Scientific name: Pinus edulis Engelmann 1848
Synonyms: Caryopitys edulis (Engelm.) Small, Pinus cembroides subsp. edulis (Engelm.) A.E.Murray, Pinus cembroides var. edulis (Engelm.) Voss, Pinus monophylla var. edulis (Engelm.) M.E.Jones
Common names: Pinyon pine, Colorado pinyon, Two-needle pinyon pine, Two-leaf pinyon, Nut pine
Description
Tree to 10(-20) m tall, with trunk to 0.6(-1.7) m in diameter, but often dividing into several trunks at or near the base. Bark light brown, becoming shallowly furrowed between irregularly shaped and uneven small plates. Crown egg-shaped when young, progressively broadening with age, with numerous, upwardly angled branches from the base moderately clothed with foliage. Twigs hairless, light reddish brown at first, becoming light gray. Buds 5-10 mm long, resinous. Needles in bundles of (one or) two (or three), each needle 2-4.5(-6) cm long, gently curved, stiff, and sticking together, lasting 4-9 years, bright light green to bluish green. Individual needles with lines of stomates on both the inner and outer faces, an undivided midvein, and two resin canals touching the epidermis of the outer face about midway between the corners and the midline. Sheath 5-7 mm long, curling back and soon shed. Pollen cones 7-10 mm long, yellowish brown. Seed cones (3.5-)4-5 cm long, broadly egg-shaped to nearly spherical, with 15-40 seed scales, green before maturity, ripening yellowish brown, opening widely to release the seeds and then falling, unstalked or very short stalked. Seed scales oblong, with a deep recess for the seeds and a thickened, pyramid-shaped exposed portion angling outward and tipped by a stiff diamond-shaped umbo. Seed body 10-15 mm long, the shell 0.5-0.6 mm thick, unwinged or with a short, undeveloped wing remaining attached to the seed scale.
The edible pine nuts, or piñones (hence the scientific name), from this species have long been an important winter food for some peoples in the summer-rainfall deserts of the southwestern United States.
Southwestern United States, centered on the Four Corners area, from southwestern Wyoming, central Utah, and north-central Colorado to southeastern Arizona, southwestern New Mexico, and trans-Pecos Texas. Forming pure stands or mixed with junipers in pinyon-juniper woodland on dry slopes, hilltops, and tablelands; (900-)1,400-2,400(-3,200) m.
Conservation Status
Red List Category & Criteria: Least Concern
Despite evidence of some decline due to clearance of pinyon-juniper woodland in favour of pastureland, and extensive recent dieback associated with repeated droughts and pine bark beetle infestations, the extent of occurrence and area of occupancy of Pinus edulis are still well beyond any thresholds for a threatened category and it is therefore assessed as Least Concern.
The global population is very large, as its area of occupancy is in excess of 20,000 km² covering much of the so-called "Four Corner States" in the western USA.
Pinus edulis is widely distributed in the interior basins, plateaus, mesas and mountains of the 'Four Corner' States of the USA. It forms extensive, open stands commonly with one or more species of Juniperus known as Pinyon-Juniper woodland, which is one of the most widespread semi-arid vegetation types in North America. Summers are hot and winters cold, but climatic conditions are varying with altitude and latitude. Soils are commonly thin to sceletal or may be absent altogether, with the trees growing from fissures in the sandstone, limestone, or shale. Recent sedimentation accumulates in the basins and valley bottoms, where grasses and 'sagebrush' (Seriphidium tridentatum) dominate, while at higher elevations in the mountains the Pinyon-Juniper woodland gives way to open pine forest with Pinus ponderosa and Pseudotsuga menziesii. Juniperus monosperma and Juniperus osteosperma are the most commonly associated junipers with Pinus edulis. The appearance is of a stunted forest as the free-standing trees branch low and form wide spreading crowns while only attaining modest height. Depending on openness, there is an understorey dominated by shrubs of which Seriphidium (Artimisia) is most common and widespread, supplemented by scrubby oaks (Quercus spp.), Chrysothamus, Cercocarpus, Ephedra, Yucca, and several others depending on geographical area, as well as grasses and other herbs.
Although the species is too widespread and abundant to be threatened with extinction, the Pinyon-Juniper woodland as an ecosystem has been under threat in many places due to 'range improvement' for the grazing of cattle and sheep, causing the removal or degradation of the woodland over large areas. Over the last decade repeated droughts, combined with outbreaks of pine bark beetles have led to the death of many thousands of hectares of pinyon woodland.
Firewood from the Pinyon-Juniper woodland is the most common use both past and present. Pinyon pine wood has a higher than average heat value and burns with a distinctive aroma. Large quantities were logged and its rough timbers used as props in the mining boom of the late 19th century. Poor growth form from the forester's perspective renders the wood unsuitable for sawn timber, even though its quality matches that of Ponderosa pine. The edible seeds are easy to harvest and in great demand as a delicacy; they may constitute the economically most valuable product of the species. Crops can vary greatly from one year to the next and the slow growing pines do not perform well in plantations. Horticultural value is limited, although locally young trees are harvested as Christmas trees.
This species occurs in several protected areas, among which are famous national parks. Protection of Pinyon-Juniper woodland outside these areas is required to prevent eventual decline of this species.
Cultivars:
Pinus edulis ’Blue Jazz’
Pinus edulis ’Branson’
Pinus edulis ’Burr’
Pinus edulis ’Carbondale’
Pinus edulis ’Carmel’
Pinus edulis ’Chamisal’
Pinus edulis ’Cheese Box'
Pinus edulis ’Cliffside’
Pinus edulis ’Current Pass’
Pinus edulis ’Dominguez’
Pinus edulis ’Downhill’
Pinus edulis ’Fancy Nancy’
Pinus edulis ’Farmy’
Pinus edulis ’Gibbler’
Pinus edulis ’Juno’
Pinus edulis ’Lil Jake’
Pinus edulis ’Little Jare’
Pinus edulis ’Marshall’
Pinus edulis ’Montrose’
Pinus edulis ’My Nancy’
Pinus edulis ’Ojo’
Pinus edulis ’Old Yellow’
Pinus edulis ’Penasco’
Pinus edulis ’Poncha’
Pinus edulis ’Proctor Pinion’
Pinus edulis ’Pudgy’
Pinus edulis ’Raton’
Pinus edulis ’Salida’
Pinus edulis ’Sharps’
Pinus edulis ’Show Low’
Pinus edulis ’The Brad’
Pinus edulis ’Tiny Pout’
Pinus edulis ’Tiny Ration’
Pinus edulis ’Tiny Ripple’
Pinus edulis ’Trinidad’
Pinus edulis ’Uniweep’
Pinus edulis ’Unnamed Cultivar’
References
- Farjon, A. (2010). A Handbook of the World's Conifers. Koninklijke Brill, Leiden.
- Eckenwalder, J.E. (2009) Conifers of the World: The Complete Reference. Timber Press, Portland.
- IUCN Red List of Threatened Species, International Union for Conservation of Nature and Natural Resources. Cambridge, UK /Gland, Switzerland
Copyright © Aljos Farjon, James E. Eckenwalder, IUCN, Conifers Garden. All rights reserved.
