The Impact of Life History Traits and Defensive Abilities on the Invasiveness of Ulex europaeus L.

Ulex europaeus L. has been introduced into many countries as an ornamental and hedgerow plant, and it often escapes its intended location, establishing dense, feral thickets. These thickets threaten the structure and function of native flora and fauna in areas where the plant has been introduced. Because of its invasive nature, U. europaeus is considered one of the world’s 100 worst alien invasive species. It exhibits rapid growth, and high biomass accumulation with a high nitrogen fixation ability. Its flowering phenology depends on local conditions and population. It produces a large number of viable seeds and establishes extensive seed banks. These seeds remain viable for a long time due to physical dormancy. Ulex europaeus produces elaiosomes on the seed surface that are likely used solely for seed dispersal by ants. Ulex europaeus has a high level of genetic diversity due to its allohexaploid chromosome sets. This allows the plant to adapt to different habitats and tolerate various climate conditions. It can survive in areas with limited sunlight beneath tall plant canopies. Its shade tolerance surpasses that of other shrub species. Ulex europaeus produces several compounds, including quinolizidine alkaloids, monoterpenes, flavonoids, and cinnamic acid derivatives. These compounds play a role in defensive responses to biotic stressors, including pathogen infections, herbivorous insects, and neighboring plants competing for resources. These life history traits and defensive abilities may contribute to the expansion of U. europaeus populations into new habitats, enabling the plant to thrive as an invasive species. This is the first study to examine the invasiveness of U. europaeus in terms of its growth, reproduction, ability to adapt to different conditions, and defensive responses to biotic stressors.