Three Rare Plants Face Extinction as New Global Red List Assessments Reveal

Three vascular plants from Uzbekistan and Sicily have just received their first formal global extinction risk assessments under the International Union for Conservation of Nature (IUCN) Red List categories and criteria, and the results are sobering. Two of the species — a desert onion and a mountain wild kale — are now classified as Critically Endangered, while a third onion relative is listed as Endangered. The assessments, published in the journal Italian Botanist, document how restricted ranges, tiny populations, mining expansion, overgrazing, and intensifying drought are converging to push these plants toward extinction. Together, they illustrate a pattern familiar to conservation biologists worldwide: narrow endemics clinging to specialized habitats are often the first casualties of human pressure and climate change.

The first species, Allium eremoprasum, known commonly as the desert onion, is a bulbous perennial growing 10 to 25 centimeters tall. It is a national endemic of Uzbekistan, found only in the central part of the country in Nurabad District of Samarkand Region and in Nurata and Khatyrchi Districts of Navoi Region, on the Aktau Range and Zirabulak mountains in the north-western branches of the Pamir-Alay mountain range. Only nine localities are known to date. The plant grows on rock ledges and crevices, screes, and dry stony slopes on lithosols and calcic xerosoils derived from limestones, marbles, granites, and schists, at altitudes from 700 to 1,600 meters above sea level. It flowers in May and June and fruits in June and July, propagating by seeds and bulblets, though its reproductive biology has never been studied in detail.

The population of Allium eremoprasum is estimated at roughly 300 to 500 mature individuals, occurring solitary or in small isolated groups of 3 to 30 plants. Two subpopulations are recognized — a smaller one in the Zirabulak Mountains and a larger one in the Aktau Range — separated by approximately 50 to 60 kilometers of the Zeravshan River valley, which has been largely transformed by irrigated arable lands and settlements since ancient times, preventing gene flow between the two groups. Notably, after 1926, not a single occurrence record of the species was known from the Zirabulak Mountains, where it was first described. The subpopulation there is almost certainly nearly collapsed, and an estimated population decline of about 20 percent has occurred over the past 100 years. The most serious direct threat is mining and quarrying — gold, marble, crushed stone, and rubble quarries are intensively developed in both mountain ranges, and illegal gold mining by local people also occurs. A planned wind power plant in the Zirabulak Mountains would further degrade remaining habitat. Overgrazing by goats poses a minor direct threat, while mudflows eliminate significant numbers of seedlings and young plants.

Applying IUCN Criterion B, the extent of occurrence for Allium eremoprasum was calculated at 1,857.65 square kilometers using GeoCAT software, and the area of occupancy at 40 square kilometers using 2-by-2-kilometer cells. The distribution is severely fragmented into two subpopulations separated by a geographical barrier, with continuing decline observed in extent of occurrence, area of occupancy, extent and quality of habitat, number of subpopulations, and number of mature individuals. Under Criterion C, the population size is less than 2,500 mature individuals, and the largest subpopulation holds fewer than 250. The species therefore meets the thresholds for Endangered (EN) under the criteria EN B1ab(i, ii, iii, iv, v)+2ab(i, ii, iii, iv, v); C2a(i). Although a significant part of the largest subpopulation grows within the Aktau wildlife sanctuary, a Category IV protected area, the species is included in the latest edition of the Red Data Book of Uzbekistan under category 2, corresponding to IUCN category EN. It has only recently been cultivated ex situ, and its seeds are not stored in any germplasm bank. Conservationists recommend restricting or prohibiting mining, quarrying, and goat grazing within the species’ habitat, along with targeted research and ex situ cultivation in botanical gardens and seed banking.

The second assessed species, Allium svetlanae or Svetlana’s onion, is a bulbous perennial 15 to 60 centimeters tall that grows in clusters. It is a narrow endemic to the Nuratau Range in Uzbekistan, confined to the middle reaches of the small river Ustuksay on the southern slope, in Koshrabad District of Samarkand Region — outside the strictly protected area of the Nuratau State Nature Reserve. Unlike its desert relative, Allium svetlanae is a wetland specialist, intolerant of dry conditions. It inhabits a narrow rocky gorge with steep slopes, growing on damp nutrient-rich alluvial soils along mountain streams, near springs, and on wet granite rocks at altitudes from 1,200 to 1,500 meters. It flowers in June and July and fruits in July and August, sometimes forming dense clumps alongside other hydrophilic species such as Calamagrostis pseudophragmites, Carex diluta, Juncus articulatus, and Mentha longifolia var. asiatica.

The single known population of Allium svetlanae was estimated at approximately 5,000 to 10,000 mature individuals during field studies in 2013. However, surveys in 2024 and 2025 revealed a dramatic reduction: the population now consists of roughly 2,500 to 3,000 plants, representing a decline of 54 percent in the number of individuals over just the last 10 years. The reduction stems from the combined effects of climate aridization, mining operations, and the drying up of springs and streams due to extensive pasture load. Overgrazing in the Nuratau Range mountain pastures leads to soil erosion, changes in the hydrological regime, and the drying up of springs — a serious indirect threat even though the plant grows in a gorge inaccessible to livestock. Gold deposits in the Nuratau Range have been intensively studied and developed in recent years, and illegal gold mining occurs in the Ustuksay valley, posing the most serious direct threat that could lead to the irreversible loss of the entire population. Regular droughts and increasing desertification compound the problem. Species distribution modeling demonstrates that under the RCP8.5 climate scenario, the suitable range for Allium svetlanae will decrease significantly with further aridization, and extinction risk will increase.

Applying IUCN Criterion B, both the extent of occurrence and the area of occupancy for Allium svetlanae were calculated at just 12 square kilometers, with only one location known and continuing decline observed in the extent and quality of habitat and the number of mature individuals. The species meets the quantitative requirements for Critically Endangered (CR) under the criterion B1ab(iii, v), given that the extent of occurrence is less than 100 square kilometers, a single population is known, and there is an observed continuing decline in habitat quality and mature individuals. Alarmingly, Allium svetlanae has never been included in any edition of the Red Data Book of Uzbekistan, is not protected in situ, has only recently been cultivated ex situ, and its seeds are not conserved in any germplasm bank. Ongoing initiatives such as the Digital Nature project — a digital platform for the flora and fauna of central Uzbekistan — are already being implemented to support research, monitoring, and conservation planning. Recommended actions include expanding the borders of the Nuratau Nature Reserve or establishing a new protected area, prohibiting mining and geological exploration at the only known location, regulating pasture load, and encouraging ex situ cultivation and seed banking.

The third species, Brassica trichocarpa, is a wild kale discovered in 2012 on a calcareous rocky ridge at 950 meters above sea level near Monte Cuccio, within the municipality of Palermo in Sicily, Italy. Known locally as Cavolo del Monte Cuccio, it is a biennial or perennial suffruticose chamaephyte occurring exclusively along a single narrow ridge of calcareous rocks within thermo-xeric grassland dominated by Ampelodesmos mauritanicus. It is considered to belong to the Brassica oleracea complex, which includes insect-pollinated taxa with variable levels of self-sterility, and its most probable dispersal strategy is barochory — the simple dropping of seeds by gravity. Preliminary germination tests at the University of Catania indicate that after ten days at 25 degrees Celsius in the dark, 6 out of 10 seeds regularly germinated. Its chromosome number has not yet been verified but is assumed to be 2n = 18.

At the time of its discovery, the population of Brassica trichocarpa was estimated at approximately 50 individuals. In the last couple of years, field observations have recorded a dramatic reduction: in June 2024, only one reproductive plant and 4 to 5 vegetative plants could be counted, distributed within an area of no more than 2,500 square meters. The main cause of this collapse is likely the increasing and regular raising of fires in the area each summer — a criminal practice that prevents new seedlings from reaching their reproductive stage, which requires at least one year. Grazing by cows poses a potential additional threat, as the animals have been observed reaching the tops of ridges near the wild kale owing to poor maintenance of fences intended to keep herds at lower altitudes. The plant is highly palatable and succulent, attracting herbivores especially during dry periods, so chances to extend the population’s area of growth are severely limited.

Applying IUCN Criterion B, both the extent of occurrence and the area of occupancy for Brassica trichocarpa were calculated at just 4 square kilometers, with only one location known and continuing decline observed in extent of occurrence, quality of habitat, and number of mature individuals. Under Criterion D, only one mature individual remains in the population. The species therefore meets the thresholds for Critically Endangered (CR) under the criteria B1ab(ii, iii, v)+B2ab(ii, iii, v)+D. When first described in 2013, it was evaluated as Critically Endangered, though it was subsequently classified as Nearly Threatened in 2018 — a status now clearly untenable. The species grows within a Natura 2000 Special Area of Conservation, and an intervention targeted at safeguarding and improving natural habitat was funded by the European Regional Development Fund with 871,000 euros between October and December 2021. Unfortunately, no signs of effective management were observed: burned pine forest indicates recent fires, while the old iron fence meant to contain cattle remains pulled down in several places. Ex situ conservation has not been carried out so far, and the species is not listed in the European Search Catalogue for Plant Genetic Resources. In June 2024, a few seeds from the single existing fruiting plant were collected by the University of Catania for conservation and research purposes. The primary action needed is to multiply these recently collected seeds, store them in multiple locations for long-term conservation, and potentially reintroduce them in situ, alongside rebuilding proper cattle fencing, enacting severe fire prevention measures, and conducting research with minimal impact on the remaining wild population to verify seed viability, understand self-incompatibility levels, and assess genetic diversity.

Subject of Research: Global IUCN Red List conservation assessments of three endemic vascular plant species from Uzbekistan and Sicily

Article Title: Global and regional IUCN Red List Assessments: 19

Article References: Fenu, G., Beshko, N. Y., Branca, F., Khabibullaev, B. S., Ilardi, V., Maggioni, L., Shomurodov, K. F., & Orsenigo, S. (2025). Global and regional IUCN Red List Assessments: 19. Italian Botanist, 20, 187-200. https://doi.org/10.3897/italianbotanist.20.177927

Image Credits: AI Generated

DOI: 10.3897/italianbotanist.20.177927

Keywords: IUCN Red List, Allium eremoprasum, Allium svetlanae, Brassica trichocarpa, Uzbekistan, Sicily, endemic plants, plant conservation, biodiversity, mining threats, climate aridization, Critically Endangered