INaturalist defines itself as an “online social network of people sharing biodiversity information to help each other learn about nature” and it is likely one of the largest citizen science web portals in the world, as every year millions of observations across thousands of species are gathered and collectively compiled by an engaged community of nearly 3 million users (November 2023). The strengths and potentialities that explain the success of the platform are reviewed and include, among others, its usability and low technical requirements, immediacy, open-access, the possibility of interacting with other users, artificial-intelligence-aided identification, versatility and automatic incorporation of the validated records to GBIF. iNaturalist has, however, features that scientists need to carefully consider when using it for their research, making sure that the quality of observations does not limit or hinder its usefulness in plant research. While these are identified (e.g., the lack of representative photographs for many observations or the relatively frequent identification errors), we provide some suggestions to overcome them and, by doing so, improve the use and add value to iNaturalist for plant research.

Invasive alien species are currently considered one of the main threats to global biodiversity. One of the most rapidly expanding invasive plants in recent times is Kalanchoe × houghtonii (Crassulaceae), an artificial hybrid created in the 1930s in the United States by experimental crossings between K. daigremontiana and K. tubiflora, two species endemic to Madagascar. Thanks to its large colonizing capacity (mainly derived from the production of asexual plantlets), K. × houghtonii soon escaped from cultivation and quickly spread in many parts of the world. However, its actual range is not well known due to the lack of a formal description until recent times (2006) and its strong morphological resemblance with one of its parentals (K. daigremontiana). The present study was aimed, in the first instance, to delimit the present distribution area of K. × houghtonii at the global scale by gathering and validating all its occurrences and to track its colonization history. Currently, K. × houghtonii can be found on all continents except Antarctica, although it did not reach a global distribution until the 2000s. Its potential distribution, estimated with MaxEnt modelling software, is mainly centered in subtropical regions, from 20° to 40° of both northern and southern latitudes, mostly in areas with a high anthropogenic activity. Unexpectedly, concomitant to a poleward migration, future niche models suggest a considerable reduction of its range by up to one-third compared to the present, which might be related with the Crassulaceaean Acid Metabolism (CAM) of K. × houghtonii. Further research may shed light as to whether a decrease in potential habitats constitutes a general pattern for Crassulaceae and CAM plants.

The genus Kalanchoe, mostly indigenous from Madagascar and Tropical Africa, is widely traded for ornamental value. In this study, we provided an updated list of wild and cultivated Kalanchoe taxa in Ecuador; we analyzed the temporal–spatial pattern of their records, and we categorized the invasion status for each taxon and its environment preferences. The records of any taxa belonging to this genus were compiled from an extensive search using various information sources. Our results confirmed the presence of 16 taxa of Kalanchoe in the country. Seven species and a hybrid were detected in the wild. Kalanchoe densiflora, K. laxiflora, K. pinnata, K. tubiflora, and K. ×houghtonii were categorized as invasive. We detected invasive records of some of these plants in protected areas. Almost all taxa had at least one record as cultivated, suggesting that the invasion pathway is ornamental trade. Kalanchoe pinnata individuals in the wild were recorded in the four biogeographic regions of Ecuador, which could be associated with the wide range of precipitations and temperatures in which the species may dwell. Our study highlights the importance of reducing the ornamental value and limiting the use of Kalanchoe taxa with invasive potential in horticulture and promoting, instead, the use of indigenous species.

In this study, we provide a comprehensive and updated inventory of the non-native vascular flora of continental Ecuador and analyze its key biogeographic and ecological attributes to inform biological invasion management. We recorded 486 non-native wild plant taxa, 52% of which are naturalized and 48% casual. This inventory was primarily based on secondary data (published literature, scientific reports, and online databases) and enriched through fieldwork and expert consultations. It includes information on taxonomy, life form, lifespan, origin, first year of record, and spatial-temporal distribution. The most represented families were Poaceae (16%), Asteraceae (10%), and Fabaceae (9%). About 60% of the taxa originated from Asia and/or Africa, and 67% are herbs. The earliest introductions date back to the late 18^th century, with an exponential increase beginning in ca. 1915. Only 13% of the taxa have a minimum residence time exceeding 125 years. The Andes accounted for the highest number of taxa (93%, including taxa shared with other regions). Nearly 80% of the non-native taxa have documented uses, most commonly ornamental (42%) and medicinal (38%). Naturalized taxa tended to have longer residence times and more frequently reported uses than casual ones, suggesting these traits may influence naturalization likelihood. Due to limited systematic sampling across the country, particularly outside the Central Andes, some spatial bias may exist. However, the integration of citizen science-derived data, a methodological innovation in our study, proved to be a promising approach for addressing knowledge gaps and improving detection efforts in regions with limited research capacity. Our findings offer a foundation for advancing the management of biological invasions in Ecuador through early detection, rapid response (EDRR), and species prioritization. Finally, we provide a practical, adaptable and replicable framework, based on citizen science and appropriate statistical analyses, for developing national inventories of non-native plant species in data-deficient countries.

Cities are often hotspots for biological invasions, showing much higher percentages of alien species than non-urbanized settings. The reasons are multiple and are mostly related to two main factors: their heterogeneous, highly disturbed habitats and their many gateways that allow alien species introduction (e.g., airports, roads, train stations, or gardens). In addition to being a sink of biological invasions, cities can also be a source of the spread of alien species into surrounding landscapes, which adds further complexity to this issue. Herein, we are presenting the results of a five-year survey of the alien flora of Montjuïc, the largest urban hill in Barcelona (Spain). In just about 3.4 km², we recorded up to 247 alien plant taxa, a figure much higher than those of many other Mediterranean cities and which clearly points to the role of Montjuïc as a hotspot for alien plants. The comparison with the alien flora of its surrounding region (coastal Catalonia) suggests that the alien flora of Montjuïc would have become enriched through many immigration episodes from close geographic areas. The hill, however, would have also acted as a source of the spread of alien plants, and indeed, some species have not been detected yet beyond the confines of Montjuïc. This study aims to be a key tool to ensure early detection and also to develop appropriate management and/or eradication actions.