Plate XXIII. Pinus Apacheca showing crown form in open stand, 40 feet high
and 20 inches in diameter.
Illustration by A.E. Hoyle (signed lwer left), in:
Sudworth, George B. The Pine Trees of the Rocky Mountain Region (Washington,
D.C.: Government Printing Office, 1917) USDA Bulletin No. 460.
U.S. Forest Service Headquarters History Collection.