Cycas- Normal vs Coralloid Root
Cycas is a Gymnosperm coming under the Class Cycadopsida and Order Cycadales. Cycas plants have TWO types of Roots – (1) Normal Roots and (2) Coralloid Roots. In this post, we discuss the Similarities and Differences between Normal Root and Coralloid Roots in Cycas with a Comparison Table.
Similarities between Normal Root and Coralloid Root
Ø Anatomically both the roots are differentiated into epidermis, cortex, endodermis, pericycle and stele.
Ø The stele in both the groups composed of radially arranged xylem and phloem.
Ø Pith is absent or small in both the groups
Difference between Normal Root and Coralloid Root
Normal Root Coralloid Root
Morphology 
Development Develop from the radicle of embryo. Develop from the normal roots
Tap-root From the tap-root system. Do not form the tap-root.
Geotropism Positively geotropic and grow downward. Negatively geotropic and grow upward.
Branching Comparatively less branched. Coralloid roots are highly dichotomously branched.
Appearance Appear as normal roots of plants. Appear as corals (due to severe branching).
Root Hairs Root hairs are present. Root hairs are absent.
Cortex Cortex is small and uniform Cortex is very large and differentiated into THREE zones – outer, middle and inner zones.
Algal Zone Algal zone is absent in the cortex. A broad algal zone is present in the middle cortex.
Symbiosis NO symbiotic association with blue-green algae. Blue-green algae present in the algal zone of cortex shows symbiotic association with the root.
Vascular Tissue Vascular tissue is diarch (two strands of xylem and phloem). Vascular tissue is triarch (three strands of xylem and phloem).
Secondary Thickening Secondary thickening occurs. Secondary thickening is usually absent.
Function The main function of the normal root is absorption and anchorage. Function coralloid root is nitrogen fixation.
Anatomy 
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@. Gymnosperms: General Characters
@. Gymnosperms: Classification
@. Cycas – Morphology, Anatomy, Reproduction & Life Cycle
@. Economic Importance of Gymnosperms