Leaf-scale refers to the small, flat plates that cover the surface of a plant leaf, serving as a protective layer against external factors. There are several synonyms for the term leaf-scale, including trichomes, cuticles, epidermal cells, stomata, and guard cells. Trichomes are tiny hairs or spines on the surface of a plant leaf that can provide protection against predators and UV radiation. Cuticles are the waxy layer that covers the leaf surface and helps to reduce water loss. Epidermal cells are the outermost layer of cells on the leaf surface. Stomata are small pores on the leaf surface that allow gas exchange, and guard cells are specialized cells that regulate the opening and closing of stomata.