The fern of Achala Asplenium achalense Hieron. (Aspleniaceae), endemic to north-west and central Argentina, was formerly considered a lost species. We describe its rediscovery in August 2022 in the Yungas biogeographical province, compile a map of all historical and current records of the species, and propose an IUCN Red List status. We estimated the fern of Achala's range using the area of occupancy of the rediscovered population, calculated as 4 km2 because it is located in a single 2 × 2 km grid square. The extent of occurrence cannot be calculated because only a single living population is known. These data suggest a provisional categorization of the fern of Achala as Critically Endangered based on criteria B2ab(i,ii,iii,iv,v). The species should be considered Regionally Extinct in its locus classicus in Comechingones biogeographical province. We recommend securing the conservation of the single known population (which does not lie within a conservation unit), further surveys for the species in the five protected areas where it was recorded historically, and restoration of the species in the wild. To support the latter, we are cultivating spores and gametophytes of the fern of Achala, in collaboration with colleagues from the National University of La Plata.

Nymphaea thermarum Eb. Fisch. (family Nymphaeaceae) is a small waterlily endemic to Rwanda that has been categorized as Extinct in the Wild since 2010. We report the rediscovery of N. thermarum in July 2023, not far from its locus classicus, identify the current and potential threats to the wild population (mining and overharvesting by collectors, respectively) and recommend the urgent conservation measures and research required to save the species from extinction. The species occupies small muddy ditches fed by hot spring water used for avocado plantations and fish pools. The population comprises hundreds of individuals, including reproductive adult plants, and seedlings. In the short term, conservation actions should include land protection, negotiation to ensure that sufficient water is reaching the habitat of N. thermarum and the reassessment of the species on the IUCN Red List, probably as Critically Endangered. In the medium term, the creation of a nature reserve, the restoration of the areas already affected by mining, and the reintroduction of N. thermarum to its original site would support long-term in situ conservation of the species. Further research should clarify the total and effective population size, population structure, ecology and genetics of this species.

Wenchengia alternifolia (Lamiaceae) is a plant species endemic to Hainan Island, China. Since the 1930s it was known from only four collections and was believed to be extinct until a remnant population was rediscovered in 2010. We conducted further field surveys during 2010–2012 but located only one population, with 66 individuals. W. alternifolia is restricted to the c. 1,500 m2 Shuangximu Valley, in a harsh microenvironment surrounded by plantations. As the population comprises < 50 mature individuals, we propose that W. alternifolia be categorized as Critically Endangered on the IUCN Red List, based on criterion D. We recommend that the remnant population and its habitat need urgent protection and monitoring and that ex situ conservation, for future reintroduction, should be implemented.

Croton josephinus Müll.Arg., a member of Croton sect. Medea (Klotzsch) Baill. (Euphorbiaceae), has not been recollected since 1824, nor mentioned in the literature since its original publication in 1873. This species has recently been rediscovered in a campo rupestre area at the ‘Pico 1430 m’ of the Serra de São José, Minas Gerais, after 20 years of field work in the area. In the protologue Croton josephinus was cited as having been collected from São Paulo State. This is likely to have been a simple misattribution of the area where it occurs. Based on the new material collected, a detailed description and an illustration of the species are provided. A lectotype and an isolectotype are designated.