coralloid root

plant anatomy

Written by

The Information Architects of Encyclopaedia Britannica

Last updated

June 24, 2026

Quick Summary

The term "coralloid root" refers to a specific type of root found in cycadophytes, which are ancient seed plants. These roots are short and grow outward, giving them an irregular, beady appearance that resembles coral.1

The key feature of coralloid roots is their symbiotic relationship with cyanobacteria (blue-green algae). These cyanobacteria live within the root tissues and perform nitrogen fixation, converting atmospheric nitrogen into a usable form for the plant. In return, the plant provides the cyanobacteria with a protected environment and nutrients. This symbiotic relationship is crucial for the plant's survival, as it allows the plant to obtain essential nitrogen for growth, especially in nutrient-poor soils.12

Summary created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

3 Britannica Sources

Ask Britannica AI about this topic

Britannica doesn't have a full article on this topic, so we've curated a list of our relevant coverage.

cycadophyte
Roots
The coralloid roots contain symbiotic cyanobacteria (blue-green algae), which fix nitrogen and, in association with root tissues, produce such beneficial amino acids as asparagine and citrulline.
Read More
The coralloid roots contain symbiotic cyanobacteria (blue-green algae), which fix nitrogen and, in association with root tissues, produce such beneficial amino acids as asparagine and citrulline.
Read More