Question

Coralloid roots of _______ have symbiotic association with $N_2$ - fixing cyanobacteria.

• A. Pinus
• B. Cedrus
• C. Cycas
• D. Ginkgo

Answer 1

Answer: (C)

Cycas

The coralloid roots of Cycas are symbiotically associated with nitrogen fixing blue-green algae, Anabaena cycadae and Nostoc punctiforme. In the middle cortex of coralloid roots, there occurs a broad blue green zone, which is known as algal zone. Coralloid roots are irregular, negatively geotropic, dichotomously branched coral like roots which do not possess root hair and root caps.

So the correct option is C.