Gypsum soils occur around the world, mainly in arid regions. These harsh environments promote unusual flora with high degrees of endemism. Mexico has extensive gypsum outcrops, but their flora has been poorly studied. However, the highest species richness and endemism are expected to be concentrated in Mexico’s northern dry regions. To promote the study of this flora and its conservation, we estimate how well sampled it is, quantify species richness, identify centers of endemism, and detect which gypsum outcrops lie within federal protected natural areas (PNA). We conducted exhaustive literature and herbaria reviews to generate a database of botanical records on gypsum soils. The total species and gypsophyte richness were calculated using cell grids. Centers of endemism were identified using the corrected weighted endemism index (CWE). We mapped the gypsum outcrops within PNA polygons. The most collected sites are Cuatro Ciénegas (Coahuila) and Santo Domingo Tonalá (Oaxaca), which also had the highest total species richness. Nevertheless, gypsophyte richness was higher in Cuatro Ciénegas and Nuevo León. The CWE identified seven gypsophyte centers of endemism. Mexico hosts the most diverse gypsophile flora in the world, despite having been only partially studied and collected. The regions with the highest species richness and endemism are unprotected.

Two well-defined new species of Iresine from Mexico are described based on character data covering vegetative and floral morphology, pollen, and sequences of plastid matK-trnK, trnL-F and rpl16 as well as nuclear ITS. We provide morphological and molecular descriptions, as well as a discussion on diagnostic characters and taxonomic affinities. Both species are distributed in cloud forests; I. borschii is known only from two collections in Veracruz, whereas I. sousae has been collected several times in Oaxaca and Chiapas. Both species are illustrated from herbarium specimens to facilitate their recognition. New field collections and observations are needed to improve our knowledge on the habitat and conservation status of these new species. Citation: Flores-Olvera H., Zumaya S. & Borsch T. 2016: Two new species of Iresine (Amaranthaceae: Gomphrenoideae) from Mexico supported by morphological and molecular characters. — Willdenowia 46: 165–174. doi: http://dx.doi.org/10.3372/wi.46.46113 Version of...

Plant recruitment interactions (i.e., what recruits under what) shape the composition, diversity, and structure of plant communities. Despite the huge body of knowledge on the mechanisms underlying recruitment interactions among species, we still know little about the structure of the recruitment networks emerging in ecological communities. Modeling and analyzing the community‐level structure of plant recruitment interactions as a complex network can provide relevant information on ecological and evolutionary processes acting both at the species and ecosystem levels. We report a data set containing 143 plant recruitment networks in 23 countries across five continents, including temperate and tropical ecosystems. Each network identifies the species under which another species recruits. All networks report the number of recruits (i.e., individuals) per species. The data set includes >850,000 recruiting individuals involved in 118,411 paired interactions among 3318 vascular plant species across the globe. The cover of canopy species and open ground is also provided. Three sampling protocols were used: (1) The Recruitment Network (RN) protocol (106 networks) focuses on interactions among established plants (“canopy species”) and plants in their early stages of recruitment (“recruit species”). A series of plots was delimited within a locality, and all the individuals recruiting and their canopy species were identified; (2) The paired Canopy‐Open (pCO) protocol (26 networks) consists in locating a potential canopy plant and identifying recruiting individuals under the canopy and in a nearby open space of the same area; (3) The Georeferenced plot (GP) protocol (11 networks) consists in using information from georeferenced individual plants in large plots to infer canopy‐recruit interactions. Some networks incorporate data for both herbs and woody species, whereas others focus exclusively on woody species. The location of each study site, geographical coordinates, country, locality, responsible author, sampling dates, sampling method, and life habits of both canopy and recruit species are provided. This database will allow researchers to test ecological, biogeographical, and evolutionary hypotheses related to plant recruitment interactions. There are no copyright restrictions on the data set; please cite this data paper when using these data in publications.

Plant–plant interactions are major determinants of the dynamics of terrestrial ecosystems. There is a long tradition in the study of these interactions, their mechanisms and their consequences using experimental, observational and theoretical approaches. Empirical studies overwhelmingly focus at the level of species pairs or small sets of species. Although empirical data on these interactions at the community level are scarce, such studies have gained pace in the last decade. Studying plant–plant interactions at the community level requires knowledge of which species interact with which others, so an ecological networks approach must be incorporated into the basic toolbox of plant community ecology. The concept of recruitment networks (RNs) provides an integrative framework and new insights for many topics in the field of plant community ecology. RNs synthesise the set of canopy–recruit interactions in a local plant assemblage. Canopy–recruit interactions describe which (“canopy”) species allow the recruitment of other species in their vicinity and how. Here we critically review basic concepts of ecological network theory as they apply to RNs. We use RecruitNet, a recently published worldwide data set of canopy–recruit interactions, to describe RN patterns emerging at the interaction, species, and community levels, and relate them to different abiotic gradients. Our results show that RNs can be sampled with high accuracy. The studies included in RecruitNet show a very high mean network completeness (95%), indicating that undetected canopy–recruit pairs must be few and occur very infrequently. Across 351,064 canopy–recruit pairs analysed, the effect of the interaction on recruitment was neutral in an average of 69% of the interactions per community, but the remaining interactions were positive (i.e. facilitative) five times more often than negative (i.e. competitive), and positive interactions had twice the strength of negative ones. Moreover, the frequency and strength of facilitation increases along a climatic aridity gradient worldwide, so the demography of plant communities is increasingly strongly dependent on facilitation as aridity increases. At network level, species can be ascribed to four functional types depending on their position in the network: core, satellite, strict transients and disturbance‐dependent transients. This functional structure can allow a rough estimation of which species are more likely to persist. In RecruitNet communities, this functional structure most often departs from random null model expectation and could allow on average the persistence of 77% of the species in a local community. The functional structure of RNs also varies along the aridity gradient, but differently in shrubland than in forest communities. This variation suggests an increase in the probability of species persistence with aridity in forests, while such probability remains roughly constant along the gradient in shrublands. The different functional structure of RNs between forests and shrublands could contribute to explaining their co‐occurrence as alternative stable states of the vegetation under the same climatic conditions. This review is not exhaustive of all the topics that can be addressed using the framework of RNs, but instead aims to present some of the interesting insights that it can bring to the field of plant community ecology.

Con el objetivo de contribuir al conocimiento florístico de la sierra El Pelado del municipio de Acatlán, Puebla, contenida en la Cuenca del Balsas, se realizó exploración de campo para recolectar especímenes botánicos que se identificaron con claves y herramientas taxonómicas y consulta de especialistas. La zona alberga 339 especies correspondientes a 225 géneros y 67 familias, de las cuales 102 especies son endémicas de México, 8 de ellas son propias de la cuenca del Balsas y 2, restringidas a Acatlán. Esta aportación agrega 36 especies y 3 géneros al listado florístico del estado de Puebla, se redescubrió a Jatropha riojae y se encontró una especie nueva del género Senna. Las familias con mayor riqueza de especies son Fabaceae, Asteraceae, Malvaceae, Cactaceae y Euphorbiaceae, mientras que los géneros más diversos son Bursera, Ipomoea, Tillandsia, Mimosa y Solanum. El tipo de vegetación dominante es la selva baja caducifolia (SBC), en la parte alta de la sierra se encuentra un bosque de encino y pastizal en el ecotono con la SBC. También se encontró vegetación secundaria producto del uso de suelo en agricultura. Las formas de vida más abundantes son las hierbas, seguidas de los arbustos y árboles. Se registraron los nombres comunes de 94 especies. Estos hallazgos sugieren la necesidad de intensificar la exploración botánica en el municipio para incrementar el conocimiento de la diversidad vegetal y la creación de un área natural protegida.