The Stalk

• The stalk consists of segments called joints.
• Each joint is made up of a node and an internode.
• The node is where the leaf attaches to the stalk and where the buds and root primordia are found.
• The joints at the base are short and internodes length gradually increases.
• The buds, located in the root band of the node, are embryonic shoots consisting of a miniature stalk with small leaves.
• The outer small leaves are in the form of scales. The outermost bud scale has the form of a hood.
• Normally, one bud is present on each node and they alternate between one sides of the stalk to the other.
• The root band also contains loosely defined rows of root primordia. Each primordium exhibits a dark centre, which is a root cap, and a light coloured "halo."
• When seed-cane is planted, each bud may form a primary shoot which bears secondary shoots called "tillers" may form from the underground buds on the primary shoot.

• All colors of the stalk derive from two basic pigments: the red color of anthocyanin and the green of chlorophyll. Yellow stalks indicate a relative lack of these pigments. The surface of the internode, with the exception of the growth ring, is more or less covered by wax.

• Where the internode is exposed to the elements, a black mold usually develops on the waxy surface.
• The top 1/3 contains many buds and a good supply of nutrients which makes it valuable as seed cane for planting while rest 2/3 has good sucrose content.
• A cross section of an internode shows, from the outside to the centre, the following tissues: epidermis, cortex or rind, and ground tissue with embedded vascular bundles. The epidermis is a single superficial layer of cells that exhibit different patterns which are variety dependent.

                                                                    

                                                                           Fig: The stalk of sugarcane

Generally, the patterns are formed by two cell types, the so-called long cells and short cells that alternate with one another.

• The cortex or rind consists of several layers of cells just inside the epidermis.
• The cells of the rind are thick-walled and lignified.
• The ground tissue contains the vascular bundles with the xylem and phloem.
• Xylem tissue conducts water and its dissolved minerals upward from the roots, and phloem conductive tissue transports plant-manufactured nutrients and products, for the most part, downward toward the roots.
• The vascular bundles are much smaller and more prevalent toward the periphery of the stalk.