Which of the following are the specialised roots of Cycas that are associated with nitrogen-fixing cyanobacteria? 

Coralloid roots are specialised roots found in Cycas sp. that are associated with nitrogen-fixing cyanobacteria. The coralloid root contains the cyanobacterial zone, which is inhabited by cyanobacteria. This has unique properties that contribute to the close relationship between Cycas sp. and cyanobacteria.