Question: Do specific environmental conditions affect the performance and growth dynamics of one of the most invasive taxa (Carpobrotus aff. acinaciformis) on Mediterranean islands?

Location: Four populations located on Mallorca, Spain.

Methods: We monitored growth rates of main and lateral shoots of this stoloniferous plant for over two years (2002–2003), comparing two habitats (rocky coast vs. coastal dune) and two different light conditions (sun vs. shade). In one population of each habitat type, we estimated electron transport rate and the level of plant stress (maximal photochemical efficiency Fv/Fm) by means of chlorophyll fluorescence.

Results: Main shoots of Carpobrotus grew at similar rates at all sites, regardless habitat type. However, growth rate of lateral shoots was greater in shaded plants than in those exposed to sunlight. Its high phenotypic plasticity, expressed in different allocation patterns in sun and shade individuals, and its clonal growth which promotes the continuous search of available resources, contributed to a good growth and photochemical efficiency of Carpobrotus in the relatively moderate shade of the understories of Mediterranean shrublands and woodlands. Each main shoot of a Carpobrotus clone (which can have several dozens main shoots) grows ca. 40 cm per year, which explains its vigorous habitat colonization capacity.

Conclusion: The highly plastic morphological response to different light regimes of this taxon contributes to a rapid colonization of heterogeneous coastal Mediterranean environments spreading well beyond the open sand dune systems where it has been often reported.

Nomenclature: Tutin et al. (1964–1980).