Effect of plant origin and phenological stage on the allelopathic activity of the invasive species <i>Oxalis pes?caprae</i>

PREMISE Invasion processes involve several mechanisms, some of which have received little attention. Allelopathy has been invoked as an invasion driver according to the novel weapon hypothesis (NWH), and polyploidization can also be important factor for success. However, very few studies addressed both topics together. We analyzed allelopathic effect polyploid Oxalis pes-caprae, invader in mediterranean-climate areas worldwide, from different origins ploidy levels (native: South Africa; invaded: Chile, Australia, California, Mediterranean Basin) on Lactuca sativa a model species. METHODS measured seed germination, initial plant height, aboveground belowground biomass grown field soil mixed with material or without activated carbon common garden experiment. performed experiment twice, when was vigorous senescent. RESULTS Vigorous plants tended reduce but senescent increased biomass, probably due increase nutrients provided by material. The highest traits occurred Iberian Peninsula. only happened especially strong Chile. CONCLUSIONS Although we did not find broad evidence NWH considering all together, reported differences potential depending their origin. These results highlight independent evolution invasiveness distant introduced ranges importance invaders’ origin testing hypotheses about drivers.