Q.What is Coralloid root? Give an example.

Coralloid roots are specialised, coral-shaped roots of Cycas that grow upward (above the soil) and house nitrogen-fixing cyanobacteria in a mutualistic relationship.

A coralloid root is a specialised, dichotomously and repeatedly branched root that resembles a piece of coral in appearance — hence the name. It is a distinctive feature of gymnosperms of the genus Cycas.

Key features of coralloid roots:

1. Position and growth: Unlike normal roots, coralloid roots grow upward, partly or wholly above the soil surface (they are negatively geotropic).

2. Symbiotic association: The cortex of a coralloid root harbours symbiotic nitrogen-fixing cyanobacteria, most commonly Anabaena (and sometimes Nostoc), living in a special zone of the cortical tissue.

   …