Herbaceous Plants as a Phytoremediation Tool in Urban Areas: A Review

Rising global temperatures, increasing frequency and intensity of extreme climatic events, with associated growth of agricultural land use and urban expansion, represent critical drivers of biodiversity loss. Within this framework, urban areas are particularly vulnerable due to environmental stressors such as the heat-island phenomenon, soil sealing and depletion, and the accumulation of heavy metals and other pollutants. Recent sustainability-oriented urban policies recognize the strategic role of green infrastructures in mitigating these impacts by delivering essential ecosystem services, including phytoremediation. Here, the focus on herbaceous plants allows the selection of species with short life cycles and high colonization rates in marginal or disturbed urban habitats (e.g., roadside verges, compacted soils, and limited-volume planting areas). Therefore, the present review systematically examines herbaceous plant species with documented phytoremediation capabilities, focusing on Mediterranean native taxa evaluated under urban or peri-urban conditions. A total of 29 species met the selection criteria: taxonomically, Asteraceae represented the most frequent family (35%), followed by Fabaceae (21%), Brassicaceae, and Poaceae (each accounting for 10%). From a functional-trait perspective, hemicryptophytes dominated the dataset (66%), followed by therophytes (31%). Of the selected taxa, 55% primarily exhibited phytoextraction, 14% showed phytostabilization, and 31% demonstrated dual functionality, through combined extraction and stabilization pathways. These traits, combined with ecological adaptability to Mediterranean climatic regimes, support their application in Mediterranean urban environments.