A medium-sized, intolerant pioneer similar to P. banksiana that is very common in the Rockies and western mountains (north to the Yukon). Bark is scaly. Needles are 2 per fascicle, about 2" long, and twisted. Cones are about 1 1/2" long, ovoid, and more or less serotinous with an umbo with a long, recurved, often deciduous spine.