Editing Pinus flexilis

{{Short description|North American species of pine tree}}
{{Speciesbox
| name = Limber pine
| image = 2013-06-27 10 20 11 Limber Pine on Spruce Mountain, Nevada.jpg
| image_alt = 
| image_caption = Limber pine on [[Spruce Mountain (Nevada)|Spruce Mountain]], [[Nevada]]
| status = LC
| status_system = IUCN3.1
| status_ref = <ref name="iucn status 19 November 2021">{{cite iucn |author=Schoettle, A. |author2=Stritch, L. |date=2013 |title=''Pinus flexilis'' |volume=2013 |page=e.T42363A2975338 |doi=10.2305/IUCN.UK.2013-1.RLTS.T42363A2975338.en |access-date=19 November 2021}}</ref>
| status2 = {{TNCStatus}}
| status2_system = TNC
| status2_ref = <ref name="NatureServe">{{Cite NatureServe |date=6 December 2024 |id=2.140758 |title=''Pinus flexilis'' |access-date=8 December 2024}}</ref>
| genus = Pinus
| parent = Pinus subsect. Strobus
| display_parents = 3
| species = flexilis
| authority = [[Edwin James (scientist)|E.James]], 1824
| range_map = Pinus flexilis range map 1.png
| range_map_caption = Natural range
| synonyms_ref = <ref name="POWO">{{cite POWO |id=262945-1 |title=''Pinus flexilis'' E.James |access-date=20 October 2024}}</ref>
| synonyms = {{Species list
 | Apinus flexilis | (E.James) [[Rydb.]] (1905)
 | Pinus cembra var. flexilis | (E.James) F.Sanders (1874)
 | Pinus lambertiana var. brevifolia | [[Hook.]] (1838)
 | Pinus novaemexicana | P.Landry (1989)
 }}
}}

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

A limber pine in [[Eagle Cap Wilderness]], [[Oregon]], has been documented as over 2,000 years old, and another one was confirmed at 1,140 years old.<ref>{{cite web|url=http://www.opb.org/programs/ofg/segments/view/1739|title=Old Tree|year=2010|work=[[Oregon Field Guide]]|access-date=2010-02-21}}</ref><ref>{{cite news |last=Richard |first=Terry |url=http://blog.oregonlive.com/terryrichard/2012/09/ancient_limber_pine_likely_ore.html |title=Ancient limber pine, likely Oregon's oldest living tree, draws twin brothers to Wallowas quest (photo essay, video) |work=[[The Oregonian]] |date=September 24, 2012 |access-date=2015-02-18 }}</ref>  Another candidate for the oldest limber pine was identified in 2006 near the [[Alta Ski Area]] in Utah; called "Twister", the tree was confirmed to be at least 1,700 years old and thought to be even older.<ref>{{cite news |url=http://magazine.byu.edu/?act=view&a=1986 |title=Stay Flexible, Grow Old |work=[[BYU Magazine]] |date=Spring 2007 |access-date=2015-02-18 }}</ref>

== Description ==
Its pliant branches gives it the common name "limber" and specific epithet ''flexilis''. Its needles are about {{Convert|8|cm|sp=us|frac=4}} long and a dark, blueish green.<ref name=":0">{{Cite book |last1=Arno |first1=Stephen F. |url=https://www.worldcat.org/oclc/1141235469 |title=Northwest Trees: Identifying & Understanding the Region's Native Trees |last2=Hammerly |first2=Ramona P. |publisher=[[Mountaineers Books]] |year=2020 |isbn=978-1-68051-329-5 |edition=field guide |location=Seattle |pages=26, 43–49 |language=en |oclc=1141235469 |orig-date=1977}}</ref> Its bark is heavily creased and dark grey. Its pale wood is lightweight and soft.

''Pinus flexilis'' is typically a high-elevation pine, often marking the tree line either on its own, or with [[whitebark pine]] (''Pinus albicaulis''), either of the [[bristlecone pine]]s, or [[lodgepole pine]] (''Pinus contorta''). In favorable conditions, it makes a tree to {{convert|20|m|ft|round=5|abbr=off}}, rarely {{convert|25|m|ft|round=5|abbr=on}} tall. On exposed tree line sites, mature trees are much smaller, reaching heights of only {{convert|5|-|10|m|ft|round=5|abbr=on|sp=us}}.<ref name="Moore2008">{{cite book |last1=Moore |first1=Gerry |title=National Wildlife Federation Field Guide to Trees of North America |last2=Kershner |first2=Bruce |last3=Tufts |first3=Craig |last4=Mathews |first4=Daniel |last5=Nelson |first5=Gil |last6=Spellenberg |first6=Richard |last7=Thieret |first7=John W. |last8=Purinton |first8=Terry |last9=Block |first9=Andrew |publisher=Sterling |year=2008 |isbn=978-1-4027-3875-3 |location=New York |page=81 |display-authors=4}}</ref>  In steeply-sloping, rocky, and windswept terrain in the Rocky Mountains of southern Alberta, limber pine is even more stunted, occurring in old stands where mature trees are consistently less than {{convert|3|m|ft|0|abbr=on}} in height.<ref>{{cite journal|last1=Letts|first1=M.G.|first2=K.N.|last2=Nakonechny|first3=K.E.|last3=Van Gaalen|first4=C.M.|last4=Smith|year=2009|url=http://people.uleth.ca/~matthew.letts/Letts%20et%20al%202009%20CJFR.pdf|title=Physiological acclimation of ''Pinus flexilis'' to drought stress on contrasting slope aspects in Waterton Lakes National Park, Alberta, Canada|journal=Canadian Journal of Forest Research|volume=39|issue=3|pages=629–641|doi=10.1139/X08-206|bibcode=2009CaJFR..39..629L |url-status=dead|archive-url=https://web.archive.org/web/20110716093742/http://people.uleth.ca/~matthew.letts/Letts%20et%20al%202009%20CJFR.pdf|archive-date=2011-07-16}}</ref>

One of the world's oldest living limber pine trees grows on the banks of the upper North Saskatchewan River at Whirlpool Point in Alberta.
Recent measurements give a maximum girth of 185". In 1986, a core sample 10&nbsp;cm was retrieved by two researchers who counted 400 rings.
Extrapolating this data gives an age close to 3,000 years.

{{gallery|mode=packed
|File:Pinus flexilis male cones.jpg|Male cones of a limber pine, eastern [[Sierra Nevada (U.S.)|Sierra Nevada]], California
|File:Limberpinecone.jpg|Limber pine cone from [[San Jacinto Mountains]]
}}

=== Similar species ===
''Pinus flexilis'' is a member of the [[Pinus classification|white pine]] group, ''[[Pinus]]'' subgenus ''[[Strobus]]'', and like all members of that group, the leaves ('needles') are in [[fascicle (botany)|fascicles]] (bundles) of five,<ref name=":0" /> with a deciduous sheath. This distinguishes it from the [[lodgepole pine]], with two needles per fascicle, and the bristlecone pines, which share five needles per fascicle but have a semi-persistent sheath.

==== ''Pinus albicaulis'' ====
Distinguishing limber pine from the related whitebark pine (''P. albicaulis''), also a white pine, is very much more difficult, and can only easily be done by the cones. In limber pine, the cones are {{convert|6-15|cm|in|frac=4|abbr=on}} long<ref name=":0" /> where the species overlap, green when immature, and open to release the seeds; the scales are not fragile. In whitebark pine, the cones are {{convert|4|-|7|cm|in|frac=4|abbr=on}} long, dark purple when immature, and do not open on drying, but are fragile and are pulled apart by birds to release the seeds.<ref>{{cite web |title=''Pinus'' subgenus ''Strobus'' |url=http://www.pinetum.org/cones/PNStrobus.htm |work=Michael P. Frank's Cone Collection |publisher=Arboretum de Villardebelle}}</ref> A useful clue is that whitebark pines almost never have intact old cones lying under them, whereas limber pines usually do.
<ref>{{cite web |last1=Roady |first1=Laura |title=Whitebark Pine |url=http://fwp.mt.gov/mtoutdoors/HTML/articles/portraits/whitebarkpine.htm |access-date=15 March 2015 |website=Montana Outdoors |publisher=Montana Fish, Wildlife & Parks}}</ref>

==== ''Pinus monticola'' ====
In the absence of cones, limber pine can also be hard to tell from [[Western white pine]] (''P. monticola'') where they occur together in the northern Rockies and the Sierra Nevada east slope. The most useful clue here is that limber pine needles are entire (smooth when rubbed gently in both directions), whereas Western white pine needles are finely serrated (feeling rough when rubbed gently from tip to base). Limber pine needles are also usually shorter, {{convert|4|-|7|cm|in|frac=4|abbr=on}} long, while western white pine needles are {{convert|5|-|10|cm|in|0|abbr=on}}, though the ranges overlap.

== Distribution ==
The largest part of the limber pine's range is in the [[Rocky Mountains]], from southwest [[Alberta]]<ref name=":0" /> and southeastern [[British Columbia]] south through [[Colorado]] and [[New Mexico]] into the northern states of [[Mexico]]. It is also found through the [[Great Basin]]<ref name=":0" /> states of [[Nevada]] and [[Utah]], in the eastern [[Sierra Nevada (U.S.)|Sierra Nevada]] and [[White Mountains (California)|White Mountains]] of [[Northern California]], and in the [[San Bernardino Mountains|San Bernardino]] and [[San Gabriel Mountains]] of the [[Transverse Ranges]] in [[Southern California]]. Continuing south the species is found in the [[San Jacinto Mountains]], [[Santa Rosa Mountains (California)|Santa Rosa Mountains]],{{citation needed|date=April 2014}} and [[Hot Springs Mountain]]{{citation needed|date=April 2014}} of the [[Peninsular Ranges]]. There are small disjunct populations in eastern [[Oregon]], in western [[North Dakota]] and [[Nebraska]],<ref name="silvics">{{Silvics|volume=1|genus=Pinus|species=flexilis|first=Robert|last=Steele}}</ref> and in the [[Black Hills]] of [[South Dakota]].<ref name="fna">{{EFloras|1|233500936|Pinus flexilis|family=Pinaceae|first=Robert|last=Kral}}</ref><ref name="Moore2008" /> It is found at a wide range of altitudes depending on the latitude, from {{convert|850|to|3810|m|ft|abbr=on|sp=us}}. In the northern half of its range, it grows in the [[montane zone]] near the lower [[tree line]]; in the middle of its range between the [[45th parallel north|45th]] and [[40th parallel north|40th parallels]], it grows on windswept sites in the montane and [[subalpine zone]]s; and in the southern part of its range, it grows mainly at high elevations in the subalpine zone near the upper tree line.<ref name="silvics" /> It can more often be found at the outer fringes of a forest than in the forest itself.<ref name=":0" />

== Ecology ==
''Pinus flexilis'' is an important source of food for several species, including [[pine squirrel|red squirrels]] and [[Clark's nutcracker]]s, the latter being an important distributor of seeds.<ref name="Siepielski 611–618">{{Cite journal |last1=Siepielski |first1=A. M. |last2=Benkman |first2=C. W. |date=June 2007 |title=Selection by a predispersal seed predator constrains the evolution of avian seed dispersal in pines |journal=Functional Ecology |language=en |volume=21 |issue=3 |pages=611–618 |doi=10.1111/j.1365-2435.2007.01261.x |issn=0269-8463|doi-access=free |bibcode=2007FuEco..21..611S }}</ref><ref name=":0" /> There is evidence that limber pines co-evolved with Clark's nutcrackers, which are the primary dispersers of the seeds.<ref>{{Cite journal |last1=Siepielski |first1=Adam M. |last2=Benkman |first2=Craig W. |title=Convergent Patterns in the Selection Mosaic for Two North American Bird-Dispersed Pines |date=May 2007 |url=http://doi.wiley.com/10.1890/06-0929 |journal=Ecological Monographs |language=en |volume=77 |issue=2 |pages=203–220 |doi=10.1890/06-0929 |bibcode=2007EcoM...77..203S |issn=0012-9615|url-access=subscription }}</ref><ref name="Siepielski 611–618"/><ref>{{Cite journal |last1=Siepielski |first1=Adam M. |last2=Benkman |first2=Craig W. |title=Seed Predation and Selection Exerted by a Seed Predator Influence Subalpine Tree Densities |date=October 2008 |url=http://doi.wiley.com/10.1890/08-0072.1 |journal=Ecology |language=en |volume=89 |issue=10 |pages=2960–2966 |doi=10.1890/08-0072.1 |pmid=18959333 |bibcode=2008Ecol...89.2960S |issn=0012-9658|url-access=subscription }}</ref> In a relic, low elevation population, seeds are also dispersed by small rodents.<ref>{{Cite journal |last1=Tomback |first1=Diana F. |author1-link=Diana Tomback|last2=Schoettle |first2=Anna W. |last3=Chevalier |first3=Kristen E. |last4=Jones |first4=Cheri A. |date=2005-01-01 |title=Life on the edge for limber pine: Seed dispersal within a peripheral population |url=https://doi.org/10.2980/i1195-6860-12-4-519.1 |journal=Écoscience |volume=12 |issue=4 |pages=519–529 |doi=10.2980/i1195-6860-12-4-519.1 |bibcode=2005Ecosc..12..519T |s2cid=86330607 |issn=1195-6860|url-access=subscription }}</ref> [[American black bear]]s and [[grizzly bear]]s may raid squirrel caches for limber pine nuts.<ref name=":0" /> Squirrels, [[Northern flicker]]s, and [[mountain bluebird]]s often nest in the trees. There is some evidence that ''P. flexilis'' has a symbiotic relationship with nitrogen-fixing bacteria that inhabit the needles.<ref>{{Cite journal|last1=Moyes|first1=Andrew B.|last2=Kueppers|first2=Lara M.|last3=Pett-Ridge|first3=Jennifer|last4=Carper|first4=Dana L.|last5=Vandehey|first5=Nick|last6=O'Neil|first6=James|last7=Frank|first7=A. Carolin|date=2016-04-01|title=Evidence for foliar endophytic nitrogen fixation in a widely distributed subalpine conifer|journal=New Phytologist|language=en|volume=210|issue=2|pages=657–668|doi=10.1111/nph.13850|pmid=27000956|issn=1469-8137|url=https://cloudfront.escholarship.org/dist/prd/content/qt4s82s0d8/qt4s82s0d8.pdf?t=p84gde|doi-access=free|bibcode=2016NewPh.210..657M }}</ref>

The species is generally [[shade tolerant]] and resistant to fire, but does not thrive in dense habitats, instead occurring in areas relatively hostile to other species.<ref>{{Cite journal |last1=Rebertus |first1=A. J. |last2=Burns |first2=B. R. |last3=Veblen |first3=T. T. |date=August 1991 |title=Stand dynamics of Pinus flexilis -dominated subalpine forests in the Colorado Front Range |url=http://doi.wiley.com/10.2307/3236026 |journal=Journal of Vegetation Science |language=en |volume=2 |issue=4 |pages=445–458 |doi=10.2307/3236026|jstor=3236026 |bibcode=1991JVegS...2..445R |url-access=subscription }}</ref><ref name=":0" />

=== Threats ===
Limber pine is susceptible to [[white pine blister rust]],<ref name=":0" /> caused by ''Cronartium ribicola'', a fungus that was introduced accidentally from Europe. Limber pine mortality is high in many areas throughout its range, except [[Arizona]], where it has not yet been found. However, there is little hope of controlling the blister rust in existing trees. Research is under way, locating and breeding from the occasional naturally resistant limber pines, and by studying the resistance mechanisms of the European and Asian white pines (e.g. [[Swiss pine]], [[Macedonian pine]]), which are strongly resistant to the disease.

The tree has also been damaged by [[bark beetle]] epidemics, particularly at drought-affected low elevations.<ref name=":0" />

== Cultivation ==
The popular [[cultivar]] ''P. flexilis'' 'Vanderwolf's Pyramid' is widely available as an [[ornamental tree]] for [[garden]]s. 'Vanderwolf's Pyramid' derives from ''P. reflexa'', though it is usually listed in nursery catalogs under ''P. flexilis''.

The Southwestern white pine is popular as a windbreak tree or an ornamental tree due to its drought tolerance.  It is also grown as a [[Christmas tree]], liked for the soft needles but with stiffer branches than an [[Eastern white pine]].

==Uses==
The large seeds are edible,<ref>{{cite book |last=Whitney |first=Stephen |title=Western Forests (The Audubon Society Nature Guides) |date=1985 |publisher=Knopf |location=New York |isbn=0-394-73127-1 |pages=[https://archive.org/details/westernforests00whit/page/407 407–08] |url=https://archive.org/details/westernforests00whit/page/407 }}</ref> and were reportedly consumed by Native Americans in Montana.<ref name=":0" />

== See also ==
* [[Burmis Tree]]

== References ==
{{Reflist}}

=== Further reading ===
* {{cite book | last1 = Chase| first1 = J. Smeaton| author-link1 = J. Smeaton Chase|others=[[Carl Eytel|Eytel, Carl]] (illustrations)|title = Cone-bearing Trees of the California Mountains |chapter=''Pinus flexilis'' (Limber-pine, White-pine)|chapter-url = https://archive.org/details/conebearingtrees00chas/page/48/mode/2up| location = Chicago | publisher = [[A.C. McClurg & Co.]] | pages = 48–50 |year=1911 | oclc = 3477527|lccn=11004975}}
* {{cite book |last1=Schoettle |first1=Anna |display-authors=etal |title=Proactive Limber Pine Conservation for the Greater Rocky Mountain National Park Area |date=February 2019 |publisher=U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station |location=Fort Collins, CO |url=https://purl.fdlp.gov/GPO/gpo116774 |access-date=7 March 2019}}

== External links ==
{{sister project links|display=''Pinus flexilis''|auto=1}}
* [http://www.conifers.org/pi/pin/flexilis.htm Gymnosperm Database: ''Pinus flexilis'']
* [http://ucjeps.berkeley.edu/cgi-bin/get_cpn.pl?38277 ''Pinus flexilis'', Jepson Manual]
* [http://www.pinetum.org/cones/PNStrobus.htm ''Pinus flexilis'' cone photos]
* [http://www.fs.fed.us/rm/highelevationwhitepines/trees/limber.htm High Elevation White Pine Educational Website: ''Pinus flexilis'']
* [https://web.archive.org/web/20140508151347/http://www.opb.org/programs/ofg/segment/old-tree/ Old Tree]  Documentary produced by [[Oregon Field Guide]]

{{Taxonbar|from=Q594993}}
{{Authority control}}

[[Category:Pinus|flexilis]]
[[Category:Flora of the Southwestern United States]]
[[Category:Flora of Alberta]]
[[Category:Flora of British Columbia]]
[[Category:Flora of Colorado]]
[[Category:Flora of Idaho]]
[[Category:Flora of Montana]]
[[Category:Flora of New Mexico]]
[[Category:Flora of North Dakota]]
[[Category:Flora of Oregon]]
[[Category:Flora of South Dakota]]
[[Category:Flora of Wyoming]]
[[Category:Trees of Northern America]]
[[Category:Plants described in 1824]]
[[Category:Taxa named by Edwin James]]