Leaf micromorphology affects the particulate matter retention in herbaceous plants: An in situ interspecies comparison

Garden plants can absorb and retain atmospheric particles and are important for remediating environmental pollution. As an important biological constituent of urban landscape, herbaceous plants can provide ecosystem service such as particulate matter (PM) retention. However, the evaluation of this ecosystem service for herbaceous plants has been seldom made. The present study compared the PM retention capacity of four herbaceous plants commonly used for urban greening in North China—Liriope spicata (Thunb.) Lour., Lolium perenne L., Festuca elata Keng ex E.B.Alexeev, and Poa pratensis L. and explored the correlation between leaf micromorphological traits and PM retention using an in situ experiment. PM with different particle sizes, including PM_>10 (10–100 µm), PM₁₀ (2.5–10 µm), and PM_2.5 (<2.5 µm), were separately evaluated. We found that L. spicata had the greatest PM retention capacity for all particle sizes among the four species. Electron microscopy revealed that leaves with higher groove proportion, larger stomatal size and greater densities of stomata and trichome generally had higher PM retention capacity. The study showed the correlation between leaf micromorphology and PM absorption, providing a scientific basis for further quantitative studies on the ecosystem service of PM absorption provided by herbaceous plants.