The internal anatomy of the stem of the rice plant reveals an
                amazing world full of beautiful design, intricate parts, and complex
                systems.  With the aid of chemical stains, powerful microscopes, and
                polarizing filters, the following pictures are designed to demonstrate
                not only the anatomical and functional parts of the stem, but also the
                beauty in the microscopic world of the rice plant.
                This stem page will also show the variations in cross-sections of
                the stem, from the internodal region to below the node to the node
                and then through the panicle.
 
 

 

  An understanding of the anatomy of a basic cross section (x.s.) of the stem is an important foundation for following the terminology throughout the rest of the stem. Take a close look at the labeled diagram below of the basic anatomical features of the stem. The following sections and pictures go in depth on each of the separate tissue systems.
 

 
 

  
 
 
  

 
 
 Close-ups of the internal anatomical features of the rice stem according to their tissue systems:
 
 
 
 
DERMAL TISSUE SYSTEM:
 

Below is a magnified cross-section of the outermost region of the stem with the tissues and cells labeled.
Only the cuticle and the epidermal tissue comprise the DERMAL TISSUE SYSTEM.  The other regions are labeled for a better understanding of the outer components of the stem.
 

 
 

 
 
 
GROUND TISSUE SYSTEM:
 

Below are pictures depicting the different regions of the ground tissue system, including the 1)chlorenchyma tissue, the 2) storage parenchyma cells and their contents, and the 3) aerenchymous center of the stem.

 
       1) CHLORENCHYMA TISSUE:  Storage parenchyma cells specified for containing chloroplasts.  The chloroplasts utilize sunlight as energy for metabolizing carbon dioxide and water for the production of sugars (oxygen as a waste product).  The chloroplasts are what give the stem its green appearance.  Notice in the picture below, that the cortical region of the stem (from the vascular bundles up to the fibrous layer) does not always contain just chlorenchyma tissue.  The chlorenchyma tissue is primarily toward the outermost portion of the cortex.
 

  
 
 
 
  

       
            2) STORAGE PARENCHYMA TISSUE:  These parenchyma cells specialize is storing contents as energy in the form of starch and lipids, as ergastic substances in the form of crystals, and many other substances.  The following pictures are of parenchyma cells as wells as some detail on starch as the stored substance.
 
 

 
 
Starch as a stored stubstance:
 
 
 
           
 
 

            3) AERENCHYMOUS CENTER:  The aerenchymous center can be described as the hollow pith of the stem, although near the nodal regions, the center becomes filled with aerenchyma tissue.  This tissue, although it was not sectioned for examination, is most likely branched parenchyma cells.  The branch parenchyma cells are also the typical tissue comprising the diaphragm found in the hollow pith. The aerenchymous center functions primarily as an air channel for gases to be transported from the aerial plant parts down to the water-submerged regions of the plant.  This demonstrates a design perfectly fit for the environmental needs of the plant.
 

 
 
 
 
 [Link to top of page] [Link to tissue systems]
 
VASCULAR TISSUE SYSTEM:

The vascular tissue system itself is comprised of several different tissues with complex functions.  There will be a description and pictures for the 1)phloem tissue and the 2) xylem tissue in the VASCULAR TISSUE SYSTEM.
 
           
            1) PHLOEM TISSUE:  The phloem tissue is comprised of phloic fibers, sieve tube members, and companion cells.  The companion cells are extrodinarily distinct in the phloic tissue.  Take a look at the picture below to see the distinct "big cell, little cell" relationship.  The phloic fibers are found primarily above the phloem, although the outer edge of the rice stem is known to sometimes have a continuous ring of fiber cells just below the epidermis consisting of phloic fibers (by definition) as well as "other" fibrous schlerenchyma tissue.

                    REALLY COOL PICTURE THE COMPUTER LOST
 
 
 
 
            2) XYLEM TISSUE:  The xylem tissue is comprised of xylary fibers, protozylem vessel members, metaxylem vessel members, and xylem parenchyma cells.  The following picture shows each of these cells.  The primary function of the vessel members is to transport water and solutes, such as minerals and ions.
 
  
Below are close-ups of the protoxylem vessel members:
 
 
 
 
THAT IS ALL FOR THE BASIC INTERNAL ANATOMY OF THE STEM.
 
 [Link to top of page] [Link to tissue systems]
   
 
VARIATIONS IN CROSS SECTIONS OF THE STEM:
First of all, it is important to take a look at a MEDIAL LONGITUDINAL SECTION OF THE STEM.
Below is a picture of the internal anatomy of the nodal region of the stem.  The diaphragm and the air channel can be described as part of the arenchymous center.
 
 
 Now, take a look at the cross sections of the stem in both the nodal region, just below the panicle and through the panicle.  Take note of how the anatomy of the stem changes, as vascular bundle distribution changes, as there is the absence or presence of an aerenchymous center, and as the cross-sections look the least or the most like a cross-section through an internodal region.  Link here to be reminded.
 
THROUGH THE NODAL REGION
 
JUST BELOW THE PANICLE
 
THROUGH THE PANICLE