The diversity of Vanilla Mill. in Andean South American countries remains significantly understudied, highlighting the urgent need for a robust taxonomic framework as a foundation for future biogeographic, monographic, phylogenetic, and ecological research. Drawing on extensive herbarium studies and fieldwork conducted by the authors over the past decade, we present a curated checklist of this economically important genus in South America, focused on the Andean countries of Bolivia, Colombia, Ecuador, and Peru. Our review records 31 Vanilla species across the four countries, with Colombia emerging as the most species rich, followed by Peru, Ecuador, and Bolivia. Among this diversity, we identified 25 species of potential interest as crop wild relatives of the globally cultivated V. planifolia Andrews. Moreover, we report several species not previously documented in our study area, including a new species from Ecuador, which we describe here as V. sekut Damián, Garzón & Bentley. As part of our extensive herbarium and literature revision, we also designate six lectotypes, one neotype, and four epitypes. This checklist provides a critical baseline for future monographic and evolutionary studies on Vanilla in South America, offering valuable insights into its biodiversity and potential for agricultural and ecological applications.

Hibiscus L. sect. Lilibiscus Hochr. comprises 31 species, the majority of which occur on volcanic islands in the Indian and Pacific Oceans. Four species are currently described in the Mascarene Archipelago: H. boryanus DC., H. fragilis DC., H. genevei Bojer, and H. liliiflorus Cav. Though they are a small group, the Mascarene species in section Lilibiscus have a complex taxonomic history. While type collections and species descriptions are sufficiently detailed to apply the existing names H. liliiflorus and H. genevei to species, the brief species descriptions and insubstantial type collections of H. boryanus and H. fragilis have complicated the application of these two names to the remaining two species. In addition, morphological variation within H. boryanus s.l. as it is currently delimited suggests that the name comprises three distinct species. Thus, the names H. boryanus and H. fragilis could each be applied to one of four species, leaving two species to be described. To determine the proper application of the names H. boryanus and H. fragilis, we conducted a thorough study of herbarium specimens and species descriptions combined with morphometric analyses of seven floral characters obtainable from the 220-year-old type specimens of H. boryanus and H. fragilis and 70 other flowering specimens. Although morphometric analyses were sufficient to determine that the name H. fragilis is best applied to the red-flowered species in Mauritius, additional lines of evidence inferred from the original description of H. boryanus were necessary to apply this name to the yellow-flowered species in Réunion. Consequently, we describe two new species formerly treated under H. boryanus s.l.: a magenta-flowered species endemic to Mauritius (H. dargentii Mashburn) and a red-and-yellow–flowered species endemic to Réunion (H. igneus Mashburn). We provide an identification key to differentiate the Mascarene Hibiscus sect. Lilibiscus species and new and updated species descriptions for all six species.

The Sierra Nevada de Santa Marta (SNSM) is a large, isolated mountain on Colombia’s Caribbean coast. Its isolation has led to high diversity and endemism in its fauna; however, knowledge of the mountain’s floristics remains limited. Here, we aim to better characterize the flora of the SNSM above 1700 m.s.m. Using occurrence records and a literature review, we compile a list of all known seed plants endemic to the SNSM montane flora and perform biogeographical analyses to compare the cloud forest and páramo floras of the SNSM to those of surrounding mountain ranges in the northern Andes and Central America. We first compared broad patterns in collection efforts and species diversity across mountain ranges. We then analyzed the elevational limits of plant species on the SNSM and surrounding mountain ranges to test for the Massenerhebung effect (i.e., the phenomenon that species have higher elevational limits on large mountains rather than small mountains). Finally, we performed a cluster analysis to explore compositional similarities among floras. We identified 164 plant species that are endemic to the SNSM and that occur above 1700 m.s.m., the largest list of SNSM endemics to date. Overall, the SNSM has lower plant diversity than surrounding mountain ranges but also much lower collection effort, indicating a need for continued botanical exploration of the mountain. Our analysis supported the Massenerhebung effect, with the SNSM showing lower elevational limits when compared to larger mountain ranges. The cloud forest and páramo floras of the SNSM were most similar to those of the Cordillera de Mérida in Venezuela. Our results highlight the importance of increasing efforts to explore and conserve the SNSM’s unique flora.

A series of Bayesian molecular clock analyses with varying model combinations, parameters, and tree topologies were conducted to establish a temporal evolutionary framework of land plants and to estimate the age of angiosperms. The data consisted of five organellar and nuclear genes, 633 taxa, and 23 fossil calibration points (FCPs). The analyses were evaluated using an internal search thoroughness measure, effective sample sizes, and two external criteria: the consensus land plant phylogeny and a newly developed method that used the Hennigian reciprocal illumination principle to compare molecular age estimates of 21 nodes representing major land plant clades and the root split in green plants with those of their fossils in an a posteriori fashion. The results show that an analysis using a general time reversible (GTR) DNA substitution model, log normal branch-rate distribution, and Yule tree prior represented the best model combination, with the Birth-Death tree prior being equally optimal. This analysis estimated the age of the land plant crown group as 496.95 million years (MY), with a 95% highest posterior density (HPD) of 465.66–531.43 MY, and the age of the angiosperm crown group as 219.93 MY, with a 95% HPD of 184.09–256.82 MY. The former agrees with the fossil evidence, but the latter is significantly older than the fossil ages. A thorough examination of fossil evidence of angiosperms, as well as their evolutionary history in light of recent knowledge of morphology, physiology, and atmospheric CO2 concentration in the Mesozoic era, suggests that angiosperm radiation might have been delayed after their origin and that the current fossil record probably reflects only the products of that radiation, not the origin of angiosperms. Overall, the study shows that both molecular clock analyses and fossil studies, while agreeing on some aspects but disagreeing on others, can help develop a complete understanding of the temporal evolutionary history of land plants.

The genus Alternanthera Forssk. (Amaranthaceae) is widely distributed throughout tropical and subtropical areas of the Americas. It includes herbs or suffrutices with opposite leaves, perfect flowers protected by a bract and two bracteoles, with capitate stigma and appendages in the staminal tube (or pseudostaminodes) arranged alternately with the stamen filaments, which bear functionally unilocular anthers. Here, a taxonomic revision of the 31 species of Alternanthera that inhabit the Southern Cone and Bolivia is presented. The name A. piptantha Pedersen is synonymized with A. altacruzensis Suess. Type species are designated for genera Brandesia Mart., Bucholzia Mart., Mogiphanes Mart., Steiremis Raf., and Telanthera R. Br. In addition, lectotypes are designated for Achyranthes porrigens Jacq., Alternanthera mexicana (Schltdl.) Hieron. var. gracilis Suess., A. nodiflora R. Br. var. linearifolia Moq., A. tenella Moq., Gomphrena elongata Willd. ex Roem. & Schult., T. meyeriana Regel & Körn, T. rufa (Mart.) Moq. var. glabrata Seub., and a second-step lectotype for A. denticulata R. Br. Identification keys are included for the differentiation of species, subspecies, and varieties, as well as their morphological descriptions, geographic distribution, habitat, vernacular names, uses, illustrations, nomenclatural notes, and information about the studied specimens.

A revised assessment of Croton L. sect. Geiseleria (A. Gray) Baill. is provided. The section as now circumscribed includes 84 species ranging across warm areas of the Americas. A nuclear ITS phylogeny of 150 accessions from 83 species and a chloroplast trnL-F phylogeny of 89 accessions from 65 species were generated to confirm correct phylogenetic placement of the species and to determine if any species previously included in the section should now be excluded. Seven new species are described, and we present a taxonomic synopsis that lists all currently accepted species along with their synonyms, distributions, and pertinent comments. We also recognize four subsections within Croton sect. Geiseleria and list their corresponding species. Based on both morphological and molecular criteria, we now recognize C. lagunillae Croizat as a distinct species, rather than as a variety of C. guildingii Griseb. (now treated as C. suavis Kunth), and we treat C. ramillatus Croizat var. magniglandulifer V. W. Steinm. as a species, C. magniglandulifer (V. W. Steinm.) B. W. van Ee. We also exclude C. tetradenius Baill. from Croton sect. Geiseleria (A. Gray) Baill. along with related species such as C. pulegiodorus Baill. and C. leptobotryus Müll. Arg., which are either members of Croton sect. Adenophylli Griseb. or else may merit new sectional status. We also exclude C. waltherioides Urb., although it is not clear to which section of Croton it belongs.

We present an annotated checklist of the 14 species of Drypetes Vahl (Putranjivaceae) that occur in Liberia, as well as distribution maps of the country for each. Three species are new records for Liberia: D. floribunda (Müll. Arg.) Hutch., D. klainei Pierre ex Pax, and D. laciniata (Pax) Hutch. In addition, we describe a new species, D. liberica Quintanar & D. J. Harris, an understory shrub or small tree that is endemic to Liberia. Based on the specimens studied, we provide types for all names, including 14 newly selected lectotypes, in order to stabilize the nomenclature of the taxa involved. We also lectotypify one species, D. leonensis Pax, that for the moment we do not cite for Liberia, but the name has been the source of confusion with a species that does occur in the country.

Biscutella L. ser. Biscutella (= Biscutella ser. Lyratae Malin.) comprises mostly annual or short-lived perennial plants occurring in the Mediterranean basin and the Middle East, which exhibit some diagnostic floral features. Taxa in the series have considerable morphological plasticity, which is not well correlated with clear geographic or ecologic patterns. Traditional taxonomic accounts have focused on a number of vegetative and floral characters that have proved to be highly variable, a fact that contributed to taxonomic inflation mostly in northern Africa. A detailed study and re-evaluation of morphological characters, together with recent phylogenetic data based on concatenation of two plastid and one nuclear region sequence data, yielded the basis for a taxonomic reappraisal of the series. In this respect, a new comprehensive integrative taxonomic arrangement for Biscutella ser. Biscutella is presented in which 10 taxa are accepted, namely seven species and three additional varieties. The name B. eriocarpa DC. is reinterpreted and suggested to include the highest morphological variation found in northern Morocco. Its treatment here accepts two varieties, one of which is described as new (B. eriocarpa var. riphaea A. Vicente, M. Á. Alonso & M. B. Crespo). In addition, the circumscriptions of several species, such as B. boetica Boiss. & Reut., B. didyma L., B. lyrata L., and B. maritima Ten., are revisited. Nomenclatural types, synonymy, brief descriptions, cytogenetic data, conservation status, distribution maps, and identification keys are included for the accepted taxa, with seven lectotypes and one epitype being designated here.

Generic boundaries of the South American species Panicum longipedicellatum Swallen are explored and compared with allied genera of the tribe Paniceae. On the basis of morphological, anatomical, and molecular characters a new genus, Cnidochloa Zuloaga, is proposed. The phylogenetic position of the new genus within the Paniceae is evaluated.

Trans-Beringia taxa often present complex puzzles for taxonomists, a reflection of differing traditions and opinions, taxonomic approaches, and access to material from both sides of the Bering Strait. There is wide biological variation in perceived or circumscribed taxa whose populations are widespread within the regions and yet biogeographically isolated in Asia and/or America. The Claytonia arctica complex is one such example; it illustrates these issues well and has been dealt with by North American and Russian botanists in decidedly different ways. We reviewed specimens and examined the various taxonomic concepts of C. arctica through time and source publications. The relationships (alignments) among taxonomic concepts are presented in a graphical format. We found that much of the confusion related to C. arctica in Beringia stems from overlookingC. scammaniana Hultén sensu Hultén (1939), and placing too much emphasis on the woody caudex and perennation structures, during the creation of two taxonomic concepts: C. arctica Adams sensu Porsild and C. porsildii Jurtzev sensu Yurtsev. The C. arctica complex (in our current sense) is an evolutionary work in progress, resulting in partially differentiated races with much overlapping variability and intergradation of characters (particularly in C. scammaniana according to our current sense) that have not reached the level of stability (i.e., individuals may still intergrade freely) usually associated with the concept of species in other arctic lineages.