Alternative application of Helichrysum species: Plants suitable for phytoremediation and urban horticulture systems

Helichrysum species are widely recognized for their ecological resilience, ornamental value, and production of essential oils (EOs), which are extensively used in the cosmetic and pharmaceutical industries. Native to arid and Mediterranean environments, they are inherently tolerant of drought, high temperatures, and nutrient-poor soils, traits that make them suitable for both phytoremediation and urban horticulture systems such as green roofs and walls. Studies have shown that H. candolleanum , H. italicum , H. microphyllum subsp. tyrrhenicum , H. oligocephalum , H. splendidum , and H. stoechas are promising candidates for the phytoremediation of heavy metals and hydrocarbon-contaminated soils. Ornamental appeal and stress tolerance also position Helichrysum as an ideal candidate for incorporation into green roofs and walls, mitigating the effects of climate change in urban areas. Among Mediterranean xeropytes, H. italicum , H. luteoalbum , H. orientale , H. stoechas , and H. thianschanicum , show considerable potential for thriving on urban horticulture systems. Such systems benefit from species with low maintenance requirements, intermittent irrigation tolerance, and long-lasting visual impact, all of which characterize Helichrysum species. Importantly, heavy metals do not transfer to the EO during distillation, allowing the production of metal-free EOs that are safe for human health and environmentally sustainable. This dual role provides ecosystem services through pollution mitigation and climate regulation while generating valuable EOs. This review is to explore these alternative uses of Helichrysum species, emphasizing future research directions that integrate ecological, economic, and design perspectives.