Krummholz is a German word meaning “crooked wood.” It is used to designate the dwarfed and deformed coniferous vegetation of the transition zone between subalpine forest and the treeless alpine tundra. Because of a mixing of species from each region, the krummholz, an ecotone, has a richer flora than either alone. Wind speeds may exceed one hundred miles per hour in krummholz, snow can accumulate to depths of twelve feet, and the growing season is often less than two months. The crowns of trees here often become one-sided as their windward branches fail to develop. The result is a low deformed wood of asymmetrical “flag trees” and low-branching, interwoven mats of foliage. Krummholz systems in the southern Rocky Mountains run in a band between 11,000 and 12,000 feet of elevation. These trees are surviving at their environmental limit, so growth is slow and irregular. Trees several hundred years old may have a trunk diameter of four inches, and may be only a few feet tall.

William Kittredge