Fig. 10.2-3. Transverse section of spurge stem (Euphorbia corallata). The cuticle on this epidermis is unusually thick, almost one-half the thickness of the lumen of the cell. Such thick cuticle typically occurs only on plants of very dry habitats (where it is advantageous in keeping water from evaporating from the plant) or of extremely wet ones (where it prevents the abundant rainwater from leaching nutrients out of the protoplasts). Notice that it is thinnest at the junctions between cells, thickest over the cell body: the epidermis cells themselves bulge outward, but the variation in cuticle thickness accentuates the roughness of the stem surface.