Technical Abstract: - Multiple introductions appear to be playing a prominent role to explain the success of biological invasions. One often cited mechanism is the prevention of a genetic bottleneck by the parallel introduction of several distinct genotypes, which in turn provides the heritable variation that can allow for local adaptation. Here we show that multiple introductions promoted the invasion of Aegilops triuncialis into serpentine habitats by providing differentially adapted genotypes. - Using microsatellite markers we investigated the genetic structure of multiple populations of Ae. triuncialis, invasive in serpentine soils in California, in comparison to native accession. In addition we determined flowering time and fitness on loam and serpentine for all samples. - The invasion involves three independent introductions. All Californian samples showed higher fitness on serpentine than on loam. The three independent introductions showed different pathways towards serpentine adaptation. The majority of Eurasian accessions showed a fitness decrease on serpentine soil but some individuals achieved high fitness due to similar flowering time phenology to California populations. - Our results suggests that the adaptations of invasive populations in California to serpentine may in fact be preadpatations, where multiple introductions provided the requisite variation to be sorted by the new habitat.