If a dog ingests hydrangea material, which part of the plant is confirmed to pose a poisoning risk?

Answer

Any part (leaves, buds, or flowers)

Ingestion of any component of the plant, including foliage, flower heads, or buds, carries a recognized risk of poisoning.

If a dog ingests hydrangea material, which part of the plant is confirmed to pose a poisoning risk?
plantPoisonSafetyDoghydrangea