Sugarcane leaf: A cross sectional view
- The leaf of the sugarcane plant is divided into two parts: sheath and blade, separated by a blade joint.
- The sheath, as its name implies, completely sheaths the stalk, extending over at least one complete internode.
- The leaves are usually attached alternately to the nodes, thus forming two ranks on opposite sides.
- The mature sugarcane plant has an average total upper leaf surface of about 0.5 square meter and the number of green leaves per stalk is around ten, depending on variety and growing conditions.
- A cross-section through the leaf blade would show three principal tissues:
- Epidermis: the epidermal cells protect the underlying tissues from injury and drying, the epidermis contains stomata for controlling the exchange of gases
- Mesophyll: the mesophyll, or middle leaf tissue, contains the cells that perform most of the photosynthesis
- and veins or fibrovascular bundles: The fibrovascular bundles contain the xylem and phloem elements which conduct water and nutrients to and from the leaves
In addition to the above, there can be found other fibrous tissue for aiding in shaping and mechanically strengthening the leaves.
- The blade joint is where two wedge-shaped areas called "dewlaps" are found
- The color, size, and shape of the dewlaps on a mature plant are more or less characteristic of a variety.
- The "top visible dewlap" leaf is a diagnostic tissue that is frequently used in nutritional studies.
- The leaf sheath is similar in structure and function to the leaf blade.
- It is slightly simpler, however, in that it lacks some of the more specialized cells of the leaf blade.
- The ligule is a membranous appendage inside of the sheath which separates the sheath from the leaf blade.
- It is a slightly asymmetric organ whose color, size, and shape are age and variety dependent.
- The auricles, as their name implies, are ear-shaped appendages located at the upper part of the sheath margin.
- Not all sheath margins have auricles.
- Leaf pubescence, or the covering of the various leaf parts with short hairs, is also variety and age dependent.
- Pubescence is not found on the leaf blade of commercial varieties, but does exist in sugarcane germplasm.
- Sheath pubescence can be used to identify plants.
Submitted by kamini on Tue, 31/03/2009 - 17:12