Royal Botanic Gardens, Kew
  • Richmond, United Kingdom
Recent publications
This study was conducted in the context of a taxonomic treatment for Myrcia species occurring in the Brazilian state of Rio de Janeiro. While revising current synonyms of endemic species of Myrcia sect. Gomidesia, we found consistent morphological separation between Myrcia gestasiana and Myrcia dolichopetala, presently treated as synonyms and detached here. Individuals co-occurring with M. dolichopetala are here recognized and described as a new species, Myrcia macrobracteosa, the specific epithet being allusive of its unusually showy, persistent and accrescent bracts and bracteoles. A taxonomic treatment is provided for each species based on herbarium collections and field data, and their diagnostic characters are contrasted in a comparative table. Morphological plates of fresh and dry material are also provided with notes on taxonomy and distribution , including a map of occurrence records. The three taxa occur in urban forest remnants under extreme threat in the Rio de Janeiro Metropolitan Region. In this context, preliminary conservation assessments are also provided for each species based on occurrence data from herbaria and field information.
Environmental exposure to cold is increasingly being associated with changes in metabolism. We developed and tested the hypothesis that exposure to cold drives systemic effects in lipid metabolism. Specifically, (i) that energy storage and provision adapts to the cold by altering triglyceride distribution and (ii) that membranes adapt to cold conditions by becoming more unsaturated. These hypotheses were designed to identify the underlying mechanisms that govern the response of mammalian systems to cold. To test these hypotheses, we used a metabolic network analysis. An established model of cold exposure was used, from which lipidomics data that represents the system was collected. The network analysis showed that triglyceride metabolism is altered on exposure to cold, with several smaller effects that are not straightforward, such as changes to the abundance and distribution of odd chain fatty acids. The range and profile of phosphatidylcholine and phosphatidylinositol were modified, but there was little change in phosphatidylethanolamine or sphingomyelin. These results support the hypothesis, and show that exposure to cold is a system-wide phenomenon that requires or drives changes across a range of metabolic pathways.
Serpentine ecosystems are characterised by multiple environmental stressors: high levels of trace metals such as nickel (Ni), low availability of macronutrients and low water retention. These harsh environmental conditions exert a strong selective force on the vegetation, but their effect on community assembly processes and the functional trait composition remains unknown. In 26 plots on four serpentine sites on Lesbos Island (Greece), we measured six leaf functional traits related to resource acquisition and stress resistance on the 20 most abundant plant species. We quantified the proportion of variance explained by inter‐ and intraspecific trait differences and tested if individual species showed changes in trait values explained by soil Ni content. We investigated the adaptive value and the community level changes for each trait along the natural soil Ni gradient using a mixed model approach and functional diversity analyses. We tested the role of the abundant serpentine endemic and Ni‐hyperaccumulating species Odontarrhena lesbiaca in driving these patterns. Intraspecific variation explained by soil Ni content is smaller than 4%, and most of the variance is explained by interspecific differences in trait values. Most species do not show significant changes in trait values in response to soil Ni. At the community level, low specific leaf areas, small and thick leaves are selected on high Ni soils. Functional diversity analyses suggest a shift towards a stress tolerance syndrome (thick and small leaves with low SLA values) and an increase in functional diversity on Ni‐rich soils. However, these patterns are driven by the increasing abundance of O. lesbiaca. The endemic Ni hyperaccumulator has a stress tolerance strategy with small thick leaves and low SLA, while the community of broadly distributed species show an increase in trait values related to dominance and fast growth. Synthesis. Intraspecific variation in leaf trait responds little to soil metal toxicity. Endemic species harbour unique trait values compared to species with broad distribution which should justify their conservation as a priority.
The Vitex trifolia complex is a well-circumscribed and monophyletic group. However, the species of the group are morphologically very similar and therefore, taxonomic boundaries within the group are uncertain. In addition, these medicinal plants have been cultivated and naturalised in many areas across the world and therefore the irnatural geographical distributions are not well known. A taxonomic account of the complexis presented in which nine species are recognized: Vitex agnus-castus , V. benthamiana , V. bicolor , V. negundo, V. pseudonegundo, V. rotundifolia and V. trifolia ; a new species, Vitex collium Sengun, is described from frost prone regions of northern and Central China and an obscure name, V . hybrida Moldenke, is recognised for the Indian specimens previously recognized as V. negundo . In addition, Agnus-castus , V. cannabifolia , V. chinensis , V. latifolia , V. negundo f. alba , V. negundo f. intermedia , V . negundo f. laxipaniculata , V. rotundifolia and V. trifolia var . acutifolia are lectotypified, and V. leucoxylon Blanco has been neotypified. Also, many names have been placed in synonomy for the first time.
Stachytarpheta eimeariae and S. praetermissa are newly described and included in the Radlkoferiana group due to their flowers with 2-toothed calyces and bright red to pinkish corollas. The first is a new species differentiated from the typical concept of S. ganevii by a set of mainly vegetative characteristics, while the second is a new status and name for S. radlkoferiana var. lanata due to a set of characteristics associated with the leaves and bracts. The two new species grow in campo rupestre vegetation, with S. eimeariae found in the Abaíra municipality and S. praetermissa in Mucugê of Bahia, Brazil. They should be considered threatened, which reinforces the need for activities to promote the conservation of campo rupestre in the Chapada Diamantina. With these additions, the Radlkoferiana group now includes 11 species; an identification key and a distribution map are provided, alongside illustrations and taxonomic notes.
Adesmia is the most species-rich genus in the informal Adesmia clade and temperate South America Leguminosae. The pollen morphology, ultrasculpture, and ultrastructure of 25 species of Adesmia were studied using light, scanning, and electron transmission microscopy to explore micromorphological data informative to the taxonomy of the genus. Additionally, a principal component analysis was performed to elucidate patterns of quantitative data variation among species concerning the most recent molecular data. We provide novel data about the genus, a comprehensive description of the pollen grains and sexine ultrasculpture, and descriptions of the exine ultrastructure. Furthermore, we suggest delimiting two pollen types based on the size of equatorial and polar axis dimensions to help in future palynotaxonomic studies and character optimisation focusing on pollen traits.
Background and aims The host specificity of a parasite underpins its ecology, distribution, invasive potential and adaptability, yet for most parasitic plants host ranges are poorly understood. We examine host-parasite relationships across lineages to infer how host specificity may have influenced the evolution of parasitism in plants. Methods Host preference data for all plant holoparasite species were manually collected from literature and herbarium specimens, then analysed to investigate and visualise host diversity and specificity. Key Results We reveal a disproportionality in host preference across host lineages: the Asteraceae contains 10% of angiosperm diversity but is infected by 31% of parasite species; meanwhile Monocots comprise 23% but are infected by just 3.2%. Furthermore, we observe striking convergence in host preference: Asteraceae, Euphorbiaceae and Fabaceae are infected by six, five and four independent parasite lineages, respectively. We also demonstrate considerable variation in the degree of host specificity among closely related parasite species; a result that does not reflect the expectation of holoparasites – especially endoparasites - as host specialists. Conclusions The marked pattern of convergence in preference across disparate lineages points to a common pathway in the evolution of parasitism of eudicots in preference to monocots, which may have in turn have been driven by a divergence in host root and vascular architecture. The unexpected variation in host specificity among closely related species suggests that even apparent generalists may comprise cryptic host-specific taxa. This highlights the value of host preference as an additional consideration in parasitic plant taxonomy. Together, our data point to a complex interplay between ecological and physiological factors driving the evolution of host-parasite interactions. Moreover, they emphasize how little is known about the ecology of most holoparasitic plants, a group of organisms that are especially vulnerable at a time of unprecedented biodiversity loss and extinction.
During the preparation of Clusiaceae for the Manual de Plantas de Costa Rica , several new species of Clusia L. were identified but left with lettered informal names. Here, we formally describe two of those. Clusia dotana Hammel can be distinguished most assuredly from morphologically related species by its pistillate flowers with 24 – 26 (– 42) staminodes and the unusual large mass of yellow arillate tissue covering the seeds. Clusia osaensis Hammel is similar to C. dotana but distinct by having relatively longer inflorescences (5 – 15 cm vs 4.5 cm), pistillate flowers with 16 staminodes, and seeds covered in an orange aril. These two new species are known from a limited number of localities and are endemic to mountain and lowland forests on the Pacific slopes in central and southern Costa Rica.
The tropical Andes region harbors areas that are highly significant for biodiversity at both global and local scales. However, despite the severe conservation threats that this region has to confront, conservation initiatives are limited, by funding and because of the need for more information to decide which areas are priorities for conservation. Identifying Important Plant Areas (IPAs) offers a valuable methodology for establishing conservation priorities, a particularly complex task in a mega-biodiverse region such as the northern Andean tropics. Due to its iconic recognition and conservation value, this study focused on the Espeletiinae subtribe (Asteraceae) as a model group; hence, the distribution data for 138 species was compiled from 5560 georeferenced records. Using the IPA methodology, we divided the study area, this is, the distribution area of the subtribe in the Andean tropics, into 220 Units of Analysis (UA) represented by 10 × 10 km plots. Refined species’ distribution areas, incorporating richness, threatened species, and ecosystem-based richness distributions, were analyzed using newly generated maps to evaluate the conservation value of each UA. Our analysis identified 176 UAs with some level of relevance using sub-criterion cA1 (with 59 species) and 51 UAs using sub-criterion cB (with 76 species). Integrating both criteria, we classified 11 UAs as high-priority, 62 as medium-priority, and 147 as low-priority, highlighting the IPAs that require focused conservation efforts. Two identified high-priority IPAs are located in Venezuela and nine in Colombia, predominantly associated with the Eastern Cordillera. These areas concentrate between 7 and 12 species. They are mainly linked to the páramo complexes of Colombia and the Sierra Nevada in Venezuela, primarily within Cool Temperate Moist Grassland ecosystems on mountains. Our results provide a spatial planning procedure and analytical tool for decision-makers to guide conservation management and actions across northern Andes.
Background and Aims Herbaria are the most important source of information for plant taxonomic work. Resources and technologies available today, such as digitised collections and herbarium DNA sequencing, can help accelerate taxonomic decisions in challenging plant groups. Here we employ an integrative methodology relying exclusively on herbarium specimens to investigate species boundaries in the Neotropical Myrcia neoobscura complex (Myrtaceae). Methods We collected morphometric data from high-resolution images of herbarium sheets and analysed it using hierarchical clustering. We posteriorly tested the obtained morpho-groups with phylogenomics using the Angiosperms353 probe kit. We also gathered phenological and geographic information from specimen labels and built phenological histograms and ecological niche models to investigate ecological differences amongst taxa. Key Results Current circumscriptions of Myrcia arenaria, Myrcia neoglabra and Myrcia neoregeliana are confirmed in this study. Conversely, the four pieces of evidence together support Calyptranthes langsdorffii var. grandiflora, Marlierea regeliana var. parviflora and Marlierea warmingiana as separate from Myrcia marliereana, Myrcia neoriedeliana and Myrcia neoobscura, respectively, contrary to arrangements proposed by previous authors. Integrated analyses also support separation between Myrcia excoriata and two similar, undescribed taxa. Conclusions Our data reveal the need for major changes in the systematics of the group, with recognition of 12 species. The successful delivery of our study aims was possible due to obtaining robust, high-quality data from museum specimens. We emphasise the importance of maintaining botanical collections physically and digitally available for taxonomic work and advocate their use to accelerate holistic taxonomic solutions of tropical species complexes. This is urgent, given the paucity of funds for fieldwork and unprecedented rates of habitat loss in the tropics.
Climate change models predict temperature increases, which may affect germination, an important stage in the recruitment of individuals in agroecosystems. Therefore, it is crucial to conduct research on how temperature will impact the germination of multipurpose native species. Leucaena diversifolia (Schltdl.) Benth. is native to America and is commonly cultivated around the world due to having a high protein content in seeds, and their trees are used in agrosilvopastoral systems because they fix nitrogen and provide shade and cattle feed. However, climate change affects the critical phases of its life cycle and influences its growth, reproduction, phenology, and distribution. To assess the germination performance of Leucaena diversifolia under different temperatures throughout thermal times, we estimated germination variables and determined cardinal temperatures and thermal time; we also analysed germination and potential distribution under two climate change scenarios. We found significant variations in seed germination (78–98%) and differences in cardinal temperatures (Tb = 5.17 and 7.6 °C, To = 29.42 and 29.54 °C, and Tc = 39.45 and 39.76 °C). On the other hand, the sub-optimal and supra-optimal temperature values showed little differences: 51.34 and 55.57 °Cd. The models used showed variations in germination time for the analysed scenarios and the potential distribution. We confirm that the populations and distribution of L. diversifolia will be altered due to climate changes, but the species retains the ability to germinate under warmer conditions.
We emphasise the urgent need to conserve the Ebo forest (Littoral Region, Cameroon), which holds 10 strict endemic plant species and 15 near endemics for a total of 25, a very high number far exceeding the threshold for its recent status as an Important Plant Area (IPA). We describe a further strict endemic species from the Ebo Forest, Memecylon ebo sp. nov. (Melastomataceae-Olisbeoideae), placed in sect. Afzeliana due to its ellipsoid, blue-green fruits. The yellow petals and jade green anther-connectives of M. ebo are unique in the genus Memecylon, which has >400 species ranging overall from Africa to the western Pacific. Memecylon ebo is assessed as Critically Endangered [CR], using the 2012 IUCN standard, due to its small range size and the extremely high and ongoing threats of logging at Ebo and also due to subsequent threats of potential oil palm plantation and mining projects. With the addition of Memecylon ebo, the tally of Critically Endangered plant species recorded from Ebo forest is now the highest of any IPA in Cameroon, equalling that of Ngovayang with 24 CR species.
Seed storage life in tropical areas is shortened by high humidity and temperature and the general inaccessibility to dehumidifying and refrigeration systems, resulting in rapid decreases in seed viability in storage as well as a high incidence of fungal and insect infestations. The dry chain, based on rapid and deep drying of seeds after harvest followed by packaging in moisture-proof containers, has been proposed as an effective method to maintain seed quality during medium-term storage in humid climates, even without refrigeration. In addition, seed drying with zeolite drying beads can be more effective and economical than sun or heated-air drying under these warm, humid conditions. In this paper, we review recent published literature regarding the dry chain, considering different crop species, storage environments and seed traits. In addition, we provide new original data on the application of dry chain methods and their implementation at larger scales in South Asia, Latin America and Pacific Island Countries. The clear conclusion is that the combination of reusable drying beads and waterproof storage containers enables the implementation of the dry chain in tropical climates, enhancing seed viability and quality in storage of many crop species. The dry chain approach can therefore significantly enhance seed security for farmers in many tropical countries. Finally, we propose actions and strategies that could guide further scaling-up implementation of this technology.
The genus Aerangis Schltr. (Orchidaceae, subfamily Epidendroideae, tribe Vandeae, subtribe Angraecinae) in Madagascar and adjacent archipelagos is revised. Twenty-seven species have been recorded from the region, all of them endemic. Twenty of these are endemic to Madagascar, three to the Comoros only, three to the Comoros and Madagascar and one to Madagascar and Réunion. A third of all Aerangis in the area were assessed to be immediately endangered with 15% Critically Endangered (CR) and 18.5% Endangered (EN). 37% are considered Vulnerable (VU), 15% Near Threatened (NT) and 11% are of Least Concern (LC). Section Microterangis (Schltr.) Hermans is newly established. All the species are described and their typification, history, identification, pollination, distribution and habitat are discussed. The nomenclature and identity of Aerangis citrata (Thouars) Schltr., A. cryptodon (Rchb.f.) Schltr., A. ellisii (B.S.Williams) Schltr., A. hildebrandtii (Rchb.f.) P.J.Cribb & Carlsward, A. ikopana Schltr., A. modesta (Hook.f.) Schltr., A. monantha Schltr., A. polyura (Sander ex Mast.) Hermans and A. rostellaris (Rchb.f.) H.Perrier, are reassessed. Conservation assessments, illustrations and distribution maps are included for all the species. A checklist of the sections, species and a key to their identification are provided. Aerangis bursiculata Hermans is described from the Comoros for the first time.
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368 members
Ilia Leitch
  • Trait Diversity and Function
Rinku Desai
  • Herbarium
MK Langat
  • Natural Capital and Plant Health
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