Astragalus centralis: The Tamditau Milkvetch evaluated as Critically Endangered.

Milkvetches, Astragalus spp., are leguminous herbs of or shrubs, predominantly found in arid or semi-arid climates around the Northern Hemisphere. They are a large group of Plants, with 3082 species recognised in 2025, this is largely because many species are highly endemic (i.e. have very limited ranges). Such limited ranges can make species extremely vulnerable to extinction, though to date only 149 species of Astragalus have been formerly assessed to determine their status under the terms of the International Union for Conservation of Nature's Red List of Threatened Species, with 36% of these being determined to be threatened, and one, the Tallante's Milkvetch, Astragalus nitidiflorus, has been found to be extinct in the wild.

Thirty two species of Astragalus have been recorded in Uzbekistan, more than any other genus in the country. Most of these are found within the low mountain ranges of the Kyzylkum Desert, a notable centre of Plant endemism covering parts of Uzbekistan, Kazakhstan, and Turkmenistan. Within this desert a series of low mountain ranges (typically lower than 1000 m) form a western extension of the Central Asian Mountain Belt, creating a range of distinctive micro-habitats. promoting Plant endemism. Of the forty two species of Astragalus known from this region, six are thought to be entirely endemic. 

In a paper published in the journal Orynx on 18 February 2026, Bekhruz Khabibullaev, Khabibullo Shomurodov, and Natalya Beshko of the Institute of Botany of the Academy of Sciences of the Republic of Uzbekistan, and Giuseppe Fenu of the Department of Life and Environmental Sciences at the University of Cagliari, formally assess the conservation status of Astragalus centralis, referred to here as the Tamditau Milkvetch, an endemic species from the Kyzylkum Desert of Uzbekistan. 

The Tamditau Milkvetch is a perennial herbaceous Plant reaching about 15 cm in height, with stems covered in white hairs, paired leaves, and dense inflorescences of yellow flowers. It was formerly thought to be present in the Tamditau, Kuldzhuktau, and Auminzatau mountain ranges within the Kyzylkum Desert. However, a previous study, published in 2016, established that the populations in the Kuldzhuktau and Auminzatau mountains were in fact a separate species, which was described as Astragalus kuldzhuktauense. 

As a result of this, the known occurence of Astragalus centralis shrank to a single population in the Tamditau Mountains, prompting monitoring and censuses of the species in 2016-17, 2018-19, and 2023-24, each time assessing the number of Plants present at the peak of the flowering season.

The Tamditau Milkvetch grows on northern slopes in the Tamditau Mountains, in crevices between large boulders in gravelly and rocky limestone soils. All known members of the species are found within an area of 60 000 m². During the 2016-17 season, about 1000 Plants were recorded, but in 2018-19 this had fallen to about 600 individuals, within an increased proportion of older Plants (80% against 50% in 2016-17. In 2023-24 only 491 Plants were recorded, with 90% of these being mature.

The mountains of the Kyzylkum Desert, Uzbekistan, showing the distribution of Astragalus centralis on the northern slope of the Tamditau (Aktau) mountains. Khabibullaev et al. (2026).

The species appears to be facing a number of immediate threats. Limestone is extracted in the region, and new excavation trenches are both present and increasing in number within the range of the Tamditau Milkvetch. The population is also located close to a settlement which primarily derives its income from livestock herding, with the area where the species grows being used as a year-round pasture. Climate change appears to be making the area more arid, and Insects have been observed to consume more of the species seeds in dryer years. This drying climate is also associated with more frequent and intense spring flash floods, which can destroy younger Plants with less well established root systems. The species is also vulnerable to short-term cold anticyclones, which occur in the area every 5-6 years.

Characteristic habitat of Astragalus centralis, endemic to the Tamditau (Aktau) mountains. Khabibullo Shomurodov in Khabibullaev et al. (2026).

Based upon this, Khabibullaev et al. suggest that the Tamditau Milkvetch is becoming unable to sustain its only population, due to a low and decreasing survival rate for young Plants. For this reason they recommend that the species be classified as Critically Endangered under the terms of the International Union for Conservation of Nature's Red List of Threatened Species. 

The Tamditau Milkvetch in its habitat. Khabibullo Shomurodov in Khabibullaev et al. (2026).

Based upon this, Khabibullaev et al. recommend a series of steps to be taken in order to protect the future of the Tamditau Milkvetch. 

Firstly, the species habitat should be designated a protected area. This would not just protect this species, but also other species found in the area which have been identified as at risk, including the Kyzylkum Giant Fennel, Ferula kyzylkumica, the Aktavi Stickseed, Lappula aktaviensis, The Kyzylkum Peppergrass, Lepidium subcordatum, the Hairy Catchfly, Silene tomentella, and the Aktau Needlegrass, Stipa aktauensis. They further recommend that the Tamditau Mountains should be considered to be a significant national ecosystem, and assessed for potential inclusion on the nternational Union for Conservation of Nature's Red List of Ecosystems.

Detail of the inflorescence of the Tamditau Milkvetch, Astragalus centralis. Khabibullo Shomurodov in Khabibullaev et al. (2026).

Secondly, they recommend that an inventory of pasture resources in the region is carried out, in order to determine the sustainable grazing capacity of the area, and develop a better plan for livestock management.

Thirdly, they suggest a translocation strategy for the species, moving individual Plants to other areas identified as suitable for its survival.

Fourthly, they suggest that a cultivated population be established at the Kyzylkum Desert Experimental Station, and seeds of the species be gathered and placed in an appropriate seed bank.

Finally, they suggest that the species be included on the International Union for Conservation of Nature's Red List of Threatened Species, and an awareness campaign for the species be used to promote its conservation.

See also...

The distribution and conservation status of Wild Rooibos Plants, Aspalathus linearis.

Rooibos Tea is a traditional herbal drink from South Africa, not marketed internationally. It is made from the leaves of the Rooibos Plant, Aspalathus  linearis, a type of Cape Gorse which grows wild in dry areas of the northwestern part of the Fynbos Biome, part of the wider Cape Floristic Region. Although traditionally harvested from wild plants, the modern Rooibos industry is built around large scale cultivation of the plant, with only a tiny amount of the total crop harvested from the wild.

Thus the Rooibos Plant is considered to be an economically significant plant in South Africa. Although the commercial harvest is tied to agricultural production, this the wild population preserves a  wider genetic heritage, which may become important should the commercial crop be threatened by disease or climate change. However, while quite a lot of research has been published into Rooibos, most of this relates to commercial cultivation, leaving us with little understanding of the ecology, distribution, or conservation status of the wild plants.

In a paper published in the South African Journal of Science on 26 November 2025, Tineke Kraaij of the Natural Resource Science and Management Cluster at Nelson Mandela University, Vernon Visser of the Centre for Statistics in Ecology, Environment and Conservation, and National Institute for Theoretical and Computational Sciences, at the University of Cape Town, and Gerhard Pretorius of NaturaLibra Environmental Services, present the results of a study which looked at the current distribution, potential distribution, population size, and threats to the population size of Wild Rooibos Plants in South Africa, with a view to creating a baseline against which future monitoring of the species could be measured.

Rooiboss is grows in areas with cold wet winters and hot dry summers, with annual rainfall levels of between 300 and 600 mm, and at elevations of between 450 and 900 m. It is found as far north as Vanrhynsdorp and as far south as Betty's Bay and the Cape Peninsula, and anecdotally grows as far east as Riviersonderend and Bredasdorp, 

Wild Rooibos is an extremely variable species (potentially being a species cluster - a group of closely related species difficult to tell apart - rather than a true species), and can be difficult to differentiate from closely related African Gorse species such as Golden Tea, Aspalathus pendula, or Lebeck's Roiibos, Aspalathus lebeckioides. Wild Rooibos also has several different ecotypes, strains of the plant with different morphologies and environmental preferences, further complicating efforts to understand the distribution of the species.

The ecotypes of Wild Rooibos vary in habit, fire-survival strategy, vegetative and reproductive morphology, biochemistry, and genetics. They can be loosely grouped into four main forms, 'Erect' or 'Upright', 'Prostrate', 'Bush' or 'Shrub', and 'Tree' (although 'Tree' is sometimes regarded as a variant on the 'Erect' or 'Upright' form). A 'Salignus' form is also sometimes recognised, this having a Willow-like growth with multiple lanky stems reaching 2-3 m tall and a sparse canopy. The Prostrate and Shrub forms are wider than they are tall, and tend to have many branches close to the ground, and can resprout after a fire. The Erect, Tree, and Saliginus forms are tall, and only regrow from seeds. In addition to these, there is the commercially grown 'Nortier' form, a cultivar bred from the Erect form, which is tall like its parent, but also has the dense branching of the Bush form, giving it a large harvestable biomass. 

Exemplary images of the different ecotypes or growth forms of Wild Rooibos, Aspalathus linearis, namely the (a) Bush or Shrub form, (b) Prostrate form, (c) Erect (including Upright or Tree) form, and (d) Salignus form. Kraaij et al. (2025).

These different ecotypes have different distributions. The Bush, Prostrate and Tree types occur towards the northern part of the species’ range, and the Prostrate, Erect and Salignus types toward the south. The Erect and Salignus types favour higher elevations, above 400-600 m. The Bush ecotype is predominant in areas with low rainfall (less than 200 mm per year), while the Salignus ecotype favours wetter areas (more than 500 mm per year), and lower elevations. Different ecotypes often coexist in the same region, but seldom close to one-another. 

Kraaij et al. built up a map of the distribution of Wild Rooibos and its various ecotypes, using data from the Global Biodiversity Information Facility and CapeNature databases, previously published research, and fieldwork carried out by Gerhard Pretorius. As much as possible, sites with historic records of the plants were visited to establish their continuing presence (or absence). Additional observations were made along roads connecting historic observation sites.

This data was then used to build a model of the potential distribution of the species, and the Bush, Prostrate, Erect, and Saligus ecotypes. This was achieved by mapping the presence of the plants against a range of variables, including precipitation in the  warmest quarter; precipitation in the coldest quarter; maximum temperature of the warmest month; minimum temperature of the coldest month; topographical slope; soil electrical conductivity; soil potassium, sodium, phosphorus, carbon, and nitrogen levels, soil pH; and the proportion of sand in the soil. 

Of the 235 sites where the species was historically recorded, it was found to now be absent from 30, and present at 47. In addition, 99 new locations where the species was present were identified. The species was not found at an outlier north of Nieuwoudtville and one east of Vanrhynsdorp, and some locations around Citrusdal, not was it found south of Malmesbury, at Franschoek, on the Cape Peninsula, or in the Gordon’s Bay and Betty’s Bay areas. It was confirmed at De Doorns, the easternmost location where it was previously recorded. Kraaij et al. note that the absence of the species at a site where it was historically recorded does not imply local extinction; it is possible that the previous records were miss-identifications. Notably, the habitat at some of these locations appeared completely unsuitable for Rooibos, with very steep slopes, clay soils, or wetlands, and a plant assemblage different from that associated with Rooibos plants. Some records of the plant in southern areas listed on iNaturalist could be verified, suggesting that it is not absent from the claimed southern extent of its range, but the species mainly occurs in the area between Nieuwoudtville in the north, Groot Winterhoek in the south, Wupperthal and the Tra-Tra mountains in the east, and just southeast of Graafwater in the west.

Results of field verification of historical location records of Wild Rooibos, showing where Rooibos was present, absent or not verified, as well as new location records. Kraaij et al. (2025).

The Wild Rooibos population was predicted to extend from Nieuwoudtville in the north to just southeast of Ceres, with the bulk of its distribution around Clanwilliam and Citrusdal, which was largely in line with predictions based upon previous reports. In total the species occupied an area of about 6000 km², with individual ecotypes occupying areas of between 1500 and 2500 km². The Salignus ectotype was the most abundant, predicted to occupy an area of about 254 600 km², followed by the Prostrate ecotype, 161 200 km², the Bush ecotype, 121 100 km², and the Erect ecotype, 119 900 km². Because each ecotype and the species as a whole were modelled separately, the species total does equal the total for each ecotype minus the overlap between different ecotypes. 

Overlap between ecotypes was only substantial in the core area of the distribution range. The Bush and Prostrate ecotypes had roughly similar distributions, extending east and south of the core area. The Erect and Salignus ecotypes had distributions extending west and north of the core area, with the Salignus ecotype predicted to extend furthest west, beyond Piketberg. The Salignus ecotype was also predicted to be found in the south, around Ceres. 

The distribution of the different ecotypes appeared to be driven by different factors. The distribution of the Bush and Prostrate ecotypes appeared to be influenced by the coldest cool period temperature, with both ecotypes able to cope with sub-zero temperatures. Warm season precipitation was clearly important to these ecotypes as well, with both favouring low summer precipitation. The distribution of the Erect and Salignus ecotypes was most strongly influenced by the concentration of potassium in the soil, with both ecotypes favouring very low concentrations. The Erect ecotype also appeared to need low soil conductivity. The distribution of both Erect and Prostrate Ecotypes was also influenced by the concentration of carbon in the soil with both ecotypes favouring very low levels. Kraaij et al. note that high winter temperatures and wet summers favour the growth of pathogenic Oomycetes such as Pythium spp. and Phytophthora cinnamomi, which are known pests of farmed Rooibos.

Kraaij et al. also produce estimated population sizes for the species and each ecotype. They again note that the total for the species does not match the total for each ecotype added together, as these were calculated separately. Three estimates for each population were made, based upon the minimum, mean, and maximum density of the plants. For the species as a whole, the minimum population was estimated at 14.7 million plants, while the mean was 1.78 billion plants, and the maximum was 17.0 billion plants. The most abundant ecotype, Salignus, was estimated to have a minimum population of 144 million plants, a mean population of 390 million plants, and a maximum population of 630 million plants. For the Prostrate ecotype the figures were, minimum 4.35 million plants, mean 863 million plants, and maximum 4.66 million plants. For the Bush ecotype the figures were minimum 13.3 million plants, mean 325 million plants, and maximum 1.34 billion plants. Finally, for the Erect ecotype, the figures were minimum 3.00 million, mean 189 million, and maximum 833 million plants.

Kraaij et al. recommend, however, that these figures be taken with a good deal of caution, as characterising the species distribution and abundance in the landscape was challenging in many cases, with significant implications for the population estimates. The density of Prostrate plants was particularly hard to estimate, particularly when it was interspersed with other plants. The species has a highly irregular distribution across its range, with plants often forming dense clumps in the midst of apparently similar and equally habitable, but unoccupied, landscapes. Both the size and density of individual populations varied a great deal from site to site. Furthermore, most populations were detected from a moving vehicle, requiring a minimum density for observation; it is possible that less dense populations were overlooked. Finally, Rooibos plants grow in a landscape prone to periodic burning. This does not appear to damage the population as a whole, but the plants do take time to recover after a fire, so their presence is likely to have been missed in areas which had recently burned.

Given these constraints, Kraaij et al. estimate that the populations of the species and each ecotype are probably towards the lower ends of their estimated numbers, but that more detailed surveys of each population would be needed to confirm this.

Much of the population of Wold Rooibos appears to be on protected land. Kraaij estimate that 27% of the total population is found on state or private protected areas, with 38% of the Prostrate ecotype, 33% of the Salignus ecotype, 28% of the Bush ecotype, and 20% of the Erect ecotype occurring on protected land.

About 40% of the Wild Rooiboss population was found to be growing in areas where Kraaij et al. considered that it faced no threats. Another 13% was found in areas where it was prone to illegal harvesting, although this was not thought to present a major threat to the species. About 28% of the population was growing in areas where land transformation presented a threat, although much of this land was probably unsuitable for conservation, and was likely to receive some protection from legislation preventing the clearing of natural vegetation. About 4% of the land where the species grew is potentially threatened by overgrazing, although this does not appear to present a direct threat to Wild Rooibos plants. About 15% of the sites were threatened by invasive plants, particularly Dodder, Cuscuta campestris, a parasitic climbing plant from North America, which can target a wide range of hosts and which is a problematic invasive species in several parts of the world. Cultivated Rooibos fields are known to be prone to invasion by Golden Wreath Wattle, Acacia saligna, and Cyclops Wattle, Acacia cyclops, but while these are a problem in Rooibos fields, they do not seem to be a problem in the natural setting. Potentially, climate change could alter the fire regime in the areas where Wild Rooibos grows. However, the species currently grows in areas where fires are fairly infrequent, with the interval between fires typically significantly longer than the regrowth of the plants, so any shift in fire regime would have to be significant to cause a problem.

Climate change could also potentially alter rainfall patterns and temperature in areas where Wild Rooiboss grows. Since these are variables known to affect the distribution of the plants, this could potentially have a major impact on the species, particularly if winters become warmer and wetter. Two of the populations visited during the study appeared to have suffered widespread mortality events following high summer rainfall events in the summer before being visited. Cultivated Rooibos is also known to be intolerant of waterlogged soils, requiring farmers to implement careful drainage schemes. Since a wetter climate is a predicted outcome of a warming climate in the Western Cape, this could be a major threat to the future of the species. 

Wild Rooiboss does not appear to be at risk from hybridisation. The various ecotypes do not appear to interbreed, even when in close proximity to one-another. Potentially each ecotype could be threatened by inbreeding depression if populations become isolated. As it stands, geneflow within the species is not really understood, though it is likely that geographical barriers such as wide rivers and mountain ranges present a barrier to pollination, and the main distributors of the seeds of the plants are Ants, which do not tend to move long distances. Despite the variety of ecotypes, Wild Rooiboss does not show a great deal of genetic diversity as a species, with even less diversity in the southern part of its range. This lack of diversity could potentially present a threat to the species, and should be considered carefully during any conservation efforts. 

There are more than 9000 fields of Cultivated Rooiboss in South Africa, with 4181 occurring within the natural range of the species as calculated by Kraaij et al. Of the 146 Wild Rooibos populations varified, 55 were found to be within 1 km of Cultivated Rooibos fields. Theoretically, hybridisation between Wild and Cultivated Rooibos is possible, but this was not observed, Cultivated Rooibos plants do not persist well after cultivation ceases, which, combined with the apparently limited gene flow between ecotypes, suggests that hybridisation with the Cultivated form does not present a major threat to Wild Rooiboss populations. 

Wild Rooibos has a limited and fragmented distribution, but within this range appears to be common. The total wild population of the species is estimated to be more than 15 million plants. About 27% of the species distribution lies within protected areas. The species does not appear to be threatened by illegal overharvesting, invasive plants, overgrazing, or fire regimes, nor by hybridisation with the Cultivated form. The potential for habitat transformation appears to present only a minor threat to the species. By far the greatest threat to Wild Rooibos appears to be the potential effects of global warming, potentially bringing warmer, wetter conditions unfavourable to the species. This could well cause the range inhabited by the species to contract, with little potential for migration to better climates without Human intervention. 

See also...

Dyckia semperflorens: A new species of Bromeliad from the cold region of Rio Grande do Sul, southern Brazil.

Bromeliads are herbaceous Monocotyledons native to the Americas (with a single species known from West Africa) and related to the Sedges and Grasses. They have a distinctive rosette shape, with blade-like leaves spiraling out from a central point. In some cases the centre of this rosette forms a water reservoir held in place by tightly overlapping leaf-bases, which can contain entire miniature ecosystems. Many Bromeliads are epiphytes, living on the branches of trees, particularly in rainforests, but others live on the ground and many are found in deserts.

The genus Dyckia contains 188 recognised species of Bromeliads, making it one of the most specious genera within the group. The majority of these are found in arid areas of Argentina, Bolivia, Paraguay, Uruguay, and Brazil, with about two thirds of all species being found in Brazil. Species of Dyckia tend to have spiny leaves and a succulent form, and often grow on thin soils or directly on rock. They also tend to be highly endemic, with most species having a limited geographical range, and several species known only from a single location.

In a paper published in the Nordic Journal of Botany on 17 October 2025, Henrique Mallmann Büneker and Jorge Ernesto de Araujo Mariath of the Laboratório de Anatomia Vegetal and Programa de Pós-graduação em Botânica at the Universidade Federal do Rio Grande do Sul, describe a new species of Dyckia from an escarpment beside the Rio dos Touros in the municipality if Bom Jesus in Rio Grande do Sul State, Brazil.

The new species is named Dyckia semperflorens, where 'semperflorens', means 'continuously flowering'; when the species was first observed in 2017 a live specimen was collected and brought to the Planeta Bromélia nursery in Porto Alegre, where it has remained in bloom ever since. Specimens of Dyckia semperflorens reach 65-96 cm in height, and have a rosette diameter of 38-65 cm. Leaves are 47-107 cm in length, with the inner leaves being semi-erect, while the outer ones are more relaxed, all have an elongate triangular shape with a waxy surface and sparse spines on the edges. Flowers are born on an erect or semi-erect peduncle, 20-36 cm in length. Flowers are tubular and greenish or reddish, flowers on the base of the peduncle are larger than those towards the tip.

Dyckia semperflorens.  (A) Habitat, (B) clumping habit, (C) flowering plant habit, (D) rosette, (E) detail of the inflorescence. Henrique Mallmann Büneker in Büneker & Mariath (2025).

Dyckia semperflorens is known from a single location, on a rocky escarpment along the banks of the Touros River, 1054 m above sealevel, in the municipality of Bom Jesus, Rio Grande do Sul State, in southern Brazil. The local environment is dominated by grassland, with patches of  Araucaria forest. The climate here is temperate, with frost and snowfall in the winter. 

The only known population of Dyckia semperflorens grows in an area currently under pressure from cattle grazing and frequent anthropogenic fires, which are used for grassland management in the region. However, there are other similar areas in the region which could potentially support the species, and which have not been explored yet, so Büneker and Mariath refrain from assigning a conservation status to the species at this time.

See also...

The Holly and the Alphaproteobacterium.

The Family Phyllobacteriaceae comprises a group of 19 genera of Alphaproteobacteria, commonly associated with Plants, with many species associated with nitrogen-fixation, nutrient cycling and bioremediation (converting toxic substances into non-toxic substances), although other species are found free-living in soil or water. Strains belonging to the family Phyllobacteriaceae are usually Gram-stain-negative, rod-shaped, aerobic, non-spore forming and non-motile or motile utilising polar, subpolar or lateral flagella. Many members of the genera Mesorhizobium and Phyllobacterium have Plant-growth-promoting properties, with Mesorhizobium in particular commonly associated with the rhizosphere (root-system and associated biological community) of Legumes, where some species have been shown both to fix nitrogen, which is then utilised by the Plants, and receive carbon compounds from the Plants in return. Members of the genus Aminobacter have also been shown to be capable of fixing nitrogen and in some cases to be associated with the root-nodules of Legumes, although this genus is typically free-living in soil or water, with some species surviving entirely chemolithotropicly, utilising carbon monoxide in the process.

In a paper published in the International Journal of Systematic and Evolutionary Microbiology on 3 November 2025, Sinchan Banerjee of the School of Life Sciences at the University of Warwick, András Táncsics of the Department of Molecular Ecology at the Hungarian University of Agriculture and Life Sciences, Zeqin Wu, Tudor Stafioiu, and Jiacheng Gao, also of the School of Life Sciences at the University of Warwick, Erika Tóth of the Department of Microbiology at Eötvös Loránd University, Erzsébet Baka, also of the Department of Molecular Ecology at the Hungarian University of Agriculture and Life Sciences, and Gary Bending and Hendrik Schäfer, again of the School of Life Sciences at the University of Warwick, describe a new species of Phyllobacterium, derived from the leaves of a Holly tree, with the ability to oxidise carbon monoxide.

Carbon monoxide is a common pollutant, produced by a range of industrial and other Human activities, and deadly to both Human and most Animal life. Notably, it is a significant product of biomass burning, which many countries are looking to as a potential energy source as they try to move away from a dependence on fossil fuels. Carbon monoxide is also produced by a range of natural occurrences, from forest fires to rock weathering, but does not build up in the environment, as it is also removed by a range of biological and non-biological processes. This means that carbon monoxide does not present a global atmosphere-changing threat, in the way that carbon dioxide or methane emissions do, but that it does represent a significant hazard at the local level, and that means of reducing that hazard are of interest to a range of researchers.

The phyllosphere, that part of Plants which is above the ground, presents a novel and often challenging environment for micro-organisms, with fluctuating exposure to heat and ultraviolet radiation, nutrient supplies strictly controlled by the host-Plant, and, frequently, exposure to a range of environmental pollutants. 

Banerjee et al. collected Common Holly, Ilex aquifolium, leaves from Tocil Wood Nature Reserve in Coventry, UK. Leaf-wash preparations were made from these, and stored in vials with the headspace filled with carbon monoxide. Samples where the carbon monoxide level was found to drop were placed on agar plates, and incubated at 25°C for five days, to promote Bacterial growth. 

The resultant colonies were subject to 16S rRNA gene sequence analysis, which established that Banerjee et al. had found a novel Barcterial strain, which they identified as SB112ᵀ. This strain was then subjected to a full genome phylogenomic analysis, establishing that it was a novel species of Phyllobacterium, related to the genus Mesorhizobium. 

Since SB112ᵀ does not appear to fir into any currently designated genus, Banerjee et al. assign it to a new genus, which they name Foliimonas, which is derived from 'folium' meaning 'leaf' and 'monas' meaning 'unit' (a common suffix for Bacterial names), and give it the specific name ilicis, meaning 'of the Holly Tree'.

Phylogenomic tree constructed using Up-to-date Bacterial Core Genes (concatenated alignment of 92 core genes) showing the phylogenetic position of Foliimonas ilicis (SB112ᵀ). For inferring the tree, the FastTree algorithm was used. Bar represents 0.02 substitution per nucleotide position. Banerjee et al. (2025).

Foliimonas ilicis is a Gram- reaction- negative, aerobic, rod-shaped Bacterium, which is motile with a polar flagellum. Cells have an average length of 1.18 μm. The species has an optimum growth range of 20-37°C, with growth stopping completely below 4°C. Foliimonas ilicis can oxidise carbon monoxide, but is unable to reduce nitrous oxides of ferric citrate. It produces esterase (C4), esterase lipase (C8), leucine arylamidase, acid phosphatase, naphthol-AS-BI-phosphohydrolase, valine arylamidase, cystine arylamidase and trypsin, but not urase. It could assimilate d-glucose, l-arabinose, d-mannitol, d-mannose, potassium gluconate and malic acid, and metabolise l-arabinose, d-xylose and xylitol.

Transmission electron microscopic photograph showing cell morphology and presence of flagella in Foliimonas ilicis. Scale bar is 1 µm. Banerjee et al. (2025).

See also...

Tracing the origin of Azobé wood from Cameroon, Gabon, and the Republic of Congo.

Illegal logging is a serious problem in many of the world's forests, damaging ecosystems, undermining sustainable management practices, and fuelling other forms of crime. It has been estimated that between 8% and 29% of all internationally traded timber has been harvested illegally, which would make the illegal trade in wood the world's third largest form of trans-border crime. This problem is particularly acute in tropical regions, for example the proportion of internationally traded timber from Central Africa thought to have been taken illegally is thought to be between 50% and 90%. Many timber importing countries have legislation which require importers to show that timber has been sourced legally, with data on both the origin and species of wood required, but this is often difficult to prove, and current international trade systems are thought to be rife with abuse. The new European Union Regulation on Deforestation Free Products, which is due to come into effect on 30 December 2025, mandates that timber importers demonstrate that timber has been sourced legally, and in a way that does not contribute to deforestation, and also requires that exact geolocations are provided for each piece of timber. However, independently verifying both the species of tree from which wood originates and the location from which it was obtained is likely to prove challenging.

A variety of methods have been used to try to verify the origins of timber, including the anatomy of the wood, genetic identification, near-infrared spectroscopy, mass spectroscopy, and stable isotope analysis. These methods have proven effective in identifying wood to the species level, but much less effective at determining its point of origin, leaving tracing efforts reliant on external documents, tags, or scans, all methods which are known to be vulnerable to fraudulent practices. Methods such as genetic analyses, stable isotope ratios and multi-element analysis, have failed to achieve the level of accuracy needed to track tropical timbers effectively, at least in part because of a lack of variation between samples.

In a paper published in the journal Communications: Earth & Environment on 15 October 2025, a team of scientists led by Laura Boeschoten of the Forest Ecology and Forest Management Group at Wageningen University & Research, and the Department of Ecology, Evolution and Environmental Biology at Columbia University, and Barbara Rocha Venancio Meyer-Sand also of the Forest Ecology and Forest Management Group, and of the Forest and Nature Conservation Policy Group at Wageningen University & Research, describe a multi-variant method which combines genetic analysis, stable isotope ratio analysis, and multi element analysis to trace the origin of Azobé, or Red Ironwood, Lophira alata, timber from locations in Cameroon, Gabon, and the Republic of the Congo. 

Azobé logs from Gabon. WoodPro Industries.

Boeschoten and Meyer-Sand et al. reasoned that these different methods can present complementary information when trying to determine the origin of wood, and note that similar methods have been used to trace a range of agricultural commodities, wood from archaeological sites, and timber from temperate forests. Central Africa presents an ideal test area for the use of these methodologies in a tropical context. Levels of illegal logging are known to be high, there is an absence of the type of geographical barriers which lead to genetic isolation, and limited variations in climate, topography, bedrock, or soil type, all of which tend to hamper single-method tracing, but which leave open the possibility of multi-technique methodologies providing sufficient data to allow for accurate tracing of wood samples. To this end, Boeschoten and Meyer-Sand et al. combined genetic, isotopic, and elemental tracing methods, to evaluate if, in concert these could provide a reliable method to trace timber from Central Africa.

For trees, a genetic landscape can often be determined through the distribution of genetic traits within a population, which in turn is determined by reproductive, demographic and historical biogeographic factors, such as seed and pollen dispersal, topographic barriers like rivers and mountain ranges, and evolutionary history, including glaciation cycles during the Pleistocene that led to forest refugia. Genetic methods have been used to determine the origin of timber on a regional scale, for example to differentiate between West African and West African timber, and has sometimes proven useful at identifying the country of origin for wood, with a few cases of the method being used to differentiate timbers at shorter ranges. 

Stable isotope ratios represent the proportion of isotopes such as oxygen¹⁸, hydrogen² (deuterium), carbon¹³, nitrogen¹⁵, and sulphur³⁴ within the total samples of their respective elements from a sample. While these isotopes have the same chemical properties as the more common isotopes of the same elements, they have different masses, and therefore are subject to sorting by some biological, geological, and environmental processes. This method has been used extensively in timber tracing from other regions, and has proven effective as a way of differentiating timbers from locations very distant from one-another, with a higher spacial definition achieved in areas where local isotopic variations tend to be larger, such as in mountain ranges. This method is often combined with element analysis. In Central Africa, some studies have found this to be an effective way to tell timber from different locations apart, but in other areas little difference has been seen between remote locations within the same country.

Multi-element analysis works by measuring the proportions of elements such as magnesium, calcium, and lanthanum in wood samples. These elements are not vital for the survival of trees, but are taken up with ground water during transpiration, then deposited into the tissues of the plant. The proportion of each of these elements present reflects the chemistry of the soil and underlying bedrock. This method can be quite efficient at differentiating the origin of timber over small distances, but is less accurate over larger areas. It has been combined with stable isotope analysis to determine the origin of some timbers from Eastern Europe.

Azobé timber is widely traded in the Congo Basin due to its dense, durable, and decay-resistant wood, which can be used for structures such as roads and jetties. The species is listed as Vulnerable on the International Union for the Conservation of Nature's Red List of Threatened Species, due to heavy harvesting of the trees, destruction of the forests where they grow, and a slow growth and regeneration rate. Boeschoten and Meyer-Sand et al. sampled 234 Azobé trees at 23 locations in Cameroon, Gabon, and the Republic of Congo, with the two closest sites being 15 km apart, and the two most remote separated by a distance of over 1000 km. Samples were tested for chloroplast genome-wide single-nucleotide polymorphisms (individual gene variations from chloroplasts, which do not undergo genetic recombination each generation, but are inherited from the mother Plant in the same way as mitochondria), the proportions of the isotopes oxygen¹⁸, hydrogen², and sulphur³⁴, and the presence of 41 elements, including trace elements known to be used by plants as well as 16 rare earth elements.

Overview of the three methods for timber tracing in this study and their drivers of geographic variation. Possible drivers of geographic variation shown as examples are: (1) For single-nucleotide polymorphisms (SNPs): former forest refugia during cold Pleistocene glaciation cycles with refugia in dark and forest cover in light green. (2) For stable isotopes: the oxygen isotope signal in rainwater, with higher rainwater the proportion of oxygen¹⁸ in lighter blue. (3) For multi-element analysis: soil clay content ranging from high clay % in green, mid-levels of clay % in yellow and low clay % in pink. Boeschoten & Meyer-Sand et al. (2025).

The primary focus of the study was to address origin identification ('Where did this timber come from?'), with origin verification ('Does this timber come from the stated place of origin?') being a secondary question. Origin identification is considered to be a crucial step in the creation of forensic methods, as it gives insight into variation across different points of origin, and is therefore the most widely used metric in studies; making this essential to compare the value of one particular study to those carried out by other research groups. However, Boeschoten and Meyer-Sand et al. note that origin verification is the more common goal of forensic studies, so both aims were included in the study.

The genetic analysis identified three main genetic clusters, as well as recovering previously identified genetic splits, including one which divides the Lower Guinean Region, and another that follows the Cameroonian Volcanic Line. The largest of these three clusters incorporated ten sites in West Cameroon, to North￾West Congo and Central-East Gabon, with two sites in West Cameroon forming a distinct sub-cluster. The second cluster was located in West Gabon, and was the most genetically distinct, potentially representing an unknown cryptic species of Lophira. The third group was located in the Northern Congo, and again represents a distinctive, and previously unknown genetic population, although in this case probably not distinctive enough to merit being identified as a separate species. 

Despite this apparent distinctiveness, genetic analysis of individual samples was only able to place them at the correct site of origin 46.2% of the time, with 62.2% of trees identified to a location within 100 km of where they grew and 85.6% to within 300 km. All trees were placed within 500 km of their growing sites.

An Azobé tree growing in Cameroon.  Biwolé et al. (2019).

Stable isotope ratios were found to vary a great deal, with the variation between trees at the same site often as great as that between trees at sites hundreds of kilometres away. Some patterns could be observed, particularly with regard to hydrogen², but even when all isotopes examined were included, it was possible to identify the site of origin for a sample only 40.7% of the time, and to place a tree within 100 km of its location only 49.8% of the time. Trees were frequently placed more than 1000 km from their actual location.

Levels of trace elements varied from between 0.001 g per kg for ytterbium and 4 g per kg for potassium. There were clear differences between sites, and trees could be placed at the correct site 73.4% of the time, and within 100 km 81.3% of the time. The elements tungsten, barium, molybdenum, potassium, and chromium were most useful in determining sample origins. Trees could be placed accurately at two sites in Cameroon 100% of the time, although some trees from other sites were still misplaced by more than 1000 km. 

Confusion charts for the identification of wood samples to their respective origin. Identification was based on (A) single-nucleotide polymorphisms (SNP), (B) three stable isotope ratios (ISO), and (C) multi-element analysis of 44 trace elements (EL) and D all three combined. Mean identification accuracy across all sites is indicated in the bottom left. Each site has a unique colour, shown in the inner circle and in the legend. Colours in the outer circle of each symbol indicate to which (other) site(s) the trees of that site were assigned. Primary tropical forest extent from Global Forest Watch is indicated in grey. Boeschoten & Meyer-Sand et al. (2025).

Combining any two of these methods proved to be more accurate than any method on its own, confirming that using a combination of methods was a valid approach. Combinations which included the multi-element analysis were particularly efficient, with a combination of multi-element analysis and single-nucleotide polymorphic genetic analysis placing trees at the correct site 79.8% of the time, while a combination of multi-element analysis and stable isotope analysis achieved this 77.3% of the time. When all three methods were combined, trees were placed at the right site 86.9% of the time, within 50 km of that site 91.0% of the time, and within 100 km of that site 94.5% of the time. When all three methods were used in combination, no tree was placed more than 500 km from its site of origin. Individual sites varied in the method which showed the most accuracy, with some sites being identifiable using only a single method. Notably, however, some sites which did not achieve high levels of accuracy with any single method achieved 100% accuracy with a combination of the three.

The combination of methods used by Boeschoten and Meyer-Sand et al. compares well to previously tried methods when attempting to identify the point of origin of samples. However, the question most commonly asked by forensic scientists working with timber-trade regulators is not 'Where did this timber come from?', but 'Does this timber come from where it is supposed to come from?'. In order to assess this, 41 samples were removed from the dataset, which was then recalibrated without them. Each sample was then tested against two claims, firstly that it came from the site that it genuinely came from, and secondly that it came from a randomly chosen alternative site. In this second scenario, all trees from the same site as the tree being tested were excluded, to simulate a tree from a genuinely unknown source, which would not be present in the database.

In the scenario where samples were tested against the correct site of origin, the test identified the sample correctly with an accuracy of 87.8%, whereas for the second test, testing a sample against an incorrect point of origin, the correct answer was produced 95.4% of the time. A purely random test would have identified samples from the correct site only 7.7% of the time, whereas it would have excluded samples from the wrong site 91.7% of the time. Thus, while the second test appeared more accurate, it was not a notable improvement on random chance.

Origin fraud is a major problem for the international timber industry, and no testing method has proven to be completely reliable in all settings. Regions such as Central Africa, where there are few geographical barriers and little environmental variation, are particularly problematic. By using three different methods together, Boeschoten and Meyer-Sand et al. were able to reach a level of tracing accuracy better than had previously been obtained for the region, with 94.5% of wood samples assigned within 100 km of their origin and 91% within 50 km. When the method was used to test timber against claimed points of origin, it correctly confirmed true claims 87.8% of the time and rejected false claims 95.4% of the time.

The 800 m-long Blauwe Loper Bridge in the Netherlands is Europe's longest cycle bridge. It was constructed using Azobé wood from Forest Stewardship Council certified sources. The durable nature of the wood means that it is predicted that it will not need to be replaced for 80 years. About 450 tonnes of Azobé wood was used in the construction of the bridge. Fair & Precious.

Combining the three methods provided a greater level of accuracy than using any single method. This is because each variable is driven by a different set of conditions, resulting in a higher level of differentiation, even in a relatively homogeneous environment. The technique was particularly good at placing samples within 50 km of their point of origin compared to other methods, which corresponds roughly to the scale at which soil properties vary. The inclusion of genetic data considerably improved the resolution achieved, even though the lack of geographical barriers resulted in only a gradual genetic change between the sites. 

The method compared well to previous studies which have only used a single technique to try to identify timber from the region, and Boeschoten and Meyer-Sand et al. anticipate that methods using multiple different forms of analysis will prove to be useful in areas where environmental gradients are low, but high resolution testing is required. Legal requirements around sourcing timber sustainably are likely to tighten in consumer countries in the future, which will require more reliable methods of testing claims about the origin of timber, as well as for commodities such as palm oil, soy, rubber, beef and cocoa. The methods chosen to verify the origin of such commodities will likely vary, but for items such as timber from the Congo Basin, where fraud is considered to be a significant problem, testing methods will need to be demonstrably reliable with a high degree of accuracy.

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