The wood of each tree species varies with the environmental conditions under which the trees grow. Under certain conditions wood is formed that is distinctly abnormal in its structure and properties. One such type of abnormal wood is the so-called compression wood formed on the lower, or compression, side of branches and of leaning tree trunks of all coniferous species. Other names applied to compression wood are hard grain, timber bind, pressure wood, Rotholz (German), Druckholz (German), bois rogue (French), and tenar (Swedish).