What is the common technique used for woody stem plants that involves making a shield-shaped cut?

The technique that involves making a shield-shaped cut is known as a heal cutting. This form of propagation is particularly effective for woody stem plants because it allows the cutting to maintain some of the stem's vascular tissue, promoting better healing and growth once planted. The specific shape of the cut helps in the formation of the callus and subsequent root development, maximizing the chances of successful propagation.

This method is distinct from others listed. Leaf section cuttings and leaf petiole cuttings are techniques used primarily for herbaceous plants and do not involve the stem in the same way, focusing instead on leaf sections. Cane cuttings refer to a method of propagating certain types of plants (like certain types of vines) by cutting the stems into sections, but they do not involve the shield shape. Thus, the heal cutting technique is specifically tailored for woody plants, making it the correct choice in this context.