Fig. 65.—Transverse section of a portion of the leaf of Panicum fluitans. × 120
1. Motor cells; 2. stomata; 3. sclerenchyma; 4. chlorophyllous layer.
As regards size, the epidermal cells overlying the sclerenchyma are small and those lying over parenchyma are larger. Amongst the larger cells some may be motor-cells. The stomata occur in regular rows between the vascular bundles and they are quite characteristic of grasses. They are more or less similar in structure in all grasses. In the leaves of many grasses stomata are found in both the upper and the lower epidermis and they are confined to the lower epidermis in a few grasses only.
The motor-cells vary very much both as regards their shape and position. In some leaves as in the leaves of the grass Panicum flavidum the motor-cells are confined to the midrib on the upper surface.
The epidermal cells of this leaf are large and uniformly round. (See figs. 66 and 67.)
Fig. 66.—Transverse section of a leaf of Panicum flavidum. × 20
1. Vascular bundle; 2. sclerenchyma; 3. motor-cells.