A Jain may avoid mushrooms even if they grow on tree bark because the rule is about the living being itself, not the surface it grows on.

Why mushrooms are avoided

In Jain view, mushrooms are generally treated as undesirable food because they are:

• a separate life-form from the tree bark,
• often grown in damp, decaying, dark places,
• associated with many subtle living beings and heavy harm in harvesting,
• and not considered a simple, pure plant part like bark, leaf, fruit, or seed.

Why cinnamon bark can be eaten

Cinnamon bark is different. It is:

• a plant part,
• usually dried bark taken from the plant,
• and not treated as a separate organism like a mushroom.

So even though both may come from a tree, cinnamon is plant bark, while mushrooms are fungi, and Jain dietary discipline treats them differently.

In simple words

• Tree bark = part of the plant
• Mushroom = a different living being

So a Jain may eat cinnamon bark but avoid mushrooms, even if mushrooms are growing on tree bark.