Figure 1.

Conceptual representation of the optical properties of the nine (a–i) structural elements of leaves (typical bifacial leaves with various structural idiosyncrasies (a–h) and representative bamboo leaf (i)) included in the light module: (a) cuticle light reflectance, (b) epidermal cell light focusing, (c) non-glandular hair light reflectance and scattering, (d) gland light reflectance and scattering, (e) multiseriate sclerified hypodermis light scattering, (f) crystal or cystolith light scattering, (g) bundle sheath extension light scattering and path lengthening, (h) sclereid light transfer, and (i) bamboo’s fusoid cell. Five elements are superficial (a–e) and four elements are located in the mesophyll (f–i). The structural elements presented are highlighted in magenta in each drawing. In each structural element, arrows (red for photosynthetically active radiation (PAR) and black for ultraviolet radiation (UV)) show surface light reflectance, surface and mesophyll light scattering, and hypothesized light path lengthening. Light absorption phenomena (e.g., UV radiation absorption from epidermal cells in (a)) are omitted for clarity. The optical properties for bamboo fusoid cells (i) were not conceptualized due to the unavailability of data from the literature. Colour coding represents the four functional modules of leaves (light, gas exchange, water–nutrient, and defense–protection modules) and coloured rectangles under each drawing show all the functional modules in which each element participates.