A few varieties of trees have spiral twisting fibrous trunks. These adaptations are thought to strengthen trunks against the forces of wind, and in our northern climate, also windy winter conditions with a snow load. When we hike the montane forests of our area, we can spot pine tree stumps with the twist patterns. At higher altitudes some of the stunted spruce trees also show the twisted trunks, with the spiral developing in a clockwise pattern.

On the rocky hillsides of our area, juniper trunks twist as they grow.

Some species are more pronounced. Junipers in dry areas in the southwest can be very twisted, but extreme conditions contorts the spiral pattern.

The tendency for the bark to grow in spiral pattern reduces wind stresses on the tree. We can see this mostly easily with pines, oaks, and junipers, but many trees exhibit this growth pattern. Watch for it while you hike in the hills. Do the spiral twisted trunks groan in the wind like the straighter trunks?