:: E. DODINET & S. NADOT Editorial Paru dans Botany Letters, 2017, 164 (4), pp. 291-292. Anglais :: F. JABBOUR A study of the anatomy and physiology of nectaries: a translation of Gaston Bonnier’s seminal work (1878, Bulletin de la Société Botanique de France) Paru dans Botany Letters, 2017, 164 (4), pp. 293-302. Anglais Abstract To fuel the research on nectar and nectaries, I propose here an English translation of a seminal article published 140 years ago in the Bulletin de la Société Botanique de France, which was one of the former titles of the current Botany Letters. The reference of the original publication is: Bonnier, G. 1878. “Etude sur l’anatomie et la physiologie des nectaires.” Bulletin de la Société Botanique de France 25 (8): 262–271. doi: 10.1080/00378941.1878.10827912. The translated article is preceded by an introduction clarifying the scientific context, and followed by a synthesis of subsequent and recent studies about nectar and nectaries.
:: J. A. COETZEE, M. P. HILL, T. RUIZ-TÉLLEZ, U. STARFINGER & S. BRUNEL Monographs on invasive plants in Europe N° 2: Eichhornia crassipes (Mart.) Solms Paru dans Botany Letters, 2017, 164 (4), pp. 303-326. Anglais Abstract Eichhornia crassipes is notorious as the world’s worst aquatic weed, and here we present all aspects of its biology, ecology and invasion behaviour within the framework of the new series of Botany Letters on Monographs on invasive plants in Europe. Native to the Amazon in South America, the plant has been spread around the world since the late 1800s through the ornamental plant trade due to its attractive lilac flowers, and is established on every continent except Antarctica. Its distribution is limited in Europe to the warmer southern regions by cold winter temperatures, but it has extensive ecological and socio-economic impacts where it invades. Its reproductive behaviour, characterised by rapid vegetative spread and high seed production, as well as its wide physiological tolerance, allows it to proliferate rapidly and persist in a wide range of environments. It has recently been regulated by the EU, under Regulation No. 1143/2014, which states that E. crassipes shall not be brought into the territory of the Union, kept, bred or transported to, from or within the Union. However, in the absence of effective control measures, such as herbicidal and biological control, it will continue to be a significant threat to European waterways, particularly in eutrophic waters, and under future climate change scenarios.
:: L. T. DUNNING, A.-L. LIABOT, J. K. OLOFSSON, E. K. SMITH, M.S. VORONTSOVA, G. BESNARD, K. J. SIMPSON, M. R. LUNDGREN, E. ADDICOTT, R. V. GALLAGHER, YINGYING CHU, R. TOBY PENNINGTON, P.-A CHRISTIN & C. E. R. LEHMANN The recent and rapid spread of Themeda triandra Paru dans Botany Letters, 2017, 164 (4), pp. 327-337. Anglais Abstract Tropical savannas cover over 20% of land surface. They sustain a high diversity of mammalian herbivores and promote frequent fires, both of which are dependent on the underlying grass composition. These habitats are typically dominated by relatively few taxa, and the evolutionary origins of the dominant grass species are largely unknown. Here, we trace the origins of the genus Themeda, which contains a number of widespread grass species dominating tropical savannas. Complete chloroplast genomes were assembled for seven samples and supplemented with chloroplast and nuclear ITS markers for 71 samples representing 18 of the 27 Themeda species. Phylogenetic analysis supports a South Asian origin for both the genus and the widespread dominant T. triandra. This species emerged ~1.5 Ma from a group that had lived in the savannas of Asia for several million years. It migrated to Australia ~1.3 Ma and to mainland Africa ~0.5 Ma, where it rapidly spread in pre-existing savannas and displaced other species. Themeda quadrivalvis, the second most widespread Themeda species, is nested within T. triandra based on whole chloroplast genomes, and may represent a recent evolution of an annual growth form that is otherwise almost indistinguishable from T. triandra. The recent spread and modernday dominance of T. triandra highlight the dynamism of tropical grassy biomes over millennial time-scales that has not been appreciated, with dramatic shifts in species dominance in recent evolutionary times. The ensuing species replacements likely had profound effects on fire and herbivore regimes across tropical savannas.
:: L. GIANGUZZI, A. D’AMICO & A. TROIA Notes on the distribution, ecology and conservation status of two very rare sedges (Carex, Cyperaceae) rediscovered in Sicily (Italy) Paru dans Botany Letters, 2017, 164 (4), pp. 339-349. Anglais Abstract New data on the geographical distribution and ecology of two rare taxa of Carex collected in the area of the Nebrodi Mountains (Sicily) are provided; the Sicilian populations of both taxa are at the border of their respective ranges, and their regional distribution is still poorly known. The new population of Carex × boenninghausiana reported here confirms the presence of this hybrid in Sicily, but at the same time it represents the only known population currently occurring in Italy; in fact, the other – so far only – known Italian population is considered extinct. The second report concerns Carex grioletii, recently considered doubtful for the Sicilian flora, whose new population here reported is the only confirmed and currently present population in the island; the assessment of extinction risk and conservation status, carried out at regional (Sicilian) level according to the IUCN criteria for the latter taxon, showed that it is Critically Endangered (CR).
:: P. DANTON & C. PERRIER Suppressions and additions to the flora of the Juan Fernández archipelago (Chile) Paru dans Botany Letters, 2017, 164 (4), pp. 351-360. Anglais Abstract Supplement to the Nouveau catalogue de la flore vasculaire de l’archipel Juan Fernández, Chili (Danton and Perrier 2006), this paper presents the taxa (61) that can be today removed from the list of the plants present in the archipelago and those (68) that must be added since the publication of our Nouveau catalogue.
:: M. BAKHA, C. AL FAIZ, M. DAOUD, N. EL MTILI, K. ABOUKHALID, A. KHIRAOUI, N. MACHON & S.SILJAK-YAKOVLEV Genome size and chromosome number for six taxa of Origanum genus from Morocco Paru dans Botany Letters, 2017, 164 (4), pp. 361-370. Anglais Abstract The majority of the Origanum species are important medicinal plants as well as culinary herbs and have thus a great economic value. Some taxonomic issues are still pending within the genus and the cytogenetic studies about this genus are still very scarce. Therefore, studies concerning chromosome number and genome size can provide complementary data that may be useful to characterize the genus Origanum. These two approaches have been used to characterize five Moroccan taxa of the genus Origanum occurring in the wild in addition to the exotic species O. onites. All investigated taxa are diploid with chromosome number of 2n = 30. This is the first time the chromosome numbers have been counted in O. grosii, O. compactum and O. × fontqueri as well as in O. vulgare subsp. virens from Morocco. The genome sizes are considered as small, and the mean values ranged from 1.43 pg/2C in O. vulgare subsp. virens to 1.53 pg/2C in O. compactum. Besides, no significant intraspecific variability in genome size was observed among populations of O. elongatum as well as of O. grosii.
:: R. RAMÍREZ-RODRÍGUEZ & F. AMICH Effects of local abundance on pollination and reproduction in Delphinium fissum subsp. sordidum (Ranunculaceae) Paru dans Botany Letters, 2017, 164 (4), pp. 371-383. Anglais Abstract Delphinium fissum subsp. sordidum (Ranunculaceae) is an endangered, xenogamous, selfcompatible hemicryptophyte endemic of the central-western Iberian Peninsula, with a disjunct distribution in the Sierra Mágina (Spain: Jaén Province). We studied the effects of local abundance, in terms of plot size (number of individuals) and plot purity (relative abundance), assessing the activity of pollinators (frequency of visits and behaviour of visitors), quantity and quality of pollinator services and seed set in two populations. Flowers of D. fissum subsp. sordidum were visited by Hymenoptera (88.8%), Lepidoptera (10.3%) and Diptera (0.9%). The most frequent pollinator was Bombus terrestris (72.6% of total visits). Differences in relative frequency of visits to plants were observed between populations. Plots with high numbers of individuals attracted more pollinators. The same pattern was observed for stigmatic pollen loads and seed set; 99.46% of pollen grains deposited on the stigmas were conspecific, and the main competitor was Ferula communis. The effects of purity were assessed by comparing pure plots with a mixed plot that included plants that coincide with the flowering stage of D. fissum subsp. sordidum and exert an effect of interspecific competition. These results may be useful for developing conservation measures, especially in the small population of Aldeadávila.
:: A. ABOZEID, J. LIU, Y. LIU, H. WANG & Z. TANG Gas chromatography mass spectrometry–based metabolite profiling of two sweet-clover vetches via multivariate data analyses Paru dans Botany Letters, 2017, 164 (4), pp. 385-391. Anglais Abstract The sweet-clover vetch (Vicia pulchella) is generally a forb or herbaceous species native to the United States, used in farming as a forage plant. In this study, we examined the seeds of the two subspecies of Vicia pulchella, V. pulchella subsp. pulchella Kunth and V. pulchella subsp. mexicana (Hemsl.) C.R.Gunn using gas chromatography-mass spectrometry coupled with multivariate data analyses to discriminate between the two subspecies via their chemical profiles. The metabolic differences of seeds derived from seven accessions belonging to the two subspecies were assessed. Eighty-two metabolites and derivatives, including 21 amino acids and other 13 nitrogen containing compounds, 8 sugars, 2 sugar alcohols, 17 organic and inorganic acids, 6 fatty acids, 4 glycosides and other compounds, were identified. All the replicates of all accessions examined for each subspecies were clustered together via principal component analysis and hierarchical clustering analysis. In general, V. pulchella subsp. pulchella presented more amino acid and fatty acid contents, while higher levels of sugars and organic acids were identified in V. pulchella subs. mexicana. Although our results confirmed that the species could provide a good set of nutritive compounds for livestock, a significant number of bioactive compounds, such as free amino acids and hydroxy fatty acids, which could have a toxic effect on the livestock and limit the potential role of the plants in the farming system, were also detected.
:: J. X. LIAO, H. ZHANG, L. MO, Y. Q. HUANG, Y. J. SUN & Y. Q. LI Differences in growth and biomass allocation of Adiantum flabellulatum and A. capillus-veneris as a result of light and water availability Paru dans Botany Letters, 2017, 164 (4), pp. 393-400. Anglais Abstract Most Adiantum species favor shaded and moist conditions, but A. flabellulatum prefers ample sunlight. To better understand such differences and elucidate possible ecophysiological mechanisms, we grew A. flabellulatum and A. capillus-veneris, a famous indoor ornamental species, under three light (360, 180, and 90 μmol photons m-2 s-1) and two soil moisture (15.5 and 10.3% w/w) conditions and compared their dry matter production and allocation, leaf traits, and relative growth rate (RGR). For A. flabellulatum, reduced light availability significantly increased chlorophyll (Chl) content but decreased total mass and RGR. In A. capillus-veneris, total leaf area (LA), specific leaf area (SLA), and leaf area ratio (LAR) increased, but total mass and RGR did not differ as light availability decreased. Under drought stress, both species decreased LA, LAR, and Chl content. However, A. flabellulatum increased root allocation, and its total mass and RGR remained almost unaffected, whereas in A. capillus-veneris, biomass allocation did not change but total mass and RGR decreased significantly. Relative to A. capillus-veneris, A. flabellulatum exhibited lower LA, SLA, LAR, Chl content, and RGR under the same conditions, but higher root allocation, lower leaf allocation, and similar RGR under high light and drought conditions. These results suggested that different adaptive strategies exist between the two species. A. flabellulatum is relatively superior in drought tolerance but inferior in shade tolerance, allowing it to persist in habitats with low soil moisture and high light availability. A. capillus-veneris can capitalize on available resources and hence promote its growth in low light canopy conditions.
:: I. PAUŠIČ, M. KALIGARIČ & B. BAKAN Late seasonal mowing enhances central European Spiranthes spiralis (L.) Chevall. (Orchidaceae) population viability Paru dans Botany Letters, 2017, 164 (4), pp. 401-412. Anglais Abstract Flowering in many orchids is determined by the resource status of plants, which in turn is influenced by habitat management. Most European orchids require high light intensities for photosynthesis, failing to flower and fruit at low light levels. Agricultural practices, especially fertilisation and mowing/grazing regime, can therefore influence the fitness and reproductive success of orchids. The studied species, autumn lady’s-tresses (Spiranthes spiralis), is a small, long-lived and late-flowering perennial orchid and one of the most sensitive to low light availability. The general species’ fitness, measured as a set of robust morphological traits in relation to vegetation height, which directly reflect the time of the last seasonal mowing and so the light availability, was the main scope of this research. A total of 2442 flowering exemplars (of which 427 were morphologically evaluated) were recorded on 26 grassland patches applying the systematic scanning of the potential growing sites in the Goričko Natural Park (NE Slovenia). We revealed that earlier mowing negatively affects the density of flowering individuals and plant fitness in general. The number of the rosette leaves was found to be the most important trait that could be used as a proxy for the general plant fitness of this orchid species because the significant positive correlation with the measured morphological traits was confirmed. The number of the rosette leaves shows a significant negative relation to vegetation height. Late seasonal mowing, which has a significant positive impact on the plant fitness, enhances Spiranthes spiralis population viability and density.
:: C. CHAUDRON & F. ISSELIN-NONDEDEU Assessing the effects of mowing machinery on seed dispersal pattern: a test of two methods of seed tracking Paru dans Botany Letters, 2017, 164 (4), pp. 413-423. Anglais Abstract Seed dispersal is a key process that humans can influence in various ways. However, this type of interaction is less studied than dispersal by other animals. In addition, tracking seeds to determine dispersal pattern is a complicated task. We explored the effects of mowing machinery on seed dispersal in roadsides by testing two methods, (i) by marking fruits and diaspore of plants within the standing vegetation (ii) by making fake plants containing estimated quantities of marked seeds. We measured the pattern of dispersal by considering each seed and the centre of seed shadows of each species calculated by two means (i.e. the centroids and the gravity centres). We estimated the distance of dispersal from roadsides, and the deviation angle from the direction of the mowing. We then analysed the variation in dispersal patterns among species, seed mass and width/length ratio by using correlation tests. Seeds coloured within the standing vegetation were detected from 0.5 to 15.51 metres away from roadsides, with deviation angles from the mowing machinery ranging from –153.43° to 161.57°. With the other method we found a mean distance of dispersal ranging from 0.5 to 13.01 metres and deviation angle from –168.69° to 180°. We did not find strong variation in dispersal patterns among species and seed traits, but we demonstrated however that mowing machinery influenced both dispersal distance and deviation angles.
:: K. YESSOUFOU Potential carbon stock in the Kruger National Park, South Africa Paru dans Botany Letters, 2017, 164 (4), pp. 425-432. Anglais Abstract Global concern about climate change motivates for increasing interests in revising the management plan of natural ecosystems to include carbon sequestration services. Such revision must be informed of knowledge of carbon storage capacity of these ecosystems and the underlying factors. Here, the aim is twofold: to quantify the carbon stock that could be expected from the diversity of trees (~500 species) in the Kruger National Park (KNP; ~2 million ha) if all individual trees recorded in 110 plots of 50 m × 50 m grow to their maximal potential; and to test the predictive power of several potential correlates of the physiology of carbon storage. The results indicated the KNP is a potential reservoir of ~2 × 108 tonnes of carbon with a total mean density (above + below-ground carbon) of ~105 tonnes ha−1, a carbon density comparable with that of many other natural systems. Carbon storage in the KNP did not correlate with phylogeny and species abundance, but did so with phenology and wood density. However, only 4% of the variation in carbon storage was explained, indicating that key determinants of carbon storage are missing in this analysis. Although this study suffered a number of limitations that are presented, the expectation from this study is that it would raise increased interests into the potential of carbon stocked in the KNP in South Africa as one of the key diverse services this park provides beyond biodiversity conservation.
:: B. E. L. CERABOLINI, G. BRUSA, R. M. CERIANI, S. ARMIRAGLIO, C. DE MOLLI & S. PIERCE Ecology and floristic composition of heathlands in the Po basin and the Southern Alps (NW Italy) Paru dans Botany Letters, 2017, 164 (4), pp. 433-444. Anglais Abstract The importance of heathlands as habitats for plants and thus for nature conservation is recognized by European Directive 92/43 (Habitats Directive). However, heathlands are threatened by habitat loss and quality degradation due to several drivers. Temperate Calluna vulgaris communities in the Po basin and in the Southern Alps (NW Italy) are disjunct from the core distribution area in Western Europe and occur at their climatic limits. This study aimed to analyze floristic patterns of heather communities in NW Italy in order to provide detailed recommendations for local conservation needs. Data on plant species composition (phytosociological relevés) and abiotic (environmental and geographical) factors were jointly analyzed using multivariate statistical analyses, to provide a quantitative and statistical interpretation of variation among heathland communities. We show that diversity in species composition was associated with variation in abiotic factors, and we sorted an initial list of “typical species” of the heather’s habitat among indicator species. Several subtypes of heathlands were also recognized and related to habitats “élémentaires”, which require specific conservation measures to preserve their floristic diversity. Finally, we proposed a revised syntaxonomy of heathlands for NW Italy.
:: ANONYMOUS Erratum Paru dans Botany Letters, 2017, 164 (4), pp. 445-445. Anglais