Decoding leaf micro- and macro-morphology: a path to effective particulate matter phytoremediation.

With the rapid expansion of urban areas and industries, particulate matter (PM) pollution has become a pressing global concern. Phytoremediation offers a sustainable solution to mitigate indoor and outdoor air pollution. Leaves, with their expansive surfaces, serve as primary PM receptors, playing a vital role in air quality improvement by retaining deposited PM. Retention of foliage PM relies on a dynamic equilibrium between accumulation and resuspension of PM, predominantly influenced by functional leaf traits. Both macro- and micro-morphological features, including leaf length, width, aspect ratio, surface roughness, petiole length, stomata, trichomes, cuticle, waxes, ridges, and grooves, significantly affect PM accumulation and retention. Among macro-morphometrical characters, broader, rough-surfaced leaves with shorter petioles are more efficient in PM accumulation than those with narrow-smoother surfaces having long petioles. Moreover, exposure to polluted environments can induce microstructural changes in leaves, further enhancing PM retention. Rather than focusing on a single trait, combining multiple effective traits may better optimize PM removal. Developing green spaces with plants possessing these traits not only enhances urban greenery but also maximizes their potential to reduce pollution and improve air quality.