The classification of the legume family proposed here addresses the long‐known non‐monophyly of the traditionally recognised subfamily Caesalpinioideae, by recognising six robustly supported monophyletic subfamilies. This new classification uses as its framework the most comprehensive phylogenetic analyses of legumes to date, based on plastid matK gene sequences, and including near‐complete sampling of genera (698 of the currently recognised 765 genera) and ca. 20% (3696) of known species. The matK gene region has been the most widely sequenced across the legumes, and in most legume lineages, this gene region is sufficiently variable to yield well‐supported clades. This analysis resolves the same major clades as in other phylogenies of whole plastid and nuclear gene sets (with much sparser taxon sampling). Our analysis improves upon previous studies that have used large phylogenies of the Leguminosae for addressing evolutionary questions, because it maximises generic sampling and provides a phylogenetic tree that is based on a fully curated set of sequences that are vouchered and taxonomically validated. The phylogenetic trees obtained and the underlying data are available to browse and download, facilitating subsequent analyses that require evolutionary trees. Here we propose a new community‐endorsed classification of the family that reflects the phylogenetic structure that is consistently resolved and recognises six subfamilies in Leguminosae: a recircumscribed Caesalpinioideae DC., Cercidoideae Legume Phylogeny Working Group (stat. nov.), Detarioideae Burmeist., Dialioideae Legume Phylogeny Working Group (stat. nov.), Duparquetioideae Legume Phylogeny Working Group (stat. nov.), and Papilionoideae DC. The traditionally recognised subfamily Mimosoideae is a distinct clade nested within the recircumscribed Caesalpinioideae and is referred to informally as the mimosoid clade pending a forthcoming formal tribal and/or clade‐based classification of the new Caesalpinioideae. We provide a key for subfamily identification, descriptions with diagnostic charactertistics for the subfamilies, figures illustrating their floral and fruit diversity, and lists of genera by subfamily. This new classification of Leguminosae represents a consensus view of the international legume systematics community; it invokes both compromise and practicality of use.

Petal structure and the distribution of pigments in petals were studied in relation to the functional anatomy of petals and the ways in which petals absorb and reflect light. We examined 201 species from 60 angiosperm families. Anthocyanins, betalains and ultraviolet-absorbing flavonoids were normally confined to the epidermal cells, occurring in solution in the vacuole; carotenoids were found in the epidermis and in smaller quantities in the mesophyll, normally in chromoplasts. In a few species, mainly blue-flowered members of the Boraginaceae and Liliaceae-Scilleae, anthocyanins were confined to the mesophyll.Six basic kinds of petal epidermis anatomy were found, sometimes in combination; papillate (1 12 species) and multiple-papillate (13 species), in which the conical-papillate form of the cells traps incident light and scatters emergent light, with surface striations aiding these functions in many cases; reversed-papillate (4 species), multiple reversed-papillate (29 species), lenticular (32 species) and flat ( I 1 species), all with surfacestriations in some cases. Light is usually reflected from petals mainly by an aerenchymatous unpigmented reflective mesophyll; in certain species this is replaced by a reflective layer of starch grains in the upper mesophyll.

Rhizobial diversity and host preferences were assessed in 65 native Fynbos legumes of the papilionoid legume tribes Astragaleae, Crotalarieae, Genisteae, Indigofereae, Millettieae, Phaseoleae, Podalyrieae, Psoraleeae and Sesbanieae. Sequence analyses of chromosomal 16S rRNA, recA, atpD and symbiosis-related nodA, nifH genes in parallel with immunogold labelling assays identified the symbionts as alpha- (Azorhizobium, Bradyrhizobium, Ensifer, Mesorhizobium and Rhizobium) and beta-rhizobial (Burkholderia) lineages with the majority placed in the genera Mesorhizobium and Burkholderia showing a wide range of host interactions. Despite a degree of symbiotic promiscuity in the tribes Crotalarieae and Indigofereae nodulating with both alpha- and beta-rhizobia, Mesorhizobium symbionts appeared to exhibit a general host preference for the tribe Psoraleeae, whereas Burkholderia prevailed in the Podalyrieae. Although host genotype was the main factor determining rhizobial diversity, ecological factors such as soil acidity and site elevation were positively correlated with genetic variation within Mesorhizobium and Burkholderia, respectively, indicating an interplay of host and environmental factors on the distribution of Fynbos rhizobia.

Rhizobia of the genus Burkholderia have large-scale distribution ranges and are usually associated with South African papilionoid and South American mimosoid legumes, yet little is known about their genetic structuring at either local or global geographic scales. To understand variation at different spatial scales, from individual legumes in the fynbos (South Africa) to a global context, we analyzed chromosomal (16S rRNA, recA) and symbiosis (nifH, nodA, nodC) gene sequences. We showed that the global diversity of nodulation genes is generally grouped according to the South African papilionoid or South American mimosoid subfamilies, whereas chromosomal sequence data were unrelated to biogeography. While nodulation genes are structured on a continental scale, a geographic or host-specific distribution pattern was not detected in the fynbos region. In host range experiments, symbiotic promiscuity of Burkholderia tuberum STM678 T and B. phymatum STM815 T was discovered in selected fynbos species. Finally, a greenhouse experiment was undertaken to assess the ability of mimosoid (Mimosa pudica) and papilionoid (Dipogon lignosus, Indigofera filifolia, Macroptilium atropurpureum, and Podalyria calyptrata) species to nodulate in South African (fynbos) and Malawian (savanna) soils. While the Burkholderia-philous fynbos legumes (D. lignosus, I. filifolia, and P. calyptrata) nodulated only in their native soils, the invasive neotropical species M. pudica did not develop nodules in the African soils. The fynbos soil, notably rich in Burkholderia, seems to retain nodulation genes compatible with the local papilionoid legume flora but is incapable of nodulating mimosoid legumes that have their center of diversity in South America. IMPORTANCEThis study is the most comprehensive phylogenetic assessment of root-nodulating Burkholderia and investigated biogeographic and host-related patterns of the legume-rhizobial symbiosis in the South African fynbos biome, as well as at global scales, including native species from the South American Caatinga and Cerrado biomes. While a global investigation of the rhizobial diversity revealed distinct nodulation and nitrogen fixation genes among South African and South American legumes, regionally distributed species in the Cape region were unrelated to geographic and host factors.

Background: The loss of biodiversity in Nigeria is escalating alarmingly. However, there is generally a paucity of information as to what taxa are endangered because of a dearth of functioning conservation agencies in Nigeria.Objectives: The aim of this research is to record the endangered medicinal and other economic plant species in the Sudan Savanna vegetation in Katsina and to provide an assessment of the various threats faced by these plants.Method: Medicinal plants were identified through oral interviews with traditional medical practitioners within the study area. Conservation statuses were assessed using a bespoke data collection and assessment form; the data were then evaluated using the International Union for the Conservation of Nature Red List categories and criteria.Results: A total of 169 species belonging to 62 families were recorded. Of these, 43 taxa were reported to be used for ethnomedicinal practices. It was found that more than half (108) of the 169 species were threatened with extinction and one taxon (Xeroderris stuhlmannii [Taub.] Mendonca Sousa) qualifies as being Extinct locally. Threats recorded include overexploitation (24%), agriculture (15%), deforestation and desertification (12% each), invasive plants (11%), urban residential development (7%) and erosion (6%).Conclusion: Most of the plants are already under threat and require urgent conservation measures. The data point to the critical need for further research into conservation strategies and a more sustainable use of threatened plants. We recommend that the Nigerian government should establish a national Red List agency and ensure effective protected area management and community-based natural resources management.