Psoraleeae consist of c. 228 species in ten genera, distributed worldwide but mostly in the temperate biome. Here, we reconstruct the phylogenetic history of Psoraleeae using eight molecular markers (rpl32-trnL, trnQ-rps16, trnS-trnG, matK, rbcLa, rpoB-trnC, trnL-trnF and ITS) to test the monophyly and previous hypotheses on generic relationships and to reconstruct the biogeographical history (distribution pattern, potential ancestral area and biome). The monophyly of Psoraleeae is supported. The African Otholobium and Psoralea form a strongly supported clade that is sister to the rest of Psoraleeae. However, Otholobium is not monophyletic; the American taxa of the genus are resolved as closer to Bituminaria, whereas Psoralea is a clade derived from within African Otholobium. South African Otholobium is subsumed into Psoralea, the latter having priority, with a synopsis of species level nomenclature provided here. An expanded sampling of Cullen reveals three clades comprising Mediterranean (Cullen americanum), African (Cullen obtusifolium and Cullen biflorum) and Eurasian (Cullen corylifolium and Cullen drupaceum) taxa, whereas Australian Cullen are a derived clade (BS = 95%, PP = 1.00). Biogeographic reconstructions show that Psoraleeae probably originated in the Mediterranean south biome of Africa in the Late Miocene, c. 8.2 Mya, and then dispersed into the succulent biome of the Americas, Mediterranean north biome, temperate grasslands of Africa and Australia to the temperate forest of Eurasia. Climate changes in the Late Miocene, changes induced by ocean currents during the Quaternary and environmental heterogeneity are proposed as the major drivers of speciation in Psoraleeae.

Over 760 legume species occur in the ecologically-heterogeneous Core Cape Subregion (CCR) of South Africa. This study tested whether the main symbionts of CCR legumes (Burkholderia and Mesorhizobium) are phylogenetically structured by altitude, pH and soil types. Rhizobial strains were isolated from field nodules of diverse CCR legumes and sequenced for 16S ribosomic RNA (rRNA), recombinase A (recA) and N-acyltransferase (nodA). Phylogenetic analyses were performed using Bayesian and maximum likelihood techniques. Phylogenetic signals were determined using the D statistic for soil types and Pagel’s λ for altitude and pH. Phylogenetic relationships between symbionts of the narrowly-distributed Indigofera superba and those of some widespread CCR legumes were also determined. Results showed that Burkholderia is restricted to acidic soils, while Mesorhizobium occurs in both acidic and alkaline soils. Both genera showed significant phylogenetic clustering for pH and most soil types, but not for altitude. Therefore, pH and soil types influence the distribution of Burkholderia and Mesorhizobium in the CCR. All strains of Indigofera superba were identified as Burkholderia, and they were nested within various clades containing strains from outside its distribution range. It is, therefore, hypothesized that I. superba does not exhibit rhizobial specificity at the intragenic level. Implications for CCR legume distributions are discussed.

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.

Indigofera L. is the most diverse genus in the tribe Indigofereae and the third largest genus in the Fabaceae with over 750 species distributed in most tropical to temperate areas of the world. The centre of diversity of the genus lies on the African continent, accounting for over two-thirds of its global diversity. Diversification of Indigofera’s four main clades began in the Early Miocene, with the Tethyan and Cape Clades having slightly older crown ages than the Pantropical and Paleotropical Clades. Using biogeographical models under a newly assembled, more comprehensively-sampled ITS phylogeny, we confirmed that the tribe Indigofereae originated in the Africa-Madagascar centre, with the genus Indigofera resolving with a mainland African origin c. 38 Mya. Long-distance dispersals were rare, but did occur from Africa to South America and Africa to Australia during the late Miocene. Multiple dispersals from Africa into Asia took place via the arid north-east African and Arabian corridors during the same period. At least four Indigofera dispersals to Madagascar took place during the Miocene. The Cape Clade is a narrowly endemic lineage, mostly restricted to the Greater Cape Floristic Region (GCFR) of southwestern South Africa, while the Tethyan, Pantropical and Paleotropical Clades are more widely dispersed across multiple continents. Both the Cape and Tethyan Clades display strong signals for arid origins in the southern Namib and Richtersveld regions of Southwestern Africa. This study emphasizes the importance of the global Succulent biome in shaping biogeographical patterns of Indigofera globally, particularly in terms of biome conservatism and how it created corridors facilitating trans-continental dispersal.

A new species of Psoralea is described. Psoralea margaretiflora C.H. Stirton & V.R. Clark is endemic to the Sneeuberg Centre of Floristic Endemism, Eastern

Background and aims – Following detailed phylogenetic and biogeographic studies of the tribe Psoraleeae, the genus Psoralea L. was shown to have been derived out of Otholobium C.H.Stirt. As Psoralea has nomenclatural priority, Otholobium has been subsumed into Psoralea, whereby two broad subgeneric groups are aligned with the previous descriptions of the separate genera, but some problems of placement of a few species remain unresolved. Work is ongoing to study and describe the nearly 20 undescribed species that will have to be considered before sectional groups can be established. In this paper we describe ten new species, including several putative taxa already recognized in regional floras, based on historic specimens and more recent field collections. Material and methods – Standard practices of herbarium and field taxonomy have been applied to study herbarium material available at B, BLFU, BM, BOL, BR, E, GRA, J, JRAU, K, KEI, L, LE, LINN, M, MO, NBG, NH, NU, NY, OXF, P, PRA, PRC, PRE, PRU, S, SAM, SCHG, SRGH, TCD, Z, ZT, and US. Additional material was provided from fieldwork by the authors and collaborators. Key results – Ten new species of Psoralea from southern Africa are described: Psoralea crista C.H.Stirt. & Muasya, P. fulva C.H.Stirt. & Muasya, P. luteovirens C.H.Stirt. & Muasya, P. nubicola C.H.Stirt. & Muasya, P. oreopola C.H.Stirt., P. pallescens C.H.Stirt. & Muasya, P. papillosa C.H.Stirt. & Muasya, P. prompta C.H.Stirt. & Muasya, P. schutteae C.H.Stirt. & Muasya, and P. vlokii C.H.Stirt. & Muasya. Conclusion – The newly described species, all restricted to South Africa, increases the number of Psoralea species to 129. These species arise from expanded fieldwork into previously under-collected areas, as well as from better refinement in species delimitations in the leafless ‘aphylla’ and pinnately-leaved species complexes.