There is a Subterranean Rhizome.

The Rhizome Apices can become Aerial Shoots which then produce Leaves.

Roots are not present at any stage of the life cycle.

The Apical Meristem is an
Apical Cell.

Irregular Dichotomous Branching occurs with the Rhizome.

The Epidermis produces Hairs called Rhizoids. These have have a uniform distribution.

Rhizoids may form Unicellular Filaments which act as Gemmae.

Mycorrhizal Fungi are present in the Cortex of the Rhizome.

They pervade the Cortical Parenchyma cells & Increase the Absorptive System for the Rhizome by connecting it with external fungal hyphae.

The Cortex also has cells which Store Starch & contain Tannins.

Sclerenchyma is well developed in the inner Cortex.

  
Unstained Sclerenchyma Cells from the inner Cortex of the Rhizome seen with Bright Field (left) and crossed polarizers (right).

An Endodermis with a Casparian Strip is present. This is Very Important to remember!!!!!!

The Stele
is everything inside the Endodermis.

It always contains the Vascular Tissues, Xylem & Phloem.

A Parenchyma layer may be present as a buffer layer between the Endodermis and the Vascular Tissues. This is called the Pericycle. Pericycle means around the wheel. The Wheel is the Vascular Cylinder.

 
Psilotum Rhizome System

Psilotum Rhizome Tip
Note the many Brown Hairs which are called Rhizoids.



Commercial Slides of Rhizome Cross Sections


Cross Section of Psilotum Rhizome with a Mycorrhizal Fungus. The Brown areas contain Fungal Hyphae.

Unstained Cross Section from Psilotum Rhizome: Note the ring of thick-walled Sclerenchyma in the inner Cortex (Ground Tissue).

Unstained Cross Section from Psilotum Rhizome with crossed Polarizers

Inner Cortex and Stele (Xylem & Phloem) from Unstained Psilotum Rhizome Stained with Sudan Red. The Rhizome has the simplest Stele (Haplostele; Haplo = Simple)

 

Endodermal Cells from Rhizome Stained with Sudan Red & viewed with Crossed Polarizers: Note the Casparian Strip