Excerpts from Jim Conrad's
from the May 8, 2005 Newsletter issued from the Sierra Nevada foothills
somewhat east of Placerville, California, USA
PONDEROSA PINE JIGSAW-BARK
Pines dominate the slopes here and we have three pine species in the neighborhood. We're at the very uppermost elevation limit of Digger Pines and the very lowermost elevation limit of Sugar Pines. However we're in the center of the Ponderosa Pine zone, so those Ponderosas are the main tree around my trailer and the house. Below, you can see two Ponderosas outside my window as I type this:
Young Ponderosas are very similar to Loblollies back in Mississippi, but the above picture shows that adult Ponderosas are more slender and open than Loblollies and have thicker, straighter trunks.
On mature Ponderosa trees the bark forms flat, elongate plates maybe as wide as your hand and running up the tree, separated from one another by deep ridges. A remarkable thing is that the surfaces of those flat plates exfoliate in jigsaw-puzzle designs. You can see a close-up of such a plate below: