Figure 1

Flows of naturalised herbaceous species among the five Mediterranean regions. Only species introduced by the unintentional pathway have been considered. Each region is represented by a specifically coloured circle, the radius of which is proportional to the number of naturalised species it presents as recipient (see Table 1). The values inside the circle indicate the number of naturalised species that are native to that region, but naturalised in at least one of the other regions. The arrows represent the flows, and their thickness is proportional to the percentage of species that the donor region provides to the set of naturalised species of the recipient region. Black arrows indicate flows from regions other than the five Mediterranean ones. Positive or negative sign above the arrows respectively indicates major or minor flows rather than those expected following a randomness test of 999 simulations.