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Pinus flexilis
E.James
Limber Pine
Pinaceae
Pinus flexilis is a coniferous tree in the family Pinaceae. It is native to mountainous areas of western North America, and is commonly grown as an ornamental.
Description
Pinus flexilis is a tree that grows up to 26 m, with a trunk that grows up to 2 m in diameter. The tree forms a round to conic crown, with spreading to ascending branches. Leaves are flexible, pointed, and finely toothed, 3 to 7 cm long and 1 to 1.5 mm thick in bundles of 5. They are dark green with pale bands (which are stomata), and persist on the tree for 5 to 6 years. The sheaths are at least 1 to 1.5 cm long and are not persistent. Buds are ovoid, light reddish-brown, about 9 to 10 mm long and are resinous. The bark is gray, smooth becoming cracked into plates and ridges with age. Male cones are small and ellipsoid to cylindric, pale red or yellow, about 15 mm long. Seed cones are 7 to 15 cm long, egg-shaped and wider when open, short-stalk or stalkless. They are symmetrical, straw-colored, and have scales that are thick and smooth (i.e. without prickles). These cones ripen in 2 years, open, then fall from the tree after releasing their seeds. Seeds are about 10 to 15 mm wide, brown, egg-shaped, and mostly without wings (FNAEC 1993).
The species reportedly hybridizes with Pinus strobiformis (FNAEC 1993). Its branchlets and twigs are quite flexible, hence both the common and scientific names (MBG).
The species reportedly hybridizes with Pinus strobiformis (FNAEC 1993). Its branchlets and twigs are quite flexible, hence both the common and scientific names (MBG).
Uses
Note: Please see the disclaimer regarding any information about medical or edible uses.
Pinus flexilis is often grown as an ornamental. It prefers well-drained soil, medium moisture, and full sun, but is adaptable and grows in drier, rockier climates. It grows in USDA zones 4 to 7 (MBG). The tree’s wood is of little use because it is relatively inaccessible and often grows into a crooked form; it finds some use as firewood (Schoettle and Stritch 2013).
Distribution
Pinus flexilis is found in mountains often close to timberline, typically at an altitude of 1500 to 3600 m. It is native to southwestern Alberta, southeastern British Columbia, Montana, Idaho, Wyoming, Colorado, Utah, Nevada, California, and New Mexico, with isolated populations in North Dakota, South Dakota, Oregon, Nebraska, and Arizona (FNAEC 1993).
Status
The main variety, Pinus flexilis var. flexilis, is listed on the IUCN Red List as "Least Concern". However, its population is declining from white pine blister rust (Cronartium ribicola) and mountain pine beetle (Dendroctonus ponderosae), which both attack this tree and related trees. Since the declines have not been large-scale enough to wipe out entire populations of the species, and species’ range has not declined in past years, the species is still considered to be of “Least Concern”. Variety reflexa, on the other hand, is rare and has only been found in five locations; therefore it is listed as “Near Threatened” (Schoettle and Stritch 2013).
References
MBG (Missouri Botanical Garden), Pinus flexilis. Plant Finder. [accessed 2019 Jul 7]. http://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=l750
FNAEC (Flora of North America Editorial Committee), editor. 1993. Flora of North America, north of Mexico. Volume 2: Pteridophytes and Gymnosperms. New York: Oxford University Press.
Schoettle, A., and Stritch, L. 2013. Pinus flexilis. The IUCN Red List of Threatened Species. http://dx.doi.org/10.2305/IUCN.UK.2013-1.RLTS.T42363A2975338.en.
FNAEC (Flora of North America Editorial Committee), editor. 1993. Flora of North America, north of Mexico. Volume 2: Pteridophytes and Gymnosperms. New York: Oxford University Press.
Schoettle, A., and Stritch, L. 2013. Pinus flexilis. The IUCN Red List of Threatened Species. http://dx.doi.org/10.2305/IUCN.UK.2013-1.RLTS.T42363A2975338.en.
Description
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