Pinus ponderosa, commonly known as the ponderosa pine or western yellow pine, is a very large pine tree species of variable habitat native to mountainous regions of western North America. It is the most widely distributed pine species in North America.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 Unpublished report.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,
Pinus ponderosa grows in various erect forms in 16 western U.S. states as well as British Columbia in Canada and has been introduced in temperate regions of Europe and in New Zealand. It was first documented in 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 was adopted as the official state tree of Montana in 1949.
Other vernacular names that have been used for the species are "bull pine" and "blackjack pine", but these are general woodsmans terms applied to growth stages of several different pines, rather than specific to Pinus ponderosa.
Description
Pinus ponderosa is a large coniferous tree. The bark helps distinguish it from other species. Mature to overmature 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. The five varieties or 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 at and most flexible needles in plume-like fascicles of three, and green immature cones. The North Plateau or Columbia ponderosa pine has long and relatively flexible needles in fascicles of three, and purple immature cones. The Rocky Mountains subspecies has shorter and stouter needles growing in bushy, tuft-like fascicles of two or three, and usually green immature cones (but purple at high altitudes). The southwestern subspecies has stout needles long, in fascicles of three (averaging ). The central High Plains subspecies is characterized by the fewest branches (1.4 per whorl, on average; stout, upright branches at narrow angles from the trunk; and long green needles extending farthest along the branch, resembling a fox tail. Needles are widest, stoutest, and fewest (averaging ) for the species.
The egg-shaped cones, which are often found in great number under trees, are long. Each scale has a sharp point.
Sources differ on the scent of P. ponderosa. Some state that the bark smells of turpentine, which could reflect the dominance of terpenes (alpha- and beta-pinenes, as well as delta-3-carene). Others state that it has no distinctive scent, while still others state that the bark smells like vanilla if sampled from a furrow. Sources agree that the Jeffrey pine is more strongly scented than the ponderosa pine. When carved into, pitch-filled stumps emit a scent of fresh pitch.
Size
The National Register of Big Trees lists a ponderosa pine that is tall and 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 high. The measurement was performed by Michael Taylor and Mario Vaden, a professional arborist from Oregon. The tree was climbed on 13 October 2011, by Ascending The Giants (a tree-climbing company in Portland, Oregon) and directly measured with tape-line at high. As of 2015, a Pinus lambertiana specimen was measured at , which surpassed the ponderosa pine previously considered the world's tallest pine tree.
Taxonomy Pinus ponderosa was scientifically described and named by Charles Lawson working from information provided by David Douglas in 1836.
The taxonomy of the ponderosa pine is heavily disputed by botanists and foresters. In a pair of research papers in 2013 for the US Forest Service, Robert Z. Callaham concluded that it is a single species from the Rocky Mountains to the Pacific coast divided into five subspecies. However, the USDA Natural Resources Conservation Service PLANTS database (PLANTS) lists these as varieties . In the World Plants database maintained by Michael Hassler only three varieties are recognized, one described in 2024. On the other hand the World Flora Online (WFO) lists just two varieties. The Plants of the World Online (POWO) lists four varieties, but separates out two other taxa recognized as varieties as species. Similarly to POWO Christopher J. Earle writes in the Gymnosperm Database that the ponderosa pine has three subspecies and recognizes two taxa as species. In the Flora of North America (FNA) three varieties are recognized.
Subspecies and varieties
Pinus ponderosa subsp. benthamiana (Hartw.) Silba, syn. Pinus benthamiana Hartw., Pinus ponderosa var. benthamiana (Hartw.) Vasey, Pinus ponderosa subsp. critchfieldiana Callaham (nom. superfl.), Pinus ponderosa var. pacifica J.R.Haller & Vivrette (nom. superfl.) – Pacific ponderosa pine The Olympic Peninsula in Washington State, Oregon west of the Cascade Range, the whole of California, and far western Nevada, at on coastal-draining slopes of major mountain ranges. This is recognized by GRIN and PLANTS as the correct name for Callaham's subspecies critchfieldiana. It is also accepted by POWO but at varietal rank, but is currently considered a synonym of var. ponderosa by both World Plants and WFO. Both Callaham, and Haller & Vivrette, cited Hartweg's older name benthamiana in the synonymies of their new names, thus making them both invalid nomina superflua under Article 52 of the ICN. Despite this, POWO currently accepts var. pacifica. Pinus ponderosa subsp. brachyptera (Engelm.) Silba, syn. Pinus brachyptera Engelm., Pinus ponderosa var. brachyptera (Engelm.) Lemmon – southwestern ponderosa pine Four corners transition zone, including southern Colorado, southern Utah, northern and central New Mexico and Arizona, westernmost Texas, and a single small population in the far northwestern Oklahoma panhandle. The Gila Wilderness contains one of the largest and healthiest forests. Hot with bimodal monsoonal rainfall; wet winters and summers contrast with dry springs and falls; mild to cold winters. This taxon is recognized by Callaham and GRIN as a subspecies, and in PLANTS at varietal rank, but is considered a synonym of var. scopulorum by WFO and FNA, of var. ponderosa by World Plants, and as the species Pinus brachyptera by POWO. Pinus ponderosa subsp. ponderosa Douglas ex C. Lawson – North plateau ponderosa pine, Columbia ponderosa pine This is the autonymic subspecies of the species. Its range depends upon how many other taxa are combined with it. When treated as distinct as in Callaham, GRIN and the Jepson Herbarium, its range is from southeast British Columbia south through Washington and Oregon east of the Cascade Range to northeast California and western Nevada east of the Sierra Nevada, and in Idaho and western Montana. This area has 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). As combined with subsp. benthamiana as in FNA it extends further south into California, but their treatment excludes western Montana. Pinus ponderosa subsp. scopulorum (Engelm.) A.E.Murray, syn. Pinus ponderosa var. scopulorum Engelm., Pinus scopulorum (Engelm.) Lemmon – Rocky Mountains ponderosa pine This is recognized by Callaham and GRIN as a subspecies, and by WFO as a variety, PLANTS, World Plants, and the FNA. It is considered a separate species by POWO. The distribution of this taxa differs depending on its definition, being very widespread in the FNA's old, broad circumscription, and much more restricted by Callaham and in GRIN and POWO. Pinus ponderosa subsp. readiana Callaham – Central High Plains ponderosa pine This is recognized by Callaham and GRIN as a subspecies, but not accepted by any of the other authorities, who all include its distribution mapped by Callaham within subsp./var. scopulorum. It includes the populations in southern South Dakota, Nebraska, and southeast Wyoming at lower altitudes on drier sites than typical of scopulorum.
Distributions of the subspecies in Canada and the United States are shown on the map. Distribution of ponderosa pine is from Critchfield and Little.
Before the distinctions between the North Plateau and Pacific taxa were fully documented, most botanists assumed that ponderosa pines in both areas were the same. In 1948, when a botanist and a geneticist from California found a distinct tree on Mount 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 H.Mason & Stockw. Subsequent research determined this to be one of the southernmost outliers of the typical North Plateau race of ponderosa pine. Trees of the North Plateau ponderosa indistinguishable from washoensis can be found as far north as Promontory Hill near Merritt in British Columbia in Canada. Some authors accept it as a valid variety Pinus ponderosa var. washoensis (H.Mason & Stockw.) J.R. Haller & Vivrette, while others treat it without distinction as a synonym of subsp./var. ponderosa. It has been reported from , in upper mixed-conifer to lower subalpine habitats.
An additional possible variety, not formally described but colloquially named Willamette Valley ponderosa pine, is found in the Willamette Valley in western Oregon, where it 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.
The closely related five-needled Arizona pine (Pinus arizonica) extends southward into Mexico. It was formerly often treated as another variety, as Pinus ponderosa var. arizonica (Engelm.) Shaw, but is now generally recognized as a separate species.
Distinguishing subspecies The subspecies of P. ponderosa can be distinguished by measurements along several dimensions: