Background and aims – Tropical dry forests are among the most threatened ecosystems on Earth, and in the Cauca River Geographic Valley of Colombia only about 500 ha remain. Where two sites share few species, either each holds a different set of taxa (turnover) or the poorer is a reduced version of the richer (nestedness), and these two components call for opposite conservation responses. We asked which one governs this flora, whether the answer depends on the method, and which fragment attributes predict each component. Material and methods – We analysed the presence and absence of 915 vascular plant taxa across 35 fragments. Compositional difference was separated into replacement and richness-difference contributions under two frameworks. Each component was related to the fragment’s position, elevation and area by constrained ordination, and tested for an increase with the geographic distance. Fragments were also ranked by the taxa they add to a growing selection. Key results – Compositional difference was very high (multi-site Jaccard = 0.977). Replacement dominated under both frameworks, though its estimated share differed (98% and 60%). Constrained ordination showed position and elevation to structure replacement, whereas area was unrelated to it and predicted only the richness-difference component. Dissimilarity increased with distance (Mantel r = 0.238, p < 0.001), but no component carried that signal under both frameworks. Two fragments held 54% of the flora, 11 reached 90% and 31 out of 35 carried a complete representation of all taxa. Conclusion – These forest fragments are not impoverished copies of one another, but distinct assemblages, each holding taxa the others lack. The area governs how many taxa a fragment holds, not which ones, so protecting the largest fragment would capture only part of the flora. That the spatial signal could not be attributed to one component under both frameworks is a caution for a literature in which such attributions rest on a single partition.
Background and aims – We present the first comprehensive checklist of North American gypsophiles (plants restricted or nearly restricted to gypsum soils) to encourage the further exploration of gypsum exposures, promote systematic studies, and raise awareness about the potential need of conservation measures for these ecologically and evolutionary unique species. Material and methods – The checklist was based on a historical literature search, herbarium specimens, and fieldwork. We estimated an Aridity Index for the gypsum localities of all occurrences, taxa description over time, growth form, generic diversity within families as compared to global patterns, and conservation status. Key results – We recognize 287 taxa as gypsophiles, which occur from Montana, USA to southern Mexico, including 282 angiosperm taxa, 3 ferns, one gymnosperm, and one lycophyte. Herbaria and literature review retrieved 3,528 records for gypsophile taxa. The gypsum localities from these records were classified from arid to humid, with most being arid or semi-arid. The most diverse families were Asteraceae (77 taxa), Brassicaceae (14), Loasaceae/Nyctaginaceae (13), and Cactaceae/Namaceae (11). The most diverse genera were Mentzelia / Nama / Nerisyrenia (11), Phacelia / Pinguicula (9), and Drymaria / Gaillardia (8). Most gypsophile taxa were classified as perennial herbs (207) or shrubs (38), but annual herbs (17) and one tree-like species were also recorded. Only 45 taxa were found to be protected at any level. Conclusion – North America has the most diverse gypsophile flora yet known globally. It is composed of a wide phylogenetic diversity including many growth forms and biomes, ranging from xeric shrublands to grasslands, coniferous forests, and tropical forests. Few gypsophile taxa have legal protections, and additional studies are clearly needed to assess their conservation risk. This first comprehensive checklist, while subject to change, will serve as a foundation for future research.
Background and aims – Alternanthera is one of the largest genera in Amaranthaceae, with the primary distribution in the Americas. The identification of some species, including those occurring as alien noxious weeds in the Old World, is challenging because of unstable taxonomy and nomenclature. In addition, their means and history of introduction remain poorly understood. Here, we revise the alien species of Alternanthera in the Arabian Peninsula, providing notes on their morphology, distribution, nomenclature, and dispersal facilities. Material and methods – We analysed type specimens, vegetative, floral and fruit characters, introduction history, and occurrences of four species of the genus in the Arabian Peninsula. Key results – Alternanthera ficoidea is reported for the first time from the Arabian Peninsula, and A. sessilis is newly recorded in the United Arab Emirates. The history and means of the species introduction are discussed. The turbulent nomenclatural history of A. ficoidea and A. tenella is reviewed to resolve the current confusion in their European records, and we propose that the latter name should unambiguously be considered as a synonym of A. ficoidea . The original spelling of Telanthera “ bettzickiana ” and A. “ bettzickiana ” are researched, and the species epithet is corrected to “ bettzichiana ”. A lectotype is designated for A. achyranthes , the generic type of Alternanthera . Detailed morphological descriptions of the propagules of Alternanthera are provided, and their role in the dispersal process are discussed. Conclusion – We noted a recent expansion of Alternanthera ficoidea , A. pungens , and A. sessilis in natural and anthropogenically disturbed plant communities of the Arabian Peninsula, especially across the coastlines of the Arabian Sea and Red Sea, and in foothills of the Sarawat Mountains. Their spread occurs through both vegetative and sexual means of dispersal. Our examination of morphological characters reveals a distinct role of the perianth and pericarp in the propagule dispersal of these species.
The article on the environmental drivers of the distribution of Ragala ucuquirana-branca (Sapotaceae) across the Amazon Basin, published in Plant Ecology and Evolution 159(2), contained an unfortunate error (Cunha et al. 2026). Earlier versions of Figs 3, 5, 6, and 7, prepared before the manuscript was revised during peer review, were inadvertently published instead of the revised versions. As a result, these figures do not fully match the text and figure captions of the article. The correct figures and their captions are presented here.
Background and aims – Triniochloa is a genus endemic to the Americas. Currently, there are six described species, four of which are Mexican endemics. In this study, we present a description, distribution map, and photographs of a new species of Triniochloa endemic to Jalisco, Mexico and a phylogenetic hypothesis based on a nuclear DNA marker. Material and methods – This study was based on a phylogenetic analysis of nuclear ITS, fieldwork, and a review of literature and herbarium specimens. The specimens collected were analysed and photographed during fieldwork. The conservation assessment is based on spatial analysis, following the IUCN guidelines and criteria. Key results – The molecular phylogenetic hypothesis recovered the new Triniochloa species as sister to T. talpensis . Morphologically, T. villalpandoana sp. nov. differs from T. laxa and T. talpensis by its longer spikelets, glumes, and lemma. It is endemic to Cerro de los Bailadores, Zapopan, Jalisco. This mountain lies just 20 km in a straight line to the northwest of the Guadalajara metropolitan area. The vegetation is an oak-pine forest that grows in rocky, humid ravines at elevations from 1640 to 2000 m. According to our conservation assessment, this species should be considered Critically Endangered. Conclusion – The discovery of Triniochloa villalpandoana sp. nov. adds a seventh species to this American endemic genus. Morphologically, the new taxon stands out from its closest relatives, T. laxa and T. talpensis , by its substantially larger spikelets, glumes, and lemmas, a combination of traits that supports its recognition as a distinct species.
