Fig. 47.—Transverse section of the stele portion of the root of Andropogon Sorghum. × 150
Co. Cortex; en. endodermis; pe. pericycle; ph. phloëm; pr. protoxylem; xy. xylem vessel.
Fig. 48.—A portion of the transverse section of the leaf of Panicum javanicum. × 100
Ep. c. An ordinary epidermal cell; st. stomata; sc. sclerenchyma; ph. phloëm; chl c. chlorenchyma; m. motor cells; xy. xylem.
For a detailed study of the structure of the leaves of grasses the leaf of the grass Panicum javanicum may be chosen. In a transverse section of this leaf, the vascular bundles are very conspicuous. The larger bundles are normal in every way, while in the smaller ones the xylem elements are considerably reduced. Around every one of the vascular bundles there is a single row of large cells containing large chlorophyll grains (the chlorophyllous layer). In a well developed large vascular bundle the chlorophyllous layer is open below just close to the sclerenchymatous band. On both sides of the larger vascular bundle there are bands of sclerenchyma. In the case of smaller bundles some are strengthened by sclerenchyma on the lower side and others have none. The spaces between the bundles are occupied by thin-walled parenchymatous cells containing small chlorophyll grains.
Fig. 49.—Upper epidermis of the leaf of Panicum javanicum. × 300