Limber Pine
463797
221705776
2008-06-25T18:41:19Z
Aille
1737570
{{Taxobox
| name = Limber Pine
| status = LR/lc
| image = Pinus flexilis.jpg
| image_width = 240px
| image_caption = Cultivated Specimen<br>[[Morton Arboretum]] acc. 599-72*1
| regnum = [[Plant]]ae
| divisio = [[Pinophyta]]
| classis = [[Pinophyta|Pinopsida]]
| ordo = [[Pinales]]
| familia = [[Pinaceae]]
| genus = ''[[Pine|Pinus]]''
| subgenus = ''[[Pinus classification|Strobus]]''
| species = '''''P. flexilis'''''
| binomial = ''Pinus flexilis''
| binomial_authority = E.James
}}
The '''Limber Pine''' (''Pinus flexilis''; family [[Pinaceae]]) is a species of [[pine]] [[tree]] that occurs in the mountains of the [[Western United States]] and [[Canada]], specifically the [[subalpine]] areas of the [[Rocky Mountains]] from southwest [[Alberta]] south to the [[Mexico|Mexican]] border; the [[Great Basin]] mountains of [[Nevada]] and [[Utah]]; and the [[White Mountains (California)|White Mountains]], the east slope of the [[Sierra Nevada (U.S.)|Sierra Nevada]] and the [[San Bernardino Mountains]] in [[California]] with a small disjunct population in the [[Black Hills]] of [[South Dakota]].
[[Image:Limberpinecone.jpg|thumb|left|150px|Limber pine cone from [[San Jacinto Mountains]]]]
It is typically a high-elevation pine, often marking the [[tree line]] either on its own, or with [[Whitebark Pine]], either of the [[bristlecone pine]]s, or [[Lodgepole Pine]]. In favourable conditions, it makes a tree to 20 m, rarely 25 m tall, but on exposed tree line sites only 5-10 m tall.
Limber Pine 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 fascicles (bundles) of five, with a deciduous sheath. This distinguishes it from the [[Lodgepole Pine]], with two needles per fascicle, and the [[bristlecone pine]]s, which share five needles per fascicle but have a semi-persistent sheath.
Distinguishing Limber Pine from the related [[Whitebark Pine]], also a white pine, is very much more difficult, and can only easily be done by the cones. In Limber Pine, the cones are 6-12 cm long where the species overlap, green when immature, and open to release the seeds; the scales are not fragile. In Whitebark Pine, the cones are 4-7 cm long, dark purple when immature, and do not open on drying, but are fragile and are pulled apart by birds (see below) to release the seeds. A useful clue resulting is that Whitebark Pines almost never have intact old cones lying under them, whereas Limber Pines usually do.
[[Image:Limber pine quaking aspen.JPG|thumb|left|Limber Pine in the [[Toiyabe Range]], central [[Nevada]]]]In the absence of cones, Limber Pine can also be hard to tell from [[Western White Pine]] 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, 4-7 cm long, to Western White Pine's 5-10 cm (though note the overlap).
In [[Arizona]] and [[New Mexico]], Limber Pine differs from the populations further north. These populations, often known as '''Southwestern White Pine''', are sometimes treated as a variety, '''''Pinus flexilis'' var. ''reflexa''''', but more often as a distinct species, either (accurately) under the name '''''Pinus reflexa''''', or (through confusion with the Mexican [[Chihuahua White Pine]]), erroneously under the name ''Pinus strobiformis'' (which correctly applies to the Mexican species). The Southwestern White Pine differs from typical Limber Pine in being a larger tree, to 25-35 m tall, with longer needles, 6-11 cm long, which have strongly white stomatal bands on the inner faces of the needles (inconspicuous in the type), and are slightly serrated towards the tips of the needles. The cones are also larger, typically 10-20 cm long. It differs from true Mexican ''Pinus strobiformis'' in that the needles are not fully serrated, and the cones being smaller (15-25 cm in ''P. strobiformis''), the cone scales shorter and the seeds smaller. It is possible that ''Pinus reflexa'' is a natural hybrid between ''Pinus flexilis'' and ''Pinus strobiformis''. Type localities of the three taxa are:<br>
''Pinus flexilis'': [[Pikes Peak]], [[Colorado]]<br>
''Pinus reflexa'': [[Santa Catalina Mountains]] 40 km east of [[Tucson]], [[Arizona]] <br>
''Pinus strobiformis'': Cusihuiráchic, 90 km southwest of [[Chihuahua, Chihuahua|the city of Chihuahua]], in the south of the Mexican state of [[Chihuahua]]
[[Image:Limber Pine at Craters of the Moon National Monument.jpeg|thumb|right|Limber pine in the [[Craters of the Moon National Monument and Preserve|Craters of the Moon National Monument]], [[Idaho]]]]
Limber Pine is an important source of food for several species, including [[Pine squirrel|Red Squirrel]]s and [[Clark's Nutcracker]]s. [[American Black Bear]]s may raid squirrel caches for Limber Pine nuts. Squirrels, [[Northern Flicker]]s, and [[Mountain Bluebird]]s often nest in the trees.
Unfortunately, Limber Pine is afflicted with [[White Pine Blister Rust]] (''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 no known way 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 popular [[cultivar]] ''''Vanderwolf's Pyramid<nowiki>'</nowiki>''', widely sold as an ornamental tree, derives from ''Pinus reflexa'', though it is usually listed in nursery catalogs under ''Pinus flexilis''.
==References==
* {{IUCN2006|assessors=Conifer Specialist Group|year=1998|id=42363|title=Pinus flexilis|downloaded=12 May 2006}}
==External links==
*[http://www.pinetum.org/cones/PNStrobus.htm ''Pinus flexilis'' cone pics; compare also ''Pinus reflexa'' and ''Pinus strobiformis'' (scroll ¼ way down page)]
*[http://www.conifers.org/pi/pin/flexilis.htm Gymnosperm Database: ''Pinus flexilis'']
*[http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=233500936 Flora of North America, profile and map: ''Pinus flexilis'']
*[http://plants.usda.gov/java/profile?symbol=PIFL2 USDA Plants Profile: ''Pinus flexilis'']
{{DEFAULTSORT:Pine, Limber}}
[[Category:Pinaceae]]
[[Category:Trees of the Western United States]]
[[Category:Trees of South Dakota]]
[[Category:Trees of Alberta]]
[[Category:Trees of British Columbia]]
[[Category:Trees of California]]
[[Category:Trees of Chihuahua]]
[[Category:Trees of Coahuila]]
[[Category:Trees of Nuevo León]]
[[Category:Trees of Sonora]]
[[cs:Borovice ohebná]]
[[fr:Pin flexible]]
[[hu:Nevadai cirbolyafenyő]]
[[pl:Sosna giętka]]
[[pt:Pinus flexilis]]
[[vi:Thông Limber]]