What is sapwood and does the floor have to have these lines?

Sapwood is an important structural component of wood and transports nutrients and water from the bark to the heartwood. It is natural and occurs in all tree species, usually visible as thin lines extending radially towards the center of the tree. These can vary in size but are more prominent in standing tree rings.

Sapwood is not considered a defect or quality issue as it is a natural part of the tree's anatomy and does not affect the strength or usefulness of the wood. Therefore, it is not considered a valid basis for a complaint. Sapwood also contributes to the aesthetic value of the wood, by providing unique patterns and variations that many appreciate in the final products. In Oak, it is a prominent part of the appearance.