Reservoirs of Biodiversity: Gardens and Parks in Portugal Show High Diversity of Ivy Species

Urban parks and gardens are important in multiple ways, but they are often mostly made of exotic species with little biodiversity value. Surveys conducted in public and private gardens and parks across diverse Portuguese cities reveal a surprisingly high level of ivy species diversity, even when there is no apparent ornamental value in growing multiple species. The analysis of 499 samples from Mainland Portugal, Azores, and Madeira shows that in Madeira, the endemic <i>H. maderensis</i> co-occurs with exotic species; in Mainland Portugal, <i>H. hibernica</i> is more common in the centre and north (49% of samples) and <i>H. iberica</i> in the south (50% of samples), following their distribution in nature, but co-occur with exotic species (mostly <i>H. helix</i>, <i>H. algeriensis</i>, <i>H. maroccana</i>, and <i>H. canariensis</i>). Often, different species are cultivated side by side in the same garden, thus depicting these gardens as hidden reservoirs of biodiversity and, simultaneously, as potential sources for biological invasion.