Iris pseudacorus shows differences in traits between the native and non-native ranges
Iris pseudacorus (Iridaceae) is a widespread native species to the EPPO region and is recorded as an invasive alien plant species in Argentina, Canada, New Zealand, the USA and South Africa. In wetland habitats, it can have a negative impact on biodiversity and ecosystem services outcompeting native plants. It can alter the structure of the habitat including changing the abiotic and biotic dynamics. A study was conducted using seed of I. pseudacorus from its native (Belgium) and introduced (Argentina) range, to assess the variation in germination and early growth across the ranges. Seeds were collected from six sites in both Belgium and Argentina and germinated under controlled conditions with half of the seeds from each range exposed to cold stratification (≈ 4°C). The other half of the seeds were used as a control and stored at room temperature. The seeds were germinated in Petri dishes and subsequently planted in pots. Time to germination and plant growth parameters were measured. Overall, the percentage of germinated seeds was higher in seeds from Argentina. Both cold stratified and control seeds from Argentinian sites germinated rapidly whereas Belgian cold stratified seeds germinated faster than Belgian control seeds. Differences were also seen between the ranges in early growth responses with Belgian cold stratified seedlings showing high biomass though Argentinian seedlings showed higher biomass – particularly related to belowground structures. The results suggest that non-native populations have higher germination plasticity which can promote invasion in novel areas. Additionally, changes in early growth response suggests that the lower cold tolerance of Argentinian seed enables the population to invest more in growth.
Sources
Minuti G, Gervaszoni P, Glese C, Cabaňas A, Delange O, Cantarelli M, Nicolo R, Franceschini C, Stiers I, Sosa A, Coetzee J (2026) Cross-range comparisons reveal reduced dormancy and enhanced growth in alien Iris pseudacorus L. Not peer-reviewed. To be published in Biological Invasions. Research Square, https://doi.org/10.21203/rs.3.rs-8319498/v1