Pinus ponderosa

Last updated

Pinus ponderosa
Pinus ponderosa 15932.JPG
Pinus ponderosa subsp. ponderosa
Scientific classification Red Pencil Icon.png
Kingdom: Plantae
Clade: Tracheophytes
Division: Pinophyta
Class: Pinopsida
Order: Pinales
Family: Pinaceae
Genus: Pinus
Subgenus: P. subg. Pinus
Section: P. sect. Trifoliae
Subsection: P. subsect. Ponderosae
P. ponderosa
Binomial name
Pinus ponderosa
Pinus ponderosa subspecies range map 1.png
Natural range of Pinus ponderosa
green - P. ponderosa ssp. ponderosa
red - P. ponderosa ssp. benthamiana
blue - P. ponderosa ssp. scopulorum
yellow - P. ponderosa ssp. brachyptera

Pinus ponderosa, commonly known as the ponderosa pine, [2] bull pine, blackjack pine, [3] western yellow-pine, [4] or filipinus 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. [5] :4


Pinus ponderosa 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 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 [6] for its heavy wood. In 1836, it was formally named and described by Charles Lawson, a Scottish nurseryman. [7] It is the official state tree of Montana. [8]


Pinus ponderosa in Idaho PonderosaPinebarkidaho.JPG
Pinus ponderosa in Idaho

Pinus ponderosa is a large coniferous pine (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—7.8 in (19.8 cm)—and most flexible needles in plume-like fascicles of three. The Columbia ponderosa pine has long—4.7–8.1 in (12.0–20.5 cm)—and relatively flexible needles in fascicles of three. The Rocky Mountains subspecies has shorter—3.6–5.7 in (9.2–14.4 cm)—and stout needles growing in scopulate (bushy, tuft-like) fascicles of two or three. The southwestern subspecies has 4.4–7.8 in (11.2–19.8 cm), stout needles in fascicles of three (averaging 2.7–3.5 in (69–89 mm)). 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—5.8–7.0 in (14.8–17.9 cm)—extending farthest along the branch, resembling a fox tail. Needles are widest, stoutest, and fewest (averaging 2.2–2.8 in (56–71 mm)) for the species. [9] [10] [11]

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, and delta-3-carene). [12] Others state that it has no distinctive scent, [13] while still others state that the bark smells like vanilla if sampled from a furrow of the bark. [14] Sources agree that the Jeffrey pine is more strongly scented than the ponderosa pine. [13] [15]


The National Register of Big Trees lists a ponderosa pine that is 235 ft (72 m) tall and 324 in (820 cm) in circumference. [16] 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. [17] [18] This is the second tallest known pine after the sugar pine.


This species is grown as an ornamental plant in parks and large gardens.[ citation needed ]

Use in nuclear testing

During Operation Upshot–Knothole in 1953, a nuclear test was performed in which 145 ponderosa pines were cut down by the United States Forest Service and transported to Area 5 of the Nevada Test Site, where they were planted into the ground and exposed to a nuclear blast to see what the blast wave would do to a forest. The trees were partially burned and blown over. [19]

Ecology and distribution

Subspecies P. p, scopulorum, Custer State Park, South Dakota Pinus ponderosa scopulorum Custer State Park SD.jpg
Subspecies P. p, scopulorum, Custer State Park, South Dakota

Pinus ponderosa is a dominant tree in the Kuchler plant association, the ponderosa shrub forest. Like most western pines, the ponderosa generally is associated with mountainous topography. However, it is found on banks of the Niobrara River in Nebraska. Scattered stands occur in the Willamette Valley of Oregon and in the Okanagan Valley and Puget Sound areas of Washington. Stands occur throughout low level valleys in British Columbia reaching as far north as the Thompson, Fraser and Columbia watersheds. In its Northern limits, it only grows below 1,300m (4,200ft) elevation, but is most common below 800m (2,600ft). Ponderosa covers 1 million acres (4,000 km2), or 80%, [20] of the Black Hills of South Dakota. It is found on foothills and mid-height peaks of the northern, central, and southern Rocky Mountains, in the Cascade Range, in the Sierra Nevada, and in the maritime-influenced Coast Range. In Arizona, it predominates on the Mogollon Rim and is scattered on the Mogollon Plateau and on mid-height peaks in Arizona and New Mexico. [21] It extends into Mexico, as well. [22]

The fire cycle for ponderosa pine is 5 to 10 years, in which a natural ignition sparks a low-intensity fire. [23]

Pinus ponderosa needles are the only known food of the caterpillars of the gelechiid moth Chionodes retiniella. [24] Blue stain fungus, Grosmannia clavigera, is introduced in sapwood of P. ponderosa from the galleries of all species in the genus Dendroctonus (mountain pine beetle), which has caused much damage. Western pine and other beetles can be found consuming the bark. The seeds are eaten by squirrels, chipmunks, quail, grouse, and Clark's nutcracker, while mule deer browse the seedlings. [25]


Pinus ponderosa is affected by Armillaria , Phaeolus schweinitzii , Fomes pini , Atropellis canker , dwarf mistletoe, Polyporus anceps, Verticicladiella , Elytroderma needlecast and western gall rust. [26]


It attracts the western pine beetle and mountain pine beetle. [26]


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. [9] [10]

Subspecies and varieties

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. [28] The Gila Wilderness contains one of the world's largest and healthiest forests. [29] Hot with bimodal monsoonal rainfall; wet winters and summers contrast with dry springs and falls; mild winters.
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.
100–2,700 m (330–8,860 ft) on coastal-draining slopes of major mountain ranges in California, and in southwestern Oregon, Washington. [30]
Southeast British Columbia, eastern Washington State and Oregon east of the Cascade Range, 1,200–1,900 m (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). [33] [34]
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.
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.
Predominantly in northeastern California, and into Nevada and Oregon, at 2,000–3,000 m (6,600–9,800 ft), upper mixed-conifer to lower subalpine habitats. [37] [38]

Distributions of the subspecies in the United States are shown in shadow on the map. Distribution of ponderosa pine is from Critchfield and Little. [39] 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. [9] :30–31 [40] [41] [42] Its current classification is Pinus ponderosa var. washoensis. [36] [37] [38]

An additional variety, tentatively named P. p. var. willamettensis, found in the Willamette Valley in western Oregon, is rare. [43] 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.

Distinguishing subspecies

The subspecies of P. ponderosa can be distinguished by measurements along several dimensions: [9] :23–24 [10] :17

 Common name Pacific  Columbia  Rocky Mountains  Southwestern  Central High Plains 
 Scientific name P. p. critchfieldiana  P. p. ponderosa  P. p. scopulorum  P. p. brachyptera  P. p. readiana 
 Years needles remain green 3.9±0.25, N=30  4.7±0.14, N=50  5.7±0.28, N=23  4.3±0.18, N=24  4.7±0.18, N=5 
 Foliage length on branch (cm) 25.1±2.4, N=30  26.2±2.2, N=50  21.1±1.7, N=23  21.8±2.7, N=24  42.2±6.7, N=5 
 Needle length (cm) 19.8±0.44, N=30  16.8±0.29, N=48  11.2±0.27, N=23  14.7±0.45, N=24  15.6±0.57, N=5 
 Needles per fascicle 3.0±0.00, N=30  3.0±0.00, N=48  2.6±0.06, N=23  3.0±0.03, N=24  2.4±0.11, N=5 
 Needle thickness 45.9±0.49, N=30  47.8±0.51, N=48  46.4±0.68, N=23  44.8±0.87, N=24  49.7±0.61, N=5 
 Branches per whorl 4.4±0.13, N=30  3.7±0.11, N=50  3.0±0.17, N=23  3.4±0.25, N=23  2.3±0.11, N=5 
 Branch angle (° from vertical) 56±1.8, N=30  51±1.7, N=50  50±2.3, N=23  48±3.1, N=24  36±1.9, N=5 
 Seed cones length (mm) 101.4±2.48, N=25  88.7±1.24, N=36  70.7±2.20, N=22  74.9±2.51, N=20  71.1±2.46, N=5 
 Seed cones width (mm) 77.1±1.35, N=25  71.6±0.73, N=36  61.5±1.08, N=22  62.6±1.77, N=20  63.3±2.18, N=5 
 Seed cone form W/L 0.80±0.03, N=25  0.84±0.03, N=36  0.90±0.02, N=22  0.86±0.02, N=20  0.90±0.03, N=5 
 Seed length (mm) 7.5±0.08, N=23  7.6±0.16, N=14  6.3±0.09, N=17  6.4±0.18, N=16  7.0±0.12, N=5 
 Seed width (mm) 4.9±0.05, N=23  4.9±0.08, N=14  4.1±0.05, N=17  4.3±0.09, N=16  4.5±0.10, N=5 
 Seed + wing length (mm) 32.3±0.58, N=23  24.8±0.62, N=14  22.9±0.63, N=17  23.3±0.68, N=15  23.1±0.78, N=5 
 Mature cone color [44]  apple green to yellow green green & red-brown to dark purple green & red-brown to dark purple  green & red-brown to dark purple


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.


Pinus ponderosa is the official state tree of Montana. In a 1908 poll to determine the state tree, Montana schoolchidren chose the tree over the Douglas fir, American larch, and cottonwood. However, the tree was not officially named the state tree until 1949. [45]

See also

Related Research Articles

Pine Genus of plants in the conifer family Pinaceae

A pine is any conifer in the genus Pinus of the family Pinaceae. Pinus is the sole genus in the subfamily Pinoideae. The Plant List compiled by the Royal Botanic Gardens, Kew and Missouri Botanical Garden accepts 126 species names of pines as current, together with 35 unresolved species and many more synonyms. Pine may also refer to the lumber derived from pine trees; pine is one of the more extensively used types of wood used as lumber.

Douglas fir species of tree

Pseudotsuga menziesii is an evergreen conifer species in the pine family, Pinaceae. It is native to western North America and is known as Douglas fir, Douglas-fir, Oregon pine, and Columbian pine. There are three varieties: coast Douglas-fir, Rocky Mountain Douglas-fir and Mexican Douglas fir.

<i>Pinus balfouriana</i> species of plant

Pinus balfouriana, the foxtail pine, is a rare high-elevation pine that is endemic to California, United States. It is closely related to the Great Basin and Rocky Mountain bristlecone pines, in the subsection Balfourianae. The two disjunct populations are found in the southern Klamath Mountains and the southern Sierra Nevada. A small outlying population was reported in southern Oregon, but was proven to have been misidentified.

<i>Pinus sabiniana</i> species of plant

Pinus sabiniana, with the common names gray pine, foothill pine, and the more historically and internationally used digger pine, is a pine endemic to California in the United States. According to, "The terms 'foothills pine' or 'gray pine' are now officially preferred", however, other names also exist.

Western white pine species of plant, Western White Pine

Western white pine also called silver pine, and California mountain pine, in the family Pinaceae, is a species of pine that occurs in the mountains of the western United States and Canada, specifically the Sierra Nevada, the Cascade Range, the Coast Range, and the northern Rocky Mountains. The tree extends down to sea level in many areas, particularly in Oregon and Washington. It is the state tree of Idaho, and is sometimes known as the Idaho pine.

<i>Pinus mugo</i> Species of plant

Pinus mugo, known as bog pine, creeping pine, dwarf mountain pine, mugo pine, mountain pine, scrub mountain pine or Swiss mountain pine, is a species of conifer, native to high elevation habitats from southwestern to Central Europe and Southeast Europe.

<i>Pinus nigra</i> species of plant

Pinus nigra, the Austrian pine or black pine, is a moderately variable species of pine, occurring across southern Mediterranean Europe from Spain to the eastern Mediterranean, on the Anatolian peninsula of Turkey on Corsica and Cyprus as well as Crimea and in the high mountains of the Maghreb in North Africa.

<i>Pinus jeffreyi</i> species of plant, Jeffrey Pine

Pinus jeffreyi, also known as Jeffrey pine, Jeffrey's pine, yellow pine and black pine, is a North American pine tree. It is mainly found in California, but also in the westernmost part of Nevada, southwestern Oregon, and northern Baja California. It is named in honor of its botanist documenter John Jeffrey.

<i>Pinus flexilis</i> species of plant

Pinus flexilis, the limber pine, is a species of pine tree-the family Pinaceae that occurs in the mountains of the Western United States, Mexico, and Canada. It is also called Rocky Mountain white pine.

<i>Pinus contorta</i> species of plant

Pinus contorta, with the common names lodgepole pine and shore pine, and also known as twisted pine, and contorta pine, is a common tree in western North America. It is common near the ocean shore and in dry montane forests to the subalpine, but is rare in lowland rain forests. Like all pines, it is an evergreen conifer.

Coulter pine species of plant, Coulter Pine

The Coulter pine or big-cone pine, Pinus coulteri, is a native of the coastal mountains of Southern California and northern Baja California (Mexico). Isolated groves are found as far north as the San Francisco Bay Area in Mt. Diablo State Park and Black Diamond Mines Regional Preserve. The species is named after Thomas Coulter, an Irish botanist and physician.

<i>Pinus brutia</i> species of plant

Pinus brutia is a pine native to the eastern Mediterranean region. The bulk of its range is in Turkey, but it also extends to southeastern-most Bulgaria, the East Aegean Islands of Aegean Sea, Crete, the Crimea, Iran, Georgia, Azerbaijan, northern Iraq, western Syria, Israel, north-west Jordan, Lebanon, and Cyprus. It generally occurs at low altitudes, mostly from sea level to 600 metres (2,000 ft), up to 1,200 metres (3,900 ft) in the south of its range.

<i>Abies concolor</i> species of fir tree, native to mountains of western North America

Abies concolor, the white fir, is a coniferous tree in the pine family Pinaceae. This tree is native to the mountains of western North America from the southern Cascade range in Oregon, south throughout California and into the Sierra de San Pedro Mártir in northern Baja California; west through parts of southern Idaho, to Wyoming; and south throughout the Colorado Plateau and southern Rocky Mountains in Utah and Colorado, and into the isolated mountain ranges of southern Arizona, New Mexico and northern Mexico. White fir live over 300-years and naturally occur at an elevation between 900–3,400 m (2,950–11,200 ft).

<i>Cupressus pigmaea</i> species of plant

Cupressus pigmaea, the Mendocino cypress or pygmy cypress, is a taxon of disputed status in the genus Cupressus endemic to certain coastal terraces and coastal mountain ranges of Mendocino and Sonoma Counties in northwestern California. It is a highly variable tree, and closely related to Cupressus goveniana, enough to sometimes be considered a subspecies of it.

<i>Lupinus nanus</i> species of plant

Lupinus nanus, is a species of lupine native to the western United States. It is found natively in California, Nevada, and on Steens Mountain in eastern Oregon. It tends to be found growing on slopes and in open or disturbed areas below 1300 meters. It grows 6 to 20 inches tall with blue flowers containing white or yellow spots. It is an annual plant that blooms in the months of March, April and May. It contains anagyrine and is considered toxic if directly ingested. Among the biologically active chemicals found in the plant are genistein, 2'-hydroxygenistein, luteone and wighteone.

<i>Acer glabrum</i> species of plant

Acer glabrum is a species of maple native to western North America, from southeastern Alaska, British Columbia and western Alberta, east to western Nebraska, and south through Washington, Oregon, Idaho, Montana and Colorado to California, Arizona and New Mexico.

<i>Sambucus racemosa</i> Species of plant

Sambucus racemosa is a species of elderberry known by the common names red elderberry and red-berried elder.

<i>Ceanothus prostratus</i> species of plant

Ceanothus prostratus is a species of shrub in the family Rhamnaceae. Common names include prostrate ceanothus, pinemat, and mahala mat. It is native to the Pacific Northwest of the United States where it grows in coniferous forests and open plateaus.

<i>Chrysothamnus viscidiflorus</i> species of plant

Chrysothamnus viscidiflorus is a species of shrub in the daisy family of the Americas known by the common names yellow rabbitbrush and green rabbitbrush.


  1. Farjon, A. (2013). "Pinus ponderosa". IUCN Red List of Threatened Species . IUCN. 2013: e.T42401A2977432. doi: 10.2305/IUCN.UK.2013-1.RLTS.T42401A2977432.en .
  2. "Pinus ponderosa". Natural Resources Conservation Service PLANTS Database. USDA . Retrieved 31 January 2016; with distribution map.
  3. Moore, Gerry; Kershner, Bruce; Tufts, Craig; Mathews, Daniel; Nelson, Gil; Spellenberg, Richard; Thieret, John W.; Purinton, Terry; Block, Andrew (2008). National Wildlife Federation Field Guide to Trees of North America. New York, New York: Sterling. p. 89. ISBN   978-1-4027-3875-3.
  4. "BSBI List 2007". Botanical Society of Britain and Ireland. Archived from the original (xls) on 2015-01-25. Retrieved 2014-10-17.
  5. 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,
  6. Lauria, F. (1996). The identity of Pinus ponderosa Douglas ex C. Lawson (Pinaceae). Linzer Biologische Beitraege.
  7. The agriculturist's manual: being a familiar description of agricultural plants cultivated in Europe. Edinburgh U.K.: William Blackwood and Sons. 1836.
  8. Dickson, Tom. "Ponderosa Pine". Montana Outdoors. Montana Fish, Wildlife & Parks. Retrieved February 18, 2015.
  9. 1 2 3 4 Callaham, Robert Z. (September 2013). "Pinus ponderosa: A Taxonomic Review with Five Subspecies in the United States" (PDF). USDA Forest Service. PSW RP-264.
  10. 1 2 3 Callaham, Robert Z. (September 2013). "Pinus ponderosa: Geographic Races and Subspecies Based on Morphological Variation" (PDF). USDA Forest Service. PSW RP-265.
  11. Eckenwalder, James (2009). Conifers of the World. Portland, Oregon: Timber Press. ISBN   978-0-88192-974-4.
  12. Smith, Richard H. (1977). Monoterpenes of ponderosa pine in Western United States. USDA Forest Service. Tech. Bull. 1532.
  13. 1 2 Schoenherr, Allan A. (1995). A Natural History of California. University of California Press. p. 111.
  14. Kricher, John C (1998). A field guide to Rocky Mountain and southwest forests. Houghton Mifflin. p. 194.
  15. Kricher, John C. (1998). A field guide to California and Pacific Northwest forests. Houghton Mifflin. p. 107.
  16. "Pacific ponderosa pine". National Register of Big Trees. American Forests.
  17. Earle, Christopher J., ed. (2018). "Pinus ponderosa subsp. benthamiana". The Gymnosperm Database. Retrieved January 9, 2018.
  18. Fattig, Paul (January 23, 2011). "Tallest of the tall". Mail Tribune. Medford, Oregon. Retrieved January 27, 2011.
  19. Finkbeiner, Ann (May 31, 2013). "How Do We Know Nuclear Bombs Blow Down Forests?". Retrieved May 31, 2013.
  20. Meierhenry, Mark (March 2008). "The Old Growth Pines". South Dakota Magazine .
  21. Perry, JP Jr. (1991). Pines of Mexico and Central America. Portland, Oregon: Timber Press.
  22. Oliver, William W; Ryker, Russell A (1990). "Pinus ponderosa". In Burns, Russell M.; Honkala, Barbara H. (eds.). Conifers. Silvics of North America. Washington, D.C.: United States Forest Service (USFS), United States Department of Agriculture (USDA). 1. Retrieved 2020-03-12 via Southern Research Station (
  23. Stecker, Tiffany; ClimateWire (March 22, 2013). "U.S. Starts Massive Forest-Thinning Project". Scientific American. Retrieved April 19, 2014.
  24. Furniss, RL; Carolin, VM (1977). Western Forest Insects. US Department of Agriculture Forest Service. p. 177. Miscellaneous Publication 1339.
  25. Peattie, Donald Culross (1953). A Natural History of Western Trees. New York: Bonanza Books. pp. 83–84, 86.
  26. 1 2 Patterson, Patricia A. (1985). Field Guide to the Forest Plants of Northern Idaho (PDF). United States Department of Agriculture Forest Service. p. 20.
  27. "Pinus ponderosa subsp. brachyptera". Natural Resources Conservation Service PLANTS Database. USDA; with distribution map.
  28. "Pinus ponderosa, ponderosa pine". Catalog of the Woody Plants of Oklahoma. Oklahoma Biological Survey.
  29. "Arizona Mountains forests". Terrestrial Ecoregions. World Wildlife Fund.
  30. 1 2 Jepson Flora Project (ed.). "Pinus ponderosa var. pacifica". Jepson eFlora. The Jepson Herbarium, University of California, Berkeley . Retrieved January 9, 2018.
  31. "Pinus ponderosa var. pacifica". Calflora: Information on California plants for education, research and conservation, with data contributed by public and private institutions and individuals, including the Consortium of California Herbaria. Berkeley, California: The Calflora Database via
  32. "Pinus ponderosa var. ponderosa". Calflora: Information on California plants for education, research and conservation, with data contributed by public and private institutions and individuals, including the Consortium of California Herbaria. Berkeley, California: The Calflora Database via
  33. Jepson Flora Project (ed.). "Pinus ponderosa subsp. ponderosa". Jepson eFlora. The Jepson Herbarium, University of California, Berkeley . Retrieved January 9, 2018.
  34. "Pinus ponderosa var. ponderosa". Natural Resources Conservation Service PLANTS Database. USDA; with distribution map.
  35. "Pinus ponderosa var. scopulorum". Natural Resources Conservation Service PLANTS Database. USDA; with distribution map.
  36. 1 2 "Pinus ponderosa var. washoensis". Calflora: Information on California plants for education, research and conservation, with data contributed by public and private institutions and individuals, including the Consortium of California Herbaria. Berkeley, California: The Calflora Database via
  37. 1 2 Jepson Flora Project (ed.). "Pinus ponderosa var. washoensis". Jepson eFlora. The Jepson Herbarium, University of California, Berkeley . Retrieved January 9, 2018.
  38. 1 2 "Pinus ponderosa var. washoensis". Natural Resources Conservation Service PLANTS Database. USDA; with distribution map.
  39. Critchfield, WB; Little, EL (1966). Geographic distribution of the pines of the world. USDA Forest Service. Miscellaneous Publication 991, p. 16 (Map 47).
  40. Haller, JR (1961). "Some recent observations on ponderosa, Jeffrey, and Washoe pines in northeastern California". Madroño. 16: 126–132.
  41. Haller, JR (1965). "Pinus washoensis: taxonomic and evolutionary implications". American Journal of Botany. 52 (6): 646. JSTOR   2440143.
  42. Lauria, F (1997). "The taxonomic status of (Pinus washoensis) H. Mason & Stockw". Annalen des Naturhistorischen Museums in Wien. 99B: 655–671.
  43. Ryan, Catherine (March 19, 2012). "Loggers give unique Oregon ponderosa pine a lifeline". High Country News. Paonia, Colorado. Retrieved March 28, 2012.
  44. Smith, R. H. (1981). "Variation in cone color of immature ponderosa pine (Pinaceae) in northern California and southern Oregon". Madroño 28: 272–275.
  45. "Ponderosa Pine: Montana State Tree". State Symbols USA. Retrieved 13 February 2020.
  • Chase, J. Smeaton (1911). Cone-bearing Trees of the California Mountains. Chicago, Illinois: A. C. McClurg & Co. p. 99. LCCN   11004975. OCLC   3477527. LCC   QK495.C75 C4, with illustrations by Carl EytelKurut, Gary F. (2009), "Carl Eytel: Southern California Desert Artist", California State Library Foundation, Bulletin No. 95, pp. 17-20 (PDF), retrieved November 13, 2011
  • Conifer Specialist Group (1998). "Pinus ponderosa". IUCN Red List of Threatened Species . IUCN. 1998. Retrieved May 12, 2006.
  • Conkle, MT; Critchfield, WB (1988). "Genetic variation and hybridization of ponderosa pine". In Baumgartner, DM; Lotan, JE (eds.). 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.
  • Farjon, A (2005). Pines (2nd ed.). Leiden & Boston: Brill. ISBN   90-04-13916-8.
  • Haller, JR (1962). Variation and hybridization in ponderosa and Jeffrey pines. University of California Publications in Botany. 34. pp. 123–166.
  • Haller, JR (1965). "The role of 2-needle fascicles in the adaptation and evolution of ponderosa pine". Brittonia. 17 (4): 354–382. doi:10.2307/2805029. JSTOR   2805029.
  • Haller, JR; Vivrette, NJ (2011). "Ponderosa pine revisited". Aliso. 29 (1): 53–57. doi: 10.5642/aliso.20112901.07 .
  • Lauria, F (1991). "Taxonomy, systematics, and phylogeny of Pinus subsection Ponderosae Loudon (Pinaceae). Alternative concepts". Linzer Biol. Beitr. 23 (1): 129–202.
  • Lauria, F (1996). "The identity of Pinus ponderosa Douglas ex C.Lawson (Pinaceae)". Linzer Biol. Beitr. 28 (2): 999–1052.
  • Lauria, F (1996). "Typification of Pinus benthamiana Hartw. (Pinaceae), a taxon deserving renewed botanical examination". Ann. Naturhist. Mus. Wien. 98 (B Suppl): 427–446.
  • Mirov, NT (1929). "Chemical analysis of the oleoresins as a means of distinguishing Jeffrey pine and western yellow pine". Journal of Forestry. 27: 176–187.
  • Van Haverbeke, DF (1986). Genetic variation in ponderosa pine: A 15-Year Test of provenances in the Great Plains. USDA Forest Service. Research Paper RM-265.
  • Wagener, WW (1960). "A comment on cold susceptibility of ponderosa and Jeffrey pines". Madroño. 15: 217–219.