Eryngium maritimum L. is considered a key species in dunes of the western Mediterranean. Although Northern European populations are endangered, the Mediterranean populations show a good conservation status, despite a lack of studies of the reproductive requirements and strategies of this species. This study aims to analyse the reproductive biology of a population of E. maritimum in the western Mediterranean (Balearic Islands, Spain), specifically focusing on differences in morphometric and reproductive traits among inflorescence orders. Capitulum size, number of flowers, fruit set and seed set were analysed to evaluate the morphological and reproductive differences among inflorescence orders. The association between subterranean development and investment in reproductive structures was also studied along the dune location. Breeding system was analysed, evaluating self‐pollination capacity at capitulum level and the pollen/ovary ratio. Finally, floral visitors were assessed. Morphometric and reproductive traits showed a decline in size and production from early to subsequent inflorescence orders. A correlation between width of stem base (caudex) and number of reproductive structures was observed, whereas seashore distance did not affect the reproductive development. Flowering occurred during summer, from May until late July, while fructification took place from the middle of August until the last days of September. Pollinator exclusion treatments induced a fruit and seed set decline. Twenty‐one species of floral visitor were found. First and second inflorescence orders contributed to the generation of seeds, displaying high fruit and seed production, while other inflorescence orders seemed to attract pollinators. Reproductive and non‐reproductive development could depend on the capacity to reallocate resources from underground to aerial structures, which seemed to be superior in samples with highly developed caudices. In the studied population, inner areas closest to the seashore showed a delay in anthesis, which could be related to microclimate differences along the coast‐to‐inland gradient. Pollination is strongly entomophilous and showed low levels of self‐compatibility at capitulum level. Considering these results, for habitat conservation the reported microclimate diversity should be taken into consideration, with a focus on conservation of the pollinator populations

Germination is considered as one of the most crucial steps in a plant’s lifetime. The germination of Eryngium maritimum, a dune species located across all European coasts, has been extensively analysed in Northern populations, where it is considered a locally endangered species. However, less attention has been given to southern populations, where the knowledge about the germination of the species is very limited. The main objective of the present study was to analyse the effect of cold stratification in one Mediterranean and one Atlantic population of the species, as well as to compare the potential variation of seed dormancy among a latitudinal gradient in European populations based on current literature. Seeds collected from Mallorca (Mediterranean, Spain) and Asturias (Atlantic, Spain) were germinated at different temperatures and cold stratification periods ranging from 4 to 20 weeks. These results were merged with the results of previous studies to test the potential effect of latitude and climatic variables in germination. Although the optimal incubation temperature was 10 ºC, the highest final germination percentages (up to 96%) was obtained in both populations combining specific cold stratification periods (5 ºC) and constant incubation temperatures (15–20 ºC). Atlantic seeds needed longer cold stratification times to reach high germination percentages compared with Mediterranean seeds. Apart from the stratification response, significant differences in viability and in germination were observed between the Atlantic and the Mediterranean populations. Considering data from previous studies in the analysis, the results suggest that there is a potential effect of latitude in the ecological germination requirements, by which the higher the latitude, the longer the cold stratification period required to germinate, with a correlation with the mean annual temperature. These results suggests that two factors, modulation of dormancy relating to adaptative or maternal effects and viability, govern the germination of the species.

Allochthonous plant species are considered among the main environmental issues worldwide, being especially accused in the Mediterranean basin. The present study aims to update Balearic Alien Flora and discuss its time and spatial variation and invasiveness. Information regarding allochthonous plant records of the Balearic Islands were gathered and analysed based on published checklists and online databases. For each species several general traits were assigned based on previous references to characterise the alien Balearic Flora. Records of allochthonous species between 1827 and 2023 indicate that Alien Balearic Flora is composed of 624 taxa recorded unevenly among islands, with lower records in smaller islands. Alien flora is mainly composed of therophytes and phanerophytes being held mainly in human related habitats. Introduction pathway is mainly ornamental, with over 50% of taxa entering through gardening and horticultural practices. Main biogeographical origins are American, Mediterranean, Euroasiatic and Cape origins. Invasive status of Balearic alien flora shows that 44% of all taxa can be regarded as casual, while 35% are naturalised, and 17% can be considered invasive, being the latter increased in smaller islands. Time variations trends starting mainly in the 70 s and predictive models show that alien species increase exponentially, being the most represented taxa from synanthropic habitats, introduced as ornamentals, lianas, phanerophytes and therophytes from Cactaceae, Asteraceae and Leguminosae families. The results of the present study can serve as a model to facilitate the scientifically informed decision making and management of plant invasions both in the Balearic Islands and other continental insular systems and Mediterranean regions.

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