses by phreatophytes.
 
Restoration of floodplain forests has become a primary aim of sustainable forestry in Europe. Although several studies have investigated the conversion of coniferous stands outside of their biogeographical area and on unsuitable sites, none focused specifically on alluvial areas. We surveyed 208 riverine stands, distributed homogeneously throughout the Grand-duché de Luxembourg (western-central Europe) for the abundance of woody forest species (trees, saplings, seedlings and shrubs). The influence of both the canopy nature (Norway spruce or deciduous) and the biogeographical region (Oesling or Gutland) on the understorey regeneration were tested. The mean species richness was 10.5 woody plants per stand. Correspondence analyses showed that canopy tree regeneration was not different between the two forest types. Following an analysis of variance, we found that functional species group distribution (regarding mode of dispersal, type of seed bank and establishment strategy) was more determined by the biogeographical variable than by the canopy variable. Most woody species were significantly more abundant in deciduous forests and in the Gutland area. Only Rubus idaeus, Sambucus racemosa and Sorbus aucuparia were strongly associated with Norway spruce stands or the Oesling region. The differences between deciduous forests and coniferous stands are mainly due to shrub abundance and not to the canopy tree regeneration. In conclusion, Norway spruce plantations act as nurseries for late-successional riverine species like Fraxinus excelsior, Acer pseudoplatanus and Quercus robur.
 
? Feulgen stained karyotype (2n = 2x = 16) (a) and C-banding metaphase plate (b) of Alstroemeria gram?nea (GA91215). The scale bar represents 10 urn.
Characteristics of chromosomes 0/Alstroemeria gram?nea (GA91215; 2n = 2x = 16) based on measurements of 10 metaphase plates
Alstroemeria graminea Phil. (Taltalia graminea according to BAYER 1998) is the only annual species described within the genus Alstroemeria L. and its cytogenetic relationship with the perennial species have not been described. In this work, an analysis of the karyotype and the C-banding pattern of Alstroemeria graminea are reported. A. graminea, with an asymmetric karyotype 2n = 2x = 16, shows similar chromosome morphology with respect to the perennial Alstroemeria species previously analysed. However, some differences in relative length and position of the C-bands were observed in A. graminea. These differences were the presence of a centromeric band and an interstitial band in the short arm of pair 1 and pericentromeric bands in the long arms of pairs 3 and 7, which have not been observed in the other species. The cytogenetic data of the present study on A. graminea are concurrent with other species within the genus Alstroemeria, and do not justify the separation of this species from the genus Alstroemeria and its inclusion in the new monotypic genus Taltalia.
 
The monotypic genus Leontochir Phil. (Alstroemeriaceae Dumortier), represented by Leontochir ovallei, is endemic to Chile, and its geographical distribution is restricted to the coastal zone of the Atacama Desert (28°S). In previous cytogenetic studies on L. ovallei a diploid karyotype 2n = 2x = 18 was described. In this work a first analysis of the C-banding pattern of L. ovallei is presented. L. ovallei showed large regions of constitutive heterochromatin within the karyotype, with C-bands on all chromosome pairs except 9. The relative length of the C-bands was 20.0% of the total haploid set length. The presence of large regions of constitutive heterochromatin on the chromosomes was concurrent with the presence of many conspicuous and large chromocenters in the interphase nuclei. According to these results, L. ovallei shows the largest value of relative C-band length so far described within the Alstroemeriaceae. These cytogenetic results on L. ovallei increase the available data on C-banding patterns in Alstroemeriaceae with an additional genus.
 
Sugarcane, Saccharum officinarum L., is a C4 plant whose leaves show a typical Kranz anatomy which is often altered by pathogens. Leaf scald is produced by Xanthomonas albilineans, a yellow-pigmented, Gram-negative, and plant pathogenic bacterium member of Pseudomonaceae. This microorganism produces a xanthan-like polysaccharide which occludes both xylem and phloem, resulting in the desiccation of leaves. Some stomata of scalded leaves from cv. C973 73 appeared occluded by plugging material and trichomes seemed to be empty. The action of the pathogen seemed to be confined to the vascular bundles, particularly the large xylem vessels, which were often occluded with a plugging material. Stomata of yellow leaf syndrome (YLS)-diseased leaves were surrounded by a dense population of crystalline material. Bundle sheath cells surrounding both xylem and phloem elements were separated from the conducting tissues by a large layer of a wax-like substance. Sugarcane smut is caused by the dimorphic basidiomycete Ustilago scitaminea. Some fungal hyphae appeared on the abaxial epidermis of smut-infected leaves from cv. Barbados. Hyphae really penetrated through open stomata. Many parenchymatous cells were invaded by smut and their cell walls were broken by actively progressing hyphae. The production of mucilage was evident in parallel to a complete destruction of parenchymatous cells by fungal hyphae whereas many spores occurred inside the parenchymatous cells.
 
PCA of the complete disjunctive table of presence/absence of alleles at eight microsatellite loci for a sample of diploid and tetraploid Salicornia from the Atlantic coast in northern France and the Mediterranean coast in Corsica. PCA1 (horizontal axis) and PCA2 (vertical axis) account for 30.3% and 12.1% of the total allelic variance, respectively. Values of the highest correlation coef fi cients between the axes and the alleles are given at the extremity of each axis. 
Primer sequences and characterization of eight nuclear microsatellite loci in Salicornia for a sample of both diploid and tetraploid specimens from Mediterranean and Atlantic populations.
Eight nuclear microsatellite loci were identified using the method of microsatellite-enriched libraries in the glasswort genus Salicornia. These markers yield specific alleles for discriminating diploid and tetraploid lineages and thus provide a reliable and efficient tool for routine determination of ploidy level in the genus. Within both the diploid and tetraploid lineages, the microsatellites further display a clear biogeographic signal. A significant partitioning of genetic differentiation was found between the diploid populations (Fst = 0.31; p < 0.001). The new microsatellite markers described here thus offer the appropriate amount of variation to address issues of species delimitation and biogeographic history in the genus.
 
Picea omorika (Panč.) Purk. is a relict and an endemic species found exclusively in the Balkan, within an area of ca. 10 000 km2. Marker-based genetic diversity data in this conifer are very limited and partially contradictory. Therefore, twelve nuclear markers (ten EST-SSRs and two genomic SSRs) were tested for cross-species amplification in P. omorika. Five EST-SSRs amplified successfully and a very high number of alleles per locus was found in 50 trees originating from two natural populations (7 to 18 alleles per locus), with a total of 61 alleles. Furthermore, a high number of private alleles were detected - 13 and 14 per population, respectively. Rare alleles, i.e., alleles whose frequency was lower than 0.05, were not observed. Markers were selectively neutral, no linkage disequilibrium was detected and the genotype frequencies fitted Hardy-Weinberg proportions. Expected heterozygosity per locus ranged from 0.64 to 0.91 in both populations, with an overall mean of 0.83. Considering the small remnant population sizes of P. omorika, these values are unexpectedly high and comparable to values in P. glauca (Moench) Voss., P. sitchensis (Bong.) Carr. and P. mariana (Mill.) B.S.P. detected with an identical set of markers in samples of similar sizes.
 
Senecio salsuginea, A -Habitus, B -Capitulum, C -Achene
Centaurea tuzgoluense, A -Habitus, B -Capitulum, C -Outer phyllary, D -Inner phyllary, E -Achene
Diagnostic characters of Saponaria karapinarensis, S. mesogitana and S. kotschyi.
Diagnostic characters of Senecio salsuginea, S. pseudo-orientalis and S. doriiformis subsp. orientalis.
Diagnostic characters of Centaurea tuzgoluensis and C. zeybekii.
Three new species are described and illustrated from around Tuz Gölü from Central Anatolia (Turkey): Saponaria karapinarensis Vural & N. Adıgüzel (Caryophyllaceae), Senecio salsuginea H. Duman & Vural and Centaurea tuzgoluensis Aytaç & H. Duman (both Asteraceae).
 
Position of the Tiense Groef (discontinuous line), with transects within the present (bold line) and ancient forest boundaries (full line). The central cross represents two main roads crossing the forest.
Results of the Species Indicator Analysis on the raw vegetation (cover in percentage) and seed bank (number of seeds per m 2 ) abundance data.
On a landscape level, former land use is a structuring element of plant communities of recent and ancient forest patches. However, ancient land use has been recently identified to affect plant communities within ancient forests. An ancient holloway, i.e., a U-shaped sunken road, embedded in the Meerdaal forest was used to establish whether microtopographical changes brought about by the former road use would structure the forest vegetation and seed bank. Seven transects were set out perpendicular to the holloway over a one kilometer stretch, to test whether the sunken road would locally shape the patterns in abiotic conditions, vegetation and seed bank. Soil pH was significantly higher within the holloway, which was reflected in a higher plant cover, ancient forest and overall species richness. Vegetation composition was altered by the road microtopography, though secondary to a prevailing fertility gradient with distance along the holloway. While seed bank characteristics did not differ between road and non-road plots, seed bank composition did vary according to the microtopography. However, the extant vegetation caused the observed seed bank pattern. The holloway shapes understory community patterns in vegetation and seed bank. As the sunken road cuts into deeper calcareous soil layers at the bottom of the road, this gave way to differential acidification (different buffer ranges) in function of the microtopography, allowing the persistence of favorable growth conditions within the holloway. Hence, these conditions allow the survival of ancient forest species within the road in a forest matrix made increasingly unsuitable through severe acidification.
 
Genetic diversity of ulluco (Ullucus tuberosus), maintained ex situ and originating from Peru and North Bolivia, has been analysed using morphological traits and inter-simple sequence repeat (ISSR) markers, along with passport data. With regard to morphological and ISSR variation, our study revealed a high number of morphotypes and genotypes. Morphological and molecular results were congruent and both correlated with geographical distribution. Moreover, comparison of molecular and morphological characterisation of accessions indicated the existence of intra-morphotype heterogeneity. We discuss the genetic structure of ulluco in relation to characteristics of the species and of the Andean agricultural system. Patterns of diversity probably have a geographical origin and have been modified for centuries by Andean farmers, at small and large scales. The fact that both morphological and molecular markers correlate with geographic distribution is of high interest for genetic diversity studies and for genetic resource conservation of Andean tubers and of other vegetatively propagated crop species.
 
A checklist of the Mimosoideae (Leguminosae) of Equatorial Guinea comprising 21 genera and 40 taxa is presented. Two species are known from Annobón, 18 from Bioko and 37 from Río Muni. The best represented genera are Albizia and Newtonia with five species each. In addition, bibliographic references for Mimosoideae (Leguminosae) from Equatorial Guinea have been gathered and checked. Fourteen taxa are recorded for the first time from the country. A statistical summary is presented at the end of the checklist.
 
A checklist of the Cyperaceae of Equatorial Guinea, comprising 95 species, is presented. Thirteen species are known from Annobón, 45 from Bioko and 73 from Río Muni. The best represented genus is Cyperus, with 25 species. In addition, bibliographic references for Cyperaceae from Equatorial Guinea have been gathered and checked. Twenty-two species are recorded for the first time from the country.
 
Loja Province (southern Ecuador) is generally acknowledged to be located in the centre of origin of cherimoya (Annona cherimola Mill.), a promising Andean fruit that is cultivated on an increasing scale, with Spain, Chile and United States showing growing interest in its commercialisation. A comprehensive study of cherimoya in Loja Province realised from January 1996 till September 1999 gave valuable information for future crop development. Although cherimoya is very common, well known and appreciated all over the province, commercial cultivation has not yet developed and the trees are found in the wild or tolerated in farmers' gardens. Several trees showed better fruit quality characteristics than those of 'Fino de Jete', 'Bays', 'White', 'Bronceada' and 'Concha Lisa', which are commercialised on large scale. It is concluded that Loja Province possesses interesting germplasm accessions which should be used to develop local cherimoya growing and in international cherimoya improvement programmes.
 
In vitro micropropagation of S. cuminii . (A) Polyembryonic seed showing multiple seedling development 4 weeks post germination. (B) Phenotype of 6-week-old regenerated plantlet in hormone-free medium. (C) On medium supplemented with NAA (0.5μM), callus and roots appear at the base of the explant. (D) Multiple shoots formation from nodal explant cultured for 6 weeks on medium supplemented with BA (4.4 μM). (E) On medium supplemented with both BA (2.2 μM) and NAA (2.7 μM), callus is frequently formed at the base of the explant (see arrow). (F) Four-month-old culture in liquid medium supplemented with BA (4.4 μM). (G) Phenotype of 6-week-old regenerated plant with well-developed root system in presence of NAA 0.5 μM. (H) Two-years-old acclimatized plants. Scale bar = 1cm for A-G and 1 m for H. 
Effect of cytokinins (BA, 2iP, TDZ) and auxin (NAA) on axillary and adventitious shoot formation by S. cuminii node explants cultured for 6 weeks.
In vitro rooting of S. cuminii cultured for 6 weeks in medium supplemented with auxins (IBA or NAA).
Seeds of Syzygium cuminii (L.) Skeels are collected in Madagascar to prepare Madeglucyl®, a locally used antidiabetic preparation for type 2 diabetes treatment. For ex situ conservation of the Malagasy S. cuminii germplasm and to provide a continuous seed supply, a simple procedure for its in vitro clonal propagation was established. Nodal stem segments from in vitro raised 10-week-old seedlings were cultured on half-strength Murashige and Skoog medium (½MS) supplemented with various cytokinins, benzyl-aminopurine (BA), thidiazuron (TDZ) and N6-(2-isopentenyl) (2iP) adenine, at different concentrations and in combination with an auxin, α-naphthalene acetic acid (NAA). The most effective hormone concentration for shoot multiplication from axillary buds was 4.4 μM BA, providing an average of 7.5 shoots per node after six weeks of culture. In liquid medium, cultures could be maintained without subculturing for more than 4 months and yielded an average of 6.9 shoots per explant. The in vitro-propagated shoots produced adventitious roots when transferred to ½MS medium supplemented with either indole-3-butyric acid (IBA) or NAA. The best rooting was obtained in medium supplemented with 0.5 μM NAA with almost 90% of the plantlets developing an average of 5.9 adventitious roots per shoot. More than 70% of the rooted plantlets were successfully established in soil and showed uniform growth. At present, the plants are ready to be transferred for in situ cultivation to produce seeds for commercial purpose.
 
effect of three disinfection protocols on infection of three types of explants from L. secundiflorum.
effect of bap and naa on direct formation of shoots from two types of explants of L. secundiflorum after an eight-week incubation period.
A study was conducted to develop a protocol for mass-propagation of an economically important rattan species [Laccosperma secundiflorun (P. Beauv.) Kuntze] using leaves, axillary bud, and apical meristem explants collected from natural stands. The explants were incubated on basal MS (Murashige & Skoog 1962) medium containing vitamins (MSV), supplemented with different concentrations and combinations of 6-benzylaminopurine (BAP) and α-naphthaleneacetic acid (NAA). Best results (100% vigorous explants) from initiation phase were obtained after four weeks with axillary bud and apical meristem explants cultured in darkness at 28 ± 2°C on MSV supplemented with 30 g L−1 sucrose and 0.65 mg L−1 BAP. MSV containing 1 mg L−1 BAP and 1 mg L−1 NAA allowed highest rates of explants forming shoots (> 85%), with a mean of 3 shoots per explant after eight weeks. A high rate (> 95%) of shoots generated well-developed roots after two weeks on MSV containing 0.5 mg L−1 3-indoleacetic acid (IAA).
 
Wild apple (Malus sylvestris Mill.) is a woody species native to Europe. It is considered to be rare and potentially endangered in a significant part of its natural range. In order to evaluate its current geographic distribution in Belgium, an inventory was conducted throughout the country. The most important results related to habitat characteristics and tree and fruit phenotypic traits. The natural populations were identified using fruit diameter and leaf hairiness. The inventory indicated that, based on reference morphological characters, wild apple is indeed rare and endangered in the northern part of Belgium, but more common in the south. At the growth sites, trees identified as wild apple were mixed with varying proportions of hybrid or cultivated forms, depending on the habitat. This paper presents suggestions for the development of a genetic conservation strategy for wild apple.
 
Aquatic macrophytes constitute a major component of lagoon ecosystems. These ecosystems show high primary productivity mainly as a result of the aquatic macrophyte community. The relationship between macrophyte abundance and water quality parameters was examined in six coastal lagoons of western Greece. In a total of 24 selected sampling sites, water depth, transparency, temperature, pH, DO, salinity and conductivity were measured. All the lagoons showed seasonal variations in water quality parameters and significant fluctuations of DO and salinity were observed in the Araxos lagoon. Seven macrophyte groups were identified by TWINSPAN analysis and NMDS. A CCA showed that depth and salinity play a key role in the presence or absence of species and in the structure of macrophyte assemblages. The findings may contribute to a better management strategy of lagoon ecosystems of Greece.
 
Effects of fructose (A, B), glucose (C, D) and sucrose (E, F) on protonemal diameter and index of multiplication in in vitro cultures of B. argenteum and A. undulatum. The values plotted on the graphs represent the mean value of 40 measurements and the vertical bars represent the standard deviation.
The effect of different sugars (sucrose, fructose and glucose) on morphogenesis of two moss species, Bryum argenteum Hedw. (Bryaceae) and Atrichum undulatum (Hedw.) P. Beauv. (Polytrichaceae) in in vitro culture was tested. In vitro cultures of these two moss species were established from disinfected spores on Murashige and Skoog (MS) medium. Apical shoots of well-developed gametophytes were used to investigate the influence of different concentrations (0.01 M, 0.03 M, 0.05 M, 0.1 M, 0.2 M, 0.3 M) of sugars on secondary protonemal and gametophyte growth and multiplication. In in vitro culture of B. argenteum sugars had a positive influence on protonemal development and shoot multiplication, while in in vitro culture of A. undulatum these two processes were negatively correlated with addition of all tested sugars. Although all exogenous sugars tested affected developmental processes in B. argenteum and A. undulatum in in vitro conditions, these two moss species reacted differently.
 
Location of the river Orne, the reservoir of Rabodanges and the studied stretches (S0 to S6) around the hydroelectric reservoir. 
The two different sampling strategies for the study of P. pectinatus at the community level (right) and at the P. pectinatus stands level under powering effects (left). Two relevés per summer except in 1998 (one relevé in September). 
Restitution flows in the river Orne for the 1995-1998 period at the hydroelectric dam of Rabodanges (missing data were from January 1995 to May 1995 and from November 1995 to February 1996). 
Factorial plan of the Canonical Correspondence Analysis with forward selection of the significant environmental parameters. Four years (1995-1998) of floristic samples are represented by points (same surveyor). O symbols represent the projections in the factorial plan of the three water plants considered. 
Percentage cover of the three abundant taxa (two Spermatophyta and one macroalgae) of the restitution channel over the twelve years survey. Arrows indicate the date of the hydraulic management change. 
Potamogeton pectinatus L. is a submerged angiosperm with a cosmopolitan distribution, considered as a troublesome aquatic weed. It is prevalent in standing waters, withstands fast currents and can occur in powered sections downstream from high hydroelectric dams. An increase of regulated flow from 0.1 to 0.8 m3 s−1 was performed at the hydroelectric dam of Rabodanges (Normandy, France) for restoration ecology purposes, e.g. the rehabilitation of salmonids in the short-cut section. In order to assess the effect of this operational management of the hydroelectric dam, a macrophyte-based survey was done. Particular attention was paid to monotypic stands of P. pectinatus in the downstream channel of the dam since 1986. Continuous hydraulic and physicochemical data allowed the estimation of their effect on the stands of P. pectinatus. The importance of the changes of clumps of P. pectinatus at the level of the river Orne around the reservoir was compared to other macrophytes with a similar extend capacity: Cladophora sp. and Myriophyllum spicatum. P. pectinatus and M. spicatum showed a similar strategy. At a local scale, in a restitution channel, the variation of P. pectinatus cover was recorded in the context of the changing regulated regimes. After a decrease of the cover of clumps there was a progressive recovery to the initial stands cover. With observations over a twelve-year period, we confirmed the ecological plasticity of this plant in powered channels and highlighted the importance of long term survey in river restoration ecology.
 
The morphological plasticity of Laboulbenia flagellata Peyr., obtained from Agonum spp. (Pterostichini, Carabidae) and Loricera pilicornis (Fabricius) (Loricerini, Carabidae), was studied using multiple thallus measurements and statistical analysis. All variables were highly inter-correlated with thallus length. There was no complex polymorphism as the proportions of thalli were stable. Thallus length was statistically different in relation to host species, habitat type and growth position. The results suggest that environmental factors affect thallus growth and final size of mature thalli. The smallest mature thalli of L. flagellata come from Loricera pilicornis, their thallus length was remarkably constant.
 
Invasiveness of two exotic species, Chromolaena odorata (Asteraceae) and Hyptis suaveolens (Lamiaceae), in relation with land use around Bétécoucou (Bénin). Very few studies have been conducted on the effects of farming systems on the invasive capacity of exotic species. This study fills this gap by analysing the invasive capacity of two exotic species, Chromolaena odorata and Hyptis suaveolens, in farming systems in the Guineo-Congolian/Sudanian transition zone of Benin. The findings show that the annual seed yield of C. odorata (45 151 seeds/plant) is significantly higher than that of H. suaveolens (1 782 seeds/plant). On the other hand, seed germination rate of H. suaveolens (70%) was higher than that of C. odorata (30%). Seed production and population density of C. odorata were higher in fallows and tree-savannah than in deforested savannah and croplands. H. suaveolens seed production and population density were higher in fallows and degraded savannahs. Bush fire reduced plant growth, the amount of seeds annually produced, and the seed germination rate. This study shows that the invasion intensity is related to the farming system. These two exotic species unfavourably altered the vegetation structure available to livestock by favouring the establishment non-forage species. French Les effets du type d'exploitation agricole sur les capacités d'invasion des espèces exotiques sont rarement étudiés. La présente étude a pour objectif d'analyser les capacités d'invasion de deux espèces exotiques, Chromolaena odorata et Hyptis suaveolens, en relation avec l'exploitation des terres dans la zone de transition guinéo-congolaise/soudanaise du Bénin. Les résultats indiquent que la production annuelle des graines de C. odorata (45 151 graines/individu) est plus élevée que celle de H. suaveolens (1 782 graines/individu). En revanche, le taux de germination de H. suaveolens (70%) est plus élevé que celui de C. odorata (30%). La production de graines et la densité des individus de C. odorata sont plus élevées dans les jachères et les savanes arbustives-arborées pâturées que dans les savanes déboisées et champs de culture. Celles de H. suaveolens sont plus élevées dans les jachères et les savanes déboisées. Le feu de végétation a contribué au ralentissement du développement de leurs plants et à la réduction de leur production de graines et de leur taux de germination. L'étude révèle que le degré d'invasion est lié aux perturbations anthropiques des types de formations végétales. Hyptis suaveolens présente une capacité d'invasion plus élevée que C. odorata. Les deux plantes exotiques modifient la structure des formations végétales dans un sens défavorable à l'élevage en induisant l'installation des espèces non appétées par le bétail.
 
Eleven new chromosome counts in 10 Turkish endemic Centaurea species in section Phalolepis are reported. The prevalence of the basic chromosome number of x = 9, together with a close correlation between karyological data and classification of the eastern sections of the Jacea group, is confirmed. According to our counts, polyploidy, and especially tetraploidy, occurs in Phalolepis section and seems to be an important factor for diversification in this section of the genus Centaurea.
 
Dispersion capacity of alien invasive plants is a key feature for understanding invasion processes and risks. Here, we present an experimental study focussing on the seed rain pattern of Senecio inaequidens, an African plant widespread throughout Europe, under common favourable dispersal conditions. One hundred achenes from two Belgian populations underwent a drop time in still air experiment in order to assess linear correlation between several morphological traits and terminal velocity. Variation in morphological traits was measured for 250 additional achenes per population. The trait best correlated to terminal velocity was the square root of the plume loading. We then used this trait to model terminal velocity using a linear regression (r2 of 79.7%). With this regression and imposing ecological parameters such as wind speed, turbulences and height of release to be representative of favourable dispersal conditions, we established a Gaussian tilted plume model to predict the seed rain pattern of the species. Awind tunnel experiment consequently permitted to validate the model. Under a wind speed of 5 m s-1 with 2% turbulences along the vertical axis, and height of release of 0.40 m, 99.8 % of achenes were dispersed within 100 meters, with a maximum deposition rate at 5.2 m from the parent plant. Uplifted achenes, not forecasted by the model, represent 6.25% of all achenes.
 
A new record of the genus Astragalus L. (A. wagneri Bunge) is given from East Anatolia ; it is compared with the related species A. dictyophysus Reuter ex Bunge. On the other hand, a taxon previously considered in Turkish Flora as a synonym, A. lycaonicus Hub.-Mor. & Reese is reevaluated as a distinct species ; a discussion of the taxonomy of this species and the related A. mesogitanus Boiss. is provided. A full description and an illustration of A. wagneri and a description of A. lycaonicus are given. A distribution map of the four species in Turkey is produced.
 
In order to monitor atmospheric fluoride pollution, epiphytic lichens (Parmelia sulcata) were collected in a rural area and transplanted to two fluoride point sources (Genk and Beerse) and one reference location (Diepenbeek). In Genk and Beerse, lichens were installed at various distances from the source. In Diepenbeek, lichens were only transplanted to one station. Fluoride concentrations in ambient air were measured close to the lichen transplants placed closest to the fluoride source. Lichen vitality parameters (i.e., lichen colour and algal vitality) together with fluoride and trace element concentrations were measured just before transplantation, and 6 and 12 months after transplantation. Before transplantation no fluoride was detected in P. sulcata samples (< 5 mg F− kg−1). In Genk fluoride concentrations in lichens gradually increased up to 134 mg kg−1 after 12 months. In Beerse transplants contained 243 mg F− kg−1; all transplants were killed close to the fluoride source after 6 months. Besides fluorides, increased Cu concentrations were found in these lichens. Furthermore, SO2 emission was substantially higher in Beerse compared to Genk and Diepenbeek, which makes it difficult to conclude whether lichens close to the source in Beerse were killed because of fluorides alone, or a combination of fluorides, Cu and/or SO2. At both locations fluoride concentrations in lichens substantially decreased at 2 km distance from the source, confirming the relatively local character of atmospheric fluoride pollution.
 
Fruits du cultivar 53 collecté à Tohoun. Uniformité des fruits après la deuxième année de reproduction sur le site expérimental de Sékou (crédit : R.S. Vodouhe).
Cercle de corrélation des variables du fruit. flf : date de floraison femelle, flm : date de floraison mâle, clf : couleur fleur, laf : largeur du fruit, lof : longueur du fruit, pmf : poids moyen du fruit, nfp : nombre moyen de fruits par plant, lpe : longueur du pédoncule, frg : nombre de fruit en forme de gourde, frc : nombre de fruits cylindriques, frr : nombre de fruits ronds, frv : nombre de fruits verts, frd : nombre de fruits en forme de petites gourdes, fra : nombre de fruits allongés, fre : nombre de fruits évasés, frb : nombre de fruits blancs, fvt : nombre de fruits vert tacheté.
Variabilité phénotypique au niveau des graines de Lagenaria siceraria (crédit : E.G. Achigan-Dako).
Cercle de corrélation des variables des graines. dur : dureté de la graine, rlg : rainures longitudinales sur la graines, cog : couleur de la graine, coh : aspect du hile, fob : forme de la base, lag : largeur de la graine, ail : présence d'ailes sur la graine, emp : présence d'empâtement, coa : couleur de l'amande, laa : longueur de l'amande, mog : forme du sommet, epg : épaisseur de la graine, txt : texture du tégument, log : longueur de la graine, loa : longueur de l'amande.
Cercle de corrélation de l'analyse combinée entre descripteurs des fruits et des graines. flf : nombre de jour à la floraison femelle, flm : nombre de jour à la floraison mâle, lof : longueur du fruit, laf : largeur du fruit, pmf : poids moyen du fruit, nfp : nombre moyen de fruits par plant, lpe : longueur du pédoncule, dur : dureté de la graine, cog : couleur de la graine, lag : largeur de la graine, epg : épaisseur de la graine, log : longueur de la graine.
Morphological characterisation of cultivars of Lagenaria siceraria collected in Benin and Togo. Lagenaria siceraria (bottle gourd) belongs to the Cucurbitaceae family for which more than 825 species have been recorded. It is a multipurpose species used for food, cultural purposes, kitchen utensils, decoration, music instruments, etc. Although the species has many uses, it is overlooked by scientists and development agents while genetic erosion is taking place. In this study we analysed and described the morphological variability of 60 accessions coming from 13 cultivars collected in Togo and Benin. We used in total 32 descriptors but only 12 of them contributed significantly to a good clustering of the accessions. These are: number of fruits per plant, average weight of fruit, date to flowering (male and female), peduncle length, fruit size and shape, seed length and width, seed thickness, seed colour and hardness. Principal Component Analysis (PCA) and Cluster Analysis allowed distinguishing three groups. The first group gathers together cultivars 34, 35, 37, 38, 40 and 54 collected in Central and Northern Togo and known as `Savalou' by local people. The second group is made up of cultivar 53 known as `Sogoé' in Southern Togo and cultivars 47 and 51 from Southern Togo known as `Tigoé'. The third group includes two cultivars (46 and 48) from Southern and Northern Togo known as `Ka' in Benin and cultivars 56 and 58 (known as `Kplakata' or `Go') collected in Central Benin. French Lagenaria siceraria (gourde) appartient à la famille des Cucurbitaceae qui regroupe plus de 825 espèces répertoriées de part le monde. C'est une espèce à usages multiples dont les fruits sont utilisés comme aliment, ustensile de cuisine, instrument de musique, etc. Le manque d'information sur les gourdes de l'Afrique de l'Ouest et l'absence de stratégie adéquate de conservation peut conduire à une érosion génétique des cultivars locaux. Dans cette étude, la variabilité morphologique au sein de Lagenaria siceraria a été décrite et analysée. Soixante accessions provenant de 13 cultivars locaux collectés au Bénin et au Togo ont été semées et décrites. Des trente-deux caractères observés et mesurés sur toutes les accessions, douze se sont révélés discriminants. Il s'agit de la date à la floraison mâle et femelle (50%), la longueur du pédoncule, la longueur et la largeur des fruits, le nombre de fruits par plante, la forme des fruits, la longueur et la largeur des graines, l'épaisseur, la couleur et la dureté des graines. L'Analyse en Composantes Principales (ACP) et la Classification Ascendante Hiérarchique (CAH) ont permis de distinguer trois groupes de cultivars. Le premier est le groupe `Savalou' qui réunit les cultivars 34, 35, 37, 38, 40 et 54 collectés au Centre et au Nord Togo. Le second groupe rassemble les `Sogoé' (cultivar 53 collecté au Sud Togo) et les `Tigoé' (cultivars 47 et 51 du Sud Togo). Le troisième groupe est celui des `Ka', cultivars 46 et 48 prospectés au Sud et au Nord Togo et celui des `Kplakata' et `Go' du Centre Bénin.
 
Kosteletzkya virginica exhibits a delayed autonomous selfing mechanism by stigma lobe curvature. To measure the contribution of delayed selfing to reproductive success in a naturalised population of K. virginica, we evaluated the capacity for autonomous self-pollination and compared reproductive success of intact with emasculated open-pollinated flowers. We found no significant differences in the mean number of pollen grains deposited per flower and per stigma between the autonomously pollinated and open-pollinated flowers. There were no significant differences in mean fruit set and in mean number of seeds per capsule between autonomous and hand self-pollination. Fruit set following self-pollination varied significantly depending on the timing of pollination within a day. Emasculation and pollination treatments did not significantly affect fruit set. In contrast, the mean number of seeds per capsule from intact open-pollinated flowers was higher than that of emasculated open-pollinated flowers. These results indicate that K. virginica has a well-developed capacity for delayed autonomous selfing, which increased seed production in the study population.
 
(A) Physiognomy of a landward Avicennia marina fringe in Gazi, Kenya. (B) Overview (B1) and close-up (B2) of an A. marina tree uprooted by tidal and wave energy. (C) Close-up of A. marina pencil-roots and of the micro-topographic variations (note the pathway of the incoming tide). (C) Path amongst A. marina pneumatophores created by walking fisherfolk. (Photographs taken by Griet Neukermans and Farid Dahdouh-Guebas)  
(a-b) Micro-topography and above-and below-ground pneumatophore length, and (c-d) pneumatophore density for Avicennia marina sampled across a depression at 1 m intervals along a landward and a seaward mangrove transect.
Mangroves are known to stabilise coastal sediments through their aboveground aerial root complex. The results presented in this paper suggest that the grey mangrove Avicennia marina has the ability to adapt its pneumatophores to micro-topographical irregularities in the otherwise regularly sloping intertidal zone. The difference in height above datum (and thus in hydrological regime) in this study was as little as 15 cm higher as opposed to that for the surrounding mangrove soil. Significantly higher pneumatophore densities and total pneumatophore lengths were observed in the centre of the landward depression, and significantly lower belowground pneumatophore length in the centre of the seaward depression. The mangrove's adaptations to these localised topographic differences are important in view of changes in intertidal hydrology, the latter being linked to changes in topography. We emphasize the need to consider the effect of topography in the intertidal environment of mangroves more closely in the future on different ecological scales (individual adaptation - regeneration of the entire population) and under different scenarios of change (direct anthropogenic impact - changes in sea level).
 
The current natural distribution of Taxus baccata L. in Belgium is limited to a few localities in the southern part of the country. In these localities, Taxus is predominantly growing on steep, calcareous slopes, which is believed to be its natural habitat in this part of the world. In Flanders, the northern part of Belgium, Taxus is considered not to be native and Taxus stands are interpreted there as being planted by humans or as garden escapes. The Holocene pollen and macrofossil data for Taxus, however, show a very different picture regarding abundance and geographical distribution, as well as habitat. It appears that during the Sub-boreal, Taxus grew in the coastal plain and the lower Scheldt valley, where it was part of the carr vegetation on peat. Before the end of the Sub-boreal, Taxus seems to have disappeared from this region, most probably because of the transition from the carr vegetation to (raised) bogs. Belgium is not the only case where such observations have been made. In other areas of northwestern Europe, Taxus also seems to have had a completely different distribution and ecology in the past, especially during the Sub-boreal. An overview of the palaeobotanical finds of Taxus baccata from Belgium is here given, supplemented with finds from neighbouring regions. The Holocene distribution and palaeo-ecology of Taxus baccata are discussed in a broader northwest European context.
 
During a survey of a small freshwater pond enclosed by the Herbarium building of the National Botanic Garden of Belgium, two new species belonging to the genera Eunotia and Encyonopsis have been found. The morphology of both species is discussed using both light and scanning electron microscopical observations and compared with similar species. Eunotia belgica is similar to E. glacialifalsa but can be separated based on its valve dimensions (larger valve width), number of striae, the absence of the characteristic longer cell cycle stages of E. glacialifalsa and a different striation pattern. Encyonopsis horticola belongs to the E. microcephala complex but can be differentiated from other members of this complex by a combination of valve outline, striation pattern and areolae structure.
 
-Jack pine (Pinus banksiana) range in Quebec (light grey area, modified from LITTLE 1971) showing the 15 populations studied. The northwestern group is represented by white rectangles, while the eastern group is represented by black rectangles.
In this study we investigated the genetic structure and diversity of jack pine populations in Quebec using chloroplast microsatellite markers. Six cpSSR loci were used to screen 15 Pinus banksiana populations from an economically important region of the boreal zone. The main objective was to quantify the variation within and among populations and to relate this to their geographic pattern. From 3 to 6 size variants were identified at each locus. A total of 29 size variants at the six loci were identified and 5 of the size variants occurred infrequently. The size variants were combined into 87 different haplotypes, of which 49 were unique. The AMOVA analysis revealed that 10.96% of the variation was distributed between populations and 89.04% within populations. Cluster analysis divided the studied populations into two large groups, one from north-western Quebec and the second from eastern Quebec. These results suggest that the genetic structure of the studied jack pine populations is the result of interactions between historical post-glacial migrations and climate-disturbance structuring factors.
 
Encephalartos barteri ssp. barteri (Zamiaceae) is a cycad endemic to Benin, Nigeria, Ghana and Togo. The species is considered as vulnerable in its area of distribution. In the present study, we analysed the patterns of leaflet morphological variation and the genetic variability within and among five populations sampled in Benin, between 7°34' and 10°20'N. Leaflet morphology showed significant variation among populations. The differences observed among populations were not correlated with geographic distances. Sixteen Random Amplified Polymorphic DNA (RAPD) primers with a total of 133 scorable bands (82.7% polymorphic) were tested. Three primers generating 32 consistently and wellamplified bands were used to characterise the 150 individuals sampled. High levels of genetic diversity were observed (P = 93.75%, HE = 0.297 at the species level, and P = 75%, HE = 0.228 at the population level). Two population-specific bands with high frequencies were found. There was also evidence of high differentiation among populations (GST = 0.2313, ΦST = 0.3236, p < 0.001). Cluster analysis corroborated the previous results and mainly grouped the individuals and populations according to their geographic origin.Current patterns of morphological and genetic variation in E. barteri ssp. barteri appear to reflect interactions amongst a range of factors namely, past climate changes, phenotypic plasticity, local adaptation, geographic isolation and limited seed dispersal/pollen transfer. Conservation strategies are discussed: urgent actions need to be taken to protect the populations (Gangamou and Doh) not having any legal protection status but containing unique genetic variants, and community-based nursery management should be envisaged. Finally, given the ongoing decline of the habitat of the species and the continued removal of individuals from the wild it is recommended that the IUCN Red List category for this species should be changed from vulnerable to endangered.
 
Viola calaminaria (Gingins) Lej. is a rare and threatened species, endemic to metalliferous soils in E Belgium, S Netherlands and W Germany. In order to provide basic information for a conservation strategy, we performed an ecogeographic survey of almost all V. calaminaria populations currently existing in Belgium. Twenty-four populations were found, distributed in three geographic groups all in the Province of Liège. The area covered by V. calaminaria ranged from < 1 m2 to 3.2 ha. The largest populations were found in sites contaminated by atmospheric deposits from metal smelters. Soils were extremely variable in heavy metal and nutrient concentrations, but concentrations of Zn, Pb and Cd were consistently higher than reference values for normal soils. V. calaminaria was most often found in association with other metallophyte and pseudometallophyte taxa typical of metalliferous sites. Plant communities identified by TWINSPAN analysis generally fitted the heavy metal associations previously described but two unusual heavy metal plant communities were identified. Based on a canonical correspondence analysis, pH was the only factor that was clearly correlated with the floristic composition of plant communities associated to V. calaminaria. This study confirmed the ecological endemic status of V. calaminaria and the importance of the conservation of metalliferous sites.
 
In Belgium, most calcareous grassland relics are associated with Devonian limestone substrates in the Viroin valley, which is part of the Calestienne region. Previously grazed by sheep, these grasslands are characterised by an extremely high species richness and many rare plant species. Despite their high biodiversity, a detailed phytosociological classification and an ecological description of the relics of these grasslands do not exist.In spring and summer of 2003, the calcareous grassland vegetation on Devonian limestone hills in the Viroin valley was inventoried. A total of 401 vegetation relevés were established in 1 m2 plots. Based on classification and ordination techniques seven vegetation types were distinguished. The main differences in species composition were explained by a gradient from xerophilous towards mesophilous environmental characteristics. The particular phytosociological and phytogeographical position of the calcareous grasslands in the Viroin valley is further discussed in a European context. Mesophilous calcareous grasslands in the Calestienne belong to the Mesobromion and show an intermediate position between the central European and the Atlantic calcareous grassland communities. The xerophilous calcareous grassland communities on the other hand show strong affinities with the calcareous vegetation of central Europe and southern Europe.
 
List of nomenclatural changes, with corresponding synonymies, since the previous check-list of the bryophytes of Belgium by SOTIAUX & VANDERPOORTEN (2001).
An amended checklist of the bryophytes of Belgium is presented. Although some taxonomic positions adopted in the most recent European checklist of mosses are discussed, the latter is used as a reference in an attempt to homogenize taxonomic concepts at a wide scale and enable comparisons across countries. Since the previous 2001 checklist of Belgian bryophytes, a total of 17 and 14 species must be added to the Belgian bryoflora owing to taxonomic changes and floristic discoveries, respectively. The report of Grimmia caespiticia, at an altitude of 500-600 m, is particularly noteworthy because this alpine species usually occurs above 2 000 m. Five additional taxa, Scapania cuspiduligera, Dialytrichia fragilifolia, Ephemerum cohaerens, Orthotrichum shawii and Tortella inclinata var. densa, are reported here as new to Belgium. Six species were previously erroneously reported from Belgium and are excluded. As a consequence, the bryophyte flora of Belgium consists of 748 species, including 5 hornworts, 173 liverworts, and 570 mosses whose occurrence in the three regions of Belgium, namely Flanders (5 hornworts, 122 liverworts, 399 mosses), Wallonia (3 hornworts, 169 liverworts, 546 mosses), and Brussels-Capital Region (46 liverworts, 196 mosses), is documented. Thirty-six species (6 liverworts and 30 mosses) have not been recorded since 1980 and are most probably extinct. The new checklist is used to update the list of European red list species that are present in Belgium, which now includes 49 species.
 
Top-cited authors
Francis C Yeh
  • University of Alberta
Tim Boyle
  • United Nations Development Programme
Martin Hermy
  • KU Leuven
Olivier Honnay
Lucien Hoffmann
  • Luxembourg Institute of Science and Technology (LIST)