Colorado Pinyon

Colorado Pinyon
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The Colorado Pinyon or Two-needle Pinyon (Pinus edulis) is a pine in the pinyon pine group whose ancestor was a member of the Madro-Tertiary Flora (a group of drought resistant trees) and is native to the United States. The range is in Colorado, eastern and central Utah, northern Arizona, New Mexico and the Guadalupe Mountains in westernmost Texas. It occurs at moderate altitudes from 1600-2400 m, rarely as low as 1400 m and as high as 3000 m. It is widespread and often abundant in this region, forming extensive open woodlands, usually mixed with junipers. The Colorado pinyon (piñon) grows as the dominant species on 4.8 million acres (19,000 km²) in Colorado, making up 22% of the states 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 3170 m on Kendrick Peak in the Kaibab National Forest of northern Arizona.

It is a small to medium size tree, reaching 10-20 m tall and with a trunk diameter of up to 80 cm, rarely more. The bark is irregularly furrowed and scaly. The leaves (‘needles’) are in pairs, moderately stout, 3-5.5 cm 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, 3-5 cm 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 4-6 cm broad when mature, holding the seeds on the scales after opening. The seeds are 10-14 mm long, with a thin shell, a white endosperm, and a vestigial 1-2 mm wing; they are dispersed by the Pinyon Jay, which plucks the seeds out of the open cones. The jay, which uses the seeds as a food resource, stores many of the seeds for later use, and some of these stored seeds are not used and are able to grow into new trees.

Colorado Pinyon was described by George Engelmann in 1848 from collections made near Santa Fe, New Mexico on Alexander William Doniphan’s expedition to northern Mexico in 1846.

It is most closely related to the Single-leaf Pinyon, which hybridises with it occasionally where their ranges meet in western Arizona and Utah. It is also closely related to the Texas Pinyon, but is separated from it by a gap of about 100 km so does not hybridise with it.

An isolated population of trees in the New York Mountains of southeast California, previously thought to be Colorado Pinyons, have recently been shown to be a two-needled variant of Single-leaf Pinyon from chemical and genetic evidence. Occasional two-needled pinyons in northern Baja California, Mexico have sometimes been referred to Colorado Pinyon in the past, but are now known to be hybrids between Single-leaf Pinyon and Parry Pinyon.

The edible seeds, pine nuts, are extensively collected throughout its range; in many areas, the seed harvest rights are owned by Native American tribes, for whom the species is of immense cultural and economic importance. One early legend asserts that the “tree of life” is a pinyon pine, rooted in ancient cultural sites found within areas of Pinyon (Piñon) Canyon, Colorado.

The destruction of large areas of pinyon forests in the interests of cattle ranching is seen by many as an act of major ecological and cultural vandalism. Colorado Pinyon is also occasionally planted as an ornamental tree and sometimes used as a Christmas tree. One historical use relates that the burning wood of the pinyon pine is the ancient fuel source of the eternal flame.