Which of the following is NOT a type of response growth wood?

Response growth wood refers to specialized wood that trees produce in response to various stresses or injuries. This type of wood adapts the tree to better withstand environmental challenges.

Compression wood is indeed a type of response growth wood, particularly found on the lower side of leaning conifers. It is produced to provide support and stability for the tree as it adjusts to its position.

The other types of response growth wood—flexure wood, reaction wood, and woundwood—are also adaptations to stress and injury. Flexure wood helps trees resist bending forces, reaction wood helps stabilize a tree when it’s leaning, and woundwood is generated in response to injuries, forming around wounds to protect the tree.

Understanding these distinctions is crucial for tree risk assessment, as identifying the types of response growth wood can provide insight into the tree's health and structural integrity. Therefore, the option that does not belong to this category of response growth wood is indeed compression wood.