Fig. 3.4-1. Transverse section of leaf of Peucephyllum (no common name). The layer of large round cells is the epidermis, a type of boundary parenchyma. The thick, red-stained layer is the cuticle, composed of the water-proof material cutin. In this species, as in most, epidermis cells secrete cutin mostly to their outer wall, not the inner one. There is some deposition on the outer parts of the radial walls also. Because these epidermis cells have thin primary walls, they are parenchyma cells. The columnar cells in the lower half of the micrograph are palisade parenchyma cells, filled with red-stained chloroplasts. The two small cells with red contents in the center of the epidermis are the two guard cells on either side of a stomatal pore. Other than the stomatal pore, there are no intercellular spaces between epidermis cells.