Pinus ponderosa, commonly known as the ponderosa pine,bull pine, blackjack pine, or western yellow-pine, is a very large pine tree species of variable habitat native to the western United States and Canada. It is the most widely distributed pine species in North America.:4
It grows in various erect forms from British Columbia southward and eastward through 16 western U.S. states and has been successfully introduced in temperate regions of Europe. It was first documented into modern science in 1826 in eastern Washington near present-day Spokane (of which it is the official city tree). On that occasion, David Douglas misidentified it as Pinus resinosa (red pine). In 1829, Douglas concluded that he had a new pine among his specimens and coined the name Pinus ponderosa for its heavy wood. In 1836, it was formally named and described by Charles Lawson, a Scottish nurseryman. It is the official state tree of Montana.
Pinus ponderosa is a large coniferouspine (evergreen) tree. The bark helps to distinguish it from other species. Mature to over-mature individuals have yellow to orange-red bark in broad to very broad plates with black crevices. Younger trees have blackish-brown bark, referred to as "blackjacks" by early loggers. Ponderosa pine's five subspecies, as classified by some botanists, can be identified by their characteristically bright, green needles (contrasting with blue-green needles that distinguish Jeffrey pine). The Pacific subspecies has the longest—19.8 cm or 7.8 in—and most flexible needles in plume-like fascicles of three. The Columbia ponderosa pine has long—12.0–20.5 cm or 4.7–8.1 in—and relatively flexible needles in fascicles of three. The Rocky Mountains subspecies has shorter—9.2–14.4 cm or 3.6–5.7 in—and stout needles growing in scopulate (bushy, tuft-like) fascicles of two or three. The southwestern subspecies has 11.2–19.8 cm or 4.4–7.8 in, stout needles in fascicles of three (averaging 69–89 mm (2.7–3.5 in)). The central High Plains subspecies is characterized by the fewest needles (1.4 per whorl, on average); stout, upright branches at narrow angles from the trunk; and long green needles—14.8–17.9 cm or 5.8–7.0 in—extending farthest along the branch, resembling a fox tail. Needles are widest, stoutest, and fewest (averaging 56–71 mm (2.2–2.8 in)) for the species.
Sources differ on the scent of P. ponderosa, but it is more or less of turpentine, reflecting the dominance of terpenes (alpha- and beta-pinenes, and delta-3-carene). Some state that it has no distinctive scent.
The National Register of Big Trees lists a ponderosa pine that is 235 ft (72 m) tall and 324 in (820 cm) in circumference. In January 2011, a Pacific ponderosa pine in the Rogue River–Siskiyou National Forest in Oregon was measured with a laser to be 268.35 ft (81.79 m) high. The measurement was performed by Michael Taylor and Mario Vaden, a professional arborist from Oregon. The tree was climbed on October 13, 2011, by Ascending The Giants (a tree-climbing company in Portland, Oregon) and directly measured with tape-line at 268.29 ft (81.77 m) high. This is the second tallest known pine after the sugar pine.
Modern forestry research has identified five different taxa of P. ponderosa, with differing botanical characters and adaptations to different climatic conditions. Four of these have been termed "geographic races" in forestry literature. Some botanists historically treated some races as distinct species. In modern botanical usage, they best match the rank of subspecies and have been formally published.
Range and climate: Four corners transition zone including southern Colorado, southern Utah, northern and central New Mexico and Arizona, westernmost Texas, and a single disjunct population in the far northwestern Oklahoma panhandle. The Gila Wilderness contains one of the world's largest and healthiest forests. Hot with bimodal monsoonal rainfall; wet winters and summers contrast with dry springs and falls; mild winters.
Pinus ponderosa subsp. critchfieldiana Robert Z. Callaham subsp. novo — Pacific ponderosa pine.
Range and climate: western coastal parts of Washington State; Oregon west of the Cascade Range except for the southward-extending Umpqua–Tahoe Transition Zone; California except for both that transition zone and the Transverse-Tehahchapi Mountains Transition zone in southern California and Critchfield's far Southern California Race. Mediterranean hot, dry summers in California; mild wet winters with heavy snow in mountains.
Range and climate: 100–2,700 metres (330–8,860 ft) on coastal-draining slopes of major mountain ranges in California, and in southwestern Oregon, Washington.
Pinus ponderosa subsp. ponderosaDouglas ex C. Lawson — Columbia ponderosa pine, North plateau ponderosa pine.
Range and climate: southeast British Columbia, eastern Washington State and Oregon east of the Cascade Range, 1,200–1,900 metres (3,900–6,200 ft) in northeastern California, Arizona, northwestern Nevada, Idaho and west of the Helena, Montana, transition zone. Cool, relatively moist summers; very cold, snowy winters (except in the very hot and very dry summers of central Oregon, most notably near Bend, which also has very cold and generally dry winters).
Pinus ponderosa subsp. readiana Robert Z. Callaham subsp. novo — central High Plains ponderosa pine.
Range and climate: southern South Dakota and adjacent northern Nebraska and far eastern Colorado, but neither the northern and southern High Plains nor the Black Hills, which are in P. p. scopulorun. Hot, dry, very windy summers; continental cold, wet winters.
Pinus ponderosa var. scopulorum (Engelm. in S.Watson) E. Murray, Kalmia 12:23, 1982 — Rocky Mountains ponderosa pine.
Range and climate: east of the Helena, Montana, transition zone, North & South Dakota, but not the central high plains, Wyoming, Nebraska, northern and central Colorado and Utah, and eastern Nevada. Warm, relatively dry summers; very cold, fairly dry winters.
Range and climate: predominantly in northeastern California, and into Nevada and Oregon, at 2,000–3,000 metres (6,600–9,800 ft), upper mixed-conifer to lower subalpine habitats.
Distributions of the subspecies in the United States are shown in shadow on the map. Distribution of ponderosa pine is from Critchfield and Little. The closely related five-needled Arizona pine (Pinus arizonica) extends southward into Mexico.
Before the distinctions between the North Plateau race and the Pacific race were fully documented, most botanists assumed that ponderosa pines in both areas were the same. When a botanist and a geneticist from California found in 1948 a distinct tree on Mt. Rose in western Nevada with some marked differences from the ponderosa pine they knew in California, they described it as a new species, Washoe pine Pinus washoensis. Subsequent research determined this to be one of the southern-most outliers of the typical North Plateau race of ponderosa pine.:30–31 Its current classification is Pinus ponderosa var. washoensis.
An additional variety, tentatively named P. p. var. willamettensis, found in the Willamette Valley in western Oregon, is rare. This is likely just one of the many islands of Pacific subspecies of ponderosa pine occurring in the Willamette Valley and extending north to the southeast end of Puget Sound in Washington.
Names of taxa and transition zones are on the map.
Numbers in columns were derived from multiple measurements of samples taken from 10 (infrequently fewer) trees on a varying number of geographically dispersed plots.
Numbers in each cell show calculated mean ± standard error and number of plots.
^Moore, Gerry; Kershner, Bruce; Craig Tufts; Daniel Mathews; Gil Nelson; Spellenberg, Richard; Thieret, John W.; Terry Purinton; Block, Andrew (2008). National Wildlife Federation Field Guide to Trees of North America. New York, New York: Sterling. p. 89. ISBN1-4027-3875-7.
^Safford, H.D. 2013. Natural Range of Variation (NRV) for yellow pine and mixed conifer forests in the bioregional assessment area, including the Sierra Nevada, southern Cascades, and Modoc and Inyo National Forests. Unpublished report. USDA Forest Service, Pacific Southwest Region, Vallejo, CA, 
^Lauria, F. (1996). The identity of Pinus ponderosa Douglas ex C. Lawson (Pinaceae). Linzer Biologische Beitraege.
^The agriculturist's manual: being a familiar description of agricultural plants cultivated in Europe. Edinburgh U.K.: William Blackwood and Sons. 1836.
^Dickson, Tom. "Ponderosa Pine". Montana Outdoors. Montana Fish, Wildlife & Parks. Retrieved February 18, 2015.
Conkle, MT; Critchfield, WB (1988). "Genetic variation and hybridization of ponderosa pine". In Baumgartner, DM; Lotan, JE. Ponderosa pine the species and its management. Cooperative Extension, Washington State University. pp. 27–44.
Critchfield, WB (1984). "Crossability and relationships of Washoe Pine". Madroño. 31: 144–170.
Critchfield, WB; Allenbaugh, GL (1965). "Washoe pine on the Bald Mountain Range, California". Madroño. 18: 63–64.