Pinus edulis, the Colorado pinyon, two-needle piñon, pinyon pine, or simply piñon, is a pine in the pinyon pine group whose ancestor was a member of the Madro-Tertiary Geoflora (a group of drought resistant trees) and is native to the United States. Distribution and habitat The range in the U.S. is in Colorado, southern Wyoming, eastern and central Utah, northern Arizona, New Mexico, western Oklahoma, southeastern California, and the Guadalupe Mountains in far western Texas, as well as northern Mexico. It occurs at moderate elevations of , rarely as low as and as high as . It is widespread and often abundant in this region, forming extensive open woodlands, usually mixed with junipers in the pinyon-juniper woodland plant community. The Colorado pinyon (piñon) grows as the dominant species on 4.8 million acres () in Colorado, making up 22% of the state's forests. The Colorado pinyon has cultural meaning to agriculture, as strong piñon wood "plow heads" were used to break soil for crop planting at the state's earliest known agricultural settlements. There is one known example of a Colorado pinyon growing amongst Engelmann spruce (Picea engelmannii) and limber pine (Pinus flexilis) at nearly on Kendrick Peak in the Kaibab National Forest of northern Arizona. Description The piñon pine (Pinus edulis) is a small to medium size tree, reaching tall and with a trunk diameter of up to , rarely more. Its growth is "at an almost inconceivably slow rate" growing only six feet (1.8 meters) in one hundred years under good conditions. for an average growth of 0.72 inch (18 millimeters)per year. The bark is irregularly furrowed and scaly. The leaves ('needles') are in pairs, moderately stout, long, and green, with stomata on both inner and outer surfaces but distinctly more on the inner surface forming a whitish band. The cones are globose, long and broad when closed, green at first, ripening yellow-buff when 18–20 months old, with only a small number of thick scales, with typically 5–10 fertile scales. The cones open to broad when mature, holding the seeds on the scales after opening. The seeds are long, with a thin shell, a white endosperm, and a vestigial wing. The species intermixes with Pinus monophylla sbsp. fallax (see description under Pinus monophylla) for several hundred kilometers along the Mogollon Rim of central Arizona and the Grand Canyon resulting in trees with both single- and two-needled fascicles on each branch.