Identifying Fungal Growth on a Tree Trunk

What You’re Seeing

The photo shows a shelf‑like structure with visible gills on the bark—a classic sign of a basidiomycete fungus (a wood‑decay mushroom). The gills produce microscopic spores that spread the fungus.

What It Means for the Tree

• Some wood‑decay fungi attack living tissue, while others only colonize dead wood.
• Seeing a fruiting body (the visible “mushroom”) often indicates internal decay has been progressing for some time.

Next Steps

Because the extent of internal rot can’t be judged from the outside, consult a certified arborist. They can assess structural stability and recommend whether the tree needs treatment, monitoring, or removal for safety.