Mitre joint in pine
A mitre joint in pine joins pieces whose ends are cut at matching angles. White pine is one of the woods recommended for this mitre work.
Choice of wood
Audels (1923) names white pine and oak as preferable woods for mitre work. The account warns that many other woods are more liable to warp and split when affected by climatic changes or steam heat.
Keeping the cut true
When a piece warps or splits, the cut can vary and go out of true, according to Audels (1923). The guidance links the choice of pine to keeping mitre cuts accurate under the conditions described.