A third of the tropical African flora is potentially threatened with extinction.

Preserving tropical biodiversity is an urgent challenge when faced with the growing needs of countries. Despite their crucial importance for terrestrial ecosystems, most tropical plant species lack extinction risk assessments, limiting our ability to identify conservation priorities. Using a novel approach aligned with IUCN Red List criteria, we conducted a continental-scale preliminary conservation assessment of 22,036 vascular plant species in tropical Africa. Our results underline the high level of extinction risk of the tropical African flora. Thirty-three percent of the species are potentially threatened with extinction, and another third of species are likely rare, potentially becoming threatened in the near future. Four regions are highlighted with a high proportion (>40%) of potentially threatened species: Ethiopia, West Africa, central Tanzania, and southern Democratic Republic of the Congo. Our approach represents a first step toward data-driven conservation assessments applicable at continental scales providing crucial information for sustainable economic development prioritization.

Relationships among "ancient araliads" and their significance for the systematics of Apiales.

The relationship between the angiosperm families Apiaceae and Araliaceae (order Apiales) has been difficult to resolve, due in large part to problems associated with taxa characterized by a mixture of features typical of both families. Among such confounding groups are the araliads Delarbrea, Pseudosciadium, Myodocarpus, Mackinlaya, and Apiopetalum and many members of Apiaceae subfamily Hydrocotyloideae. Traditional systems have often envisioned these taxa as phyletic intermediates or bridges between the two families. To reevaluate the phylogenetic position of the "intermediate" araliad genera, molecular data were collected from nuclear (rDNA ITS) and plastid (matK) sequences from a complete or near-complete sampling of species in each genus. When analyzed with samples representing the other major clades now recognized within Apiales, results confirm and expand the findings of previously published studies. The five araliad "intermediates" are placed within two well-supported clades clearly segregated from the "core" groups of both Apiaceae and Araliaceae. These segregate clades closely parallel traditional definitions of the araliad tribes Myodocarpeae (Delarbrea, Pseudosciadium, and Myodocarpus) and Mackinlayeae (Mackinlaya and Apiopetalum), and relationships among the species within these clades are largely supported by morphological and anatomical data. Based on these results, Myodocarpeae and Mackinlayeae may best be treated as distinct families. This approach would render four monophyletic groups within Apiales, to which a fifth, Pittosporaceae, cannot at present be excluded. Sampling of taxa from Hydrocotyloideae remains preliminary, but results confirm previous studies indicating the polyphyly of this subfamily: hydrocotyloid taxa may be found in no fewer than three major clades in Apiales.