Page 54 – Epidermis

Page 54 – Epidermis

c. 1940

Fig. 47 .\tEpidermis. A. Surface views of the adaxial (a) and abaxial (b) epidermis of the basal portion of a half-grown leaf from a 6-months old plant to show the difference in the shape of the cells cells and the size of the silica bodies. Notice that only the longitudinal (i.e., radial) walls are undulated. X340. B, and C. the Surface views of the epidermis of the basal (i.e., non-chlorophyllaceous) region of a fully differentiated leaf: B, abaxial and C, adaxial, epidermis. Notice that the cells of the abaxial epidermis are elongated at right angles to the long axis of the leaf (in B) while those of the adaxial epidermis are elongated in the direction of the long axis (in C). Also notice the undulating and thickening longitudinal (i.e., radial) walls. X400. D. Surface view of the epidermal cells on the ridge of the abaxial side of the transition (i.e., sub-chlorophyllaceous) region of a fully developed leaf to show the undulation of both longitudinal (i.e., radial) and transverse walls, their thickening (notice the greater thickness of the longitudinal walls), the middle lamella and the silica bodies. The verrucose surface of the silica bodies is not indicated. X400. E. Surface view of the epidermal cells on the ridge of the abaxial side of the ehlorophyllaceous region of a fully developed leaf to show the thickness of the walls and the silica bodies. Notice how the undulated contour of the original cell wall (the middle lamella is not shown, but see D above) becomes smoothed out with the addition of successive thickening layers. Sometimes the silica body and the cell wall become connected by a process (wp) from the latter (see text). Arrow indicates direction of the long axis of the leaf in all drawings. X400.

Photographed by B. Krauss, circa 1940.