Coralloid Root Structure

 

Coralloid roots:

Coralloid roots, also known as "coral-like roots," are specialized root structures found in some plants, particularly certain species of cycads and gymnosperms. These roots have unique features and functions that set them apart from typical plant roots. Here are some important notes on coralloid roots:

Structure:

The transverse section of the coralloid root is similar to that of normal root and it can be differentiated into epidermis, cortex and vascular tissue.

a. Epidermis:

In young root, it is similar to normal root. However, in old root the outermost tissue is periderm. It consists of 2 to 5 layers of dead cells.

b. Cortex:

The cortex is wider in comparison with the normal root. A greenish algal zone is present almost in the middle of the cortex and divides it into outer cortex and inner cortex. The algal zone consists of loosely co blue green algae (Anabaena cycadae, Nostoc punctiforme, Oscillatoria, Pseudomonas radicicola) and some fungi. The main function of these roots is nitrogen fixation due to the presence of cyanophycean members. Endodermis is similar to normal root.

c. Vascular tissue:

Endodermis is followed by multilayered parenchymatous pericycle. Vascular bundle Xylem is triarch and exarch. Secondary growth is very rare or absent. No secondary xylem or secondary phloem are developed although cork and cork cambium are present.