Editing Pseudotsuga menziesii var. glauca

{{Short description|Variety of plants}}
{{Infraspeciesbox
| name = Rocky Mountain Douglas-fir
| image = Pseudotsuga glauca forest.jpg
| image_caption = Rocky Mountain Douglas-fir forest in [[Pike National Forest]], [[Colorado]] ([[United States]])
| genus  = Pseudotsuga
| species = menziesii
| species_link = Douglas fir
| varietas = glauca
| authority = (Mayr) Franco
| synonyms =
* ''Pseudotsuga menziesii'' var. ''caesia'' (Schwer.) Franco
* ''Pseudotsuga taxifolia'' var. ''caesia'' (Schwer.) Asch. & Graebn.
* ''Pseudotsuga taxifolia'' var. ''glauca'' (Beissn.) Sudw.
| synonyms_ref = <ref>{{GRIN|id=30192|name=Pseudotsuga menziesii var. glauca}}</ref>
}}
[[File:Pseudotsuga menziesii subsp. glauca kz02.jpg|thumb|''Pseudotsuga'' ''menziesii'' subsp'''.''' ''glauca'']]
'''''Pseudotsuga menziesii'' var. ''glauca''''', or '''Rocky Mountain Douglas-fir''', is an [[evergreen]] [[Pinophyta|conifer]] native to the interior [[mountain]]ous regions of western North America, from central [[British Columbia]] and southwest [[Alberta]] in Canada southward through the United States to the far north of Mexico.<ref>C. Michael Hogan (2008). ''Douglas-fir: "Pseudotsuga menzesii"'', GlobalTwitcher.com, ed. N. Stromberg {{cite web |url=http://globaltwitcher.auderis.se/artspec_information.asp?thingid=44736 |title=Douglas-fir (Pseudotsuga menziesii ) - - GlobalTwitcher.com |access-date=2009-06-04 |url-status=dead |archive-url=https://web.archive.org/web/20090604021155/http://globaltwitcher.auderis.se/artspec_information.asp?thingid=44736 |archive-date=2009-06-04 }}</ref> The range is continuous in the northern [[Rocky Mountains]] south to eastern [[Washington (state)|Washington]], eastern [[Oregon]], [[Idaho]], western and south-central [[Montana]] and western [[Wyoming]], but becomes discontinuous further south, confined to "[[sky island]]s" on the higher mountains in [[Utah]], [[Colorado]], [[Arizona]] and [[New Mexico]], with only very isolated small populations in eastern [[Nevada]], westernmost [[Texas]], and northern Mexico. It occurs from 600&nbsp;m altitude in the north of the range, up to 3,000&nbsp;m, rarely 3,200&nbsp;m, in the south. Further west towards the Pacific coast, it is replaced by the related [[coast Douglas-fir]] (''Pseudotsuga menziesii'' var. ''menziesii''), and to the south, it is replaced by [[Mexican Douglas-fir]] in high mountains as far south as [[Oaxaca (state)|Oaxaca]]. Some botanists have grouped [[Mexican Douglas-fir]] with ''P. menziesii'' var. ''glauca'',<ref name=little>{{cite journal | last1 = Little | first1 = E. L. | year = 1952 | title = The genus ''Pseudotsuga'' (Douglas-fir) in North America | journal = Leaflets of Western Botany | volume = 6 | pages = 181–198 }}</ref> but genetic<ref>{{cite journal|last=Gugger|first=Paul F.|author2=González-Rodríguez, Antonio|author3=Rodríguez-Correa, Hernando|author4=Sugita, Shinya|author-link5=Jeannine Cavender-Bares|author5=Cavender-Bares, Jeannine|title=Southward Pleistocene migration of Douglas-fir into Mexico: phylogeography, ecological niche modeling, and conservation of 'rear edge' populations|journal=New Phytologist|year=2011|volume=189|issue=4|pages=1185–1199|doi=10.1111/j.1469-8137.2010.03559.x|pmid=21118265|doi-access=free}}</ref> and morphological<ref>{{cite journal|last=Reyes-Hernández|first=VJ|author2=Vargas-Hernández JJ |author3=López-Upton J |author4=Vaquera-Huerta H |title=Phenotypic similarity among Mexican populations of ''Pseudotsuga'' Carr|journal=Agrociencia|year=2006|volume=40|issue=4|pages=545–556|url=http://www.colpos.mx/agrocien/Bimestral/2006/jul-ago/art-13.pdf}}</ref> evidence suggest that Mexican populations should be considered a different variety (''[[Pseudotsuga menziesii var. lindleyana]]'').<ref>{{cite web|last=Earle|first=C.J.|title=The Gymnosperm Database: ''Pseudotsuga lindleyana''|url=http://www.conifers.org/pi/Pseudotsuga_lindleyana.php|access-date=9 January 2018|url-status=dead|archive-url=https://web.archive.org/web/20120118104354/http://www.conifers.org/pi/Pseudotsuga_lindleyana.php|archive-date=18 January 2012}}</ref>

Rocky Mountain Douglas-fir is most commonly treated as a [[variety (biology)|variety]] (''Pseudotsuga menziesii'' var. ''glauca''),<ref name=little /><ref>{{cite web|title=Flora of North America|url=http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=233500996|access-date=12 January 2012}}</ref> but has also been called a [[subspecies]] (''Pseudotsuga menziesii'' subsp. ''glauca'')<ref name=newtrees>Grimshaw, J., & Bayton, R. (2009). ''New Trees''. International Dendrology Society / Kew. {{ISBN|978-1-84246-173-0}}.</ref> or more rarely (mainly in the past) a distinct [[species]] (''Pseudotsuga glauca'').<ref>Mayr, H. (1906). ''Fremdländische Wald- und Parkbäume für Europa'' [https://archive.org/stream/fremdlndischew00mayruoft#page/404/mode/2up p.404]. Berlin.</ref> The strong ecological and genetic differentiation with intergradation limited primarily to [[postglacial]] contact zones in [[British Columbia]]<ref name=li>{{cite journal|last=Li|first=P.|author2=Adams, W.T. |title=Rangewide patterns of allozyme variation in Douglas-fir|journal=Canadian Journal of Forest Research|year=1989|volume=19|issue=2|pages=149–161|doi=10.1139/x89-022}}</ref><ref name=gugger>{{cite journal|last=Gugger|first=Paul F. |author2=Sugita, Shinya |author3=Cavender-Bares, Jeannine|title=Phylogeography of Douglas-fir based on mitochondrial and chloroplast DNA sequences: testing hypotheses from the fossil record|journal=Molecular Ecology|year=2010|volume=19|issue=9|pages=1877–1897|doi=10.1111/j.1365-294X.2010.04622.x|pmid=20374486|bibcode=2010MolEc..19.1877G |s2cid=23254018 }}</ref> supports [[Infraspecific name (botany)|infraspecific]] groupings. Some botanists have further split Rocky Mountain Douglas-fir into two varieties,<ref>Dallimore, W., & Jackson, A. B. (1966). ''A Handbook of Coniferae and Ginkgoaceae'', 4th ed. Arnold, London.</ref> but these are not widely acknowledged and have only limited support from [[genetic testing]].<ref name=newtrees /><ref name=li /><ref name=gugger />

==Characteristics==
[[File:Pseudotsuga menziesii var. glauca young female cone - Keila.jpg|thumb|left|Young seed cone]]
Rocky Mountain Douglas-fir is a large [[tree]], typically reaching {{convert|35|–|45|m|abbr=on}} in height and {{convert|1|m|abbr=on}} in diameter, with exceptional specimens known to {{convert|67|m|abbr=on}} tall, and {{convert|2|m|abbr=on}} in diameter. It commonly lives more than 500 years and occasionally more than 1,200 years. The [[bark (biology)|bark]] on young trees is thin, smooth, gray, and covered with resin blisters. On mature trees, it is moderately thick ({{convert|3|–|6|cm|frac=4|abbr=on|disp=comma}}), furrowed and corky though much less so than coast Douglas-fir.

[[File:2013-07-14 09 27 54 Douglas fir foliage along Wheeler Peak Scenic Drive in Great Basin National Park, Nevada.jpg|thumb|Foliage]]
The shoots are brown to gray-brown, smooth, though not as smooth as [[fir]] shoots, and finely pubescent with scattered short hairs. The [[bud]]s are a distinctive narrow conic shape, {{convert|3|–|6|mm|frac=16|abbr=on}} long, with red-brown bud scales. The leaves are spirally arranged but slightly twisted at the base to be upswept above the shoot, needle-like, {{convert|2|–|3|cm|frac=4|abbr=on}} long, gray-green to blue-green above with a single broad [[stomata]]l patch, and with two whitish stomatal bands below.

The male ([[pollen]]) cones are {{convert|2|–|3|cm|frac=4|abbr=on}} long, and are typically restricted to, or more abundant on, lower branches. Pollen cones develop over 1 year and wind-dispersed pollen is released for several weeks in the spring.

[[Image:Pseudotsuga glauca cones.jpg|thumb|Rocky Mountain Douglas-fir cones<br/>Left: [[Shuswap Lake]], [[British Columbia]], Canada<br/>Right: [[Chiricahua Mountains]], [[Arizona]], U.S.]]

The mature female [[Conifer cone|seed cones]] are pendent, {{convert|4|–|7|cm|frac=4|abbr=on}} long, {{convert|2|cm|frac=4|abbr=on}} broad when closed, opening to {{convert|3|–|4|cm|frac=4|abbr=on}} broad. They are produced in spring, purple (sometimes green) at first, maturing orange-brown in the autumn 5–7 months later. The seeds are {{convert|5|–|6|mm|frac=16|abbr=on}} long and {{convert|3|–|4|mm|frac=16|abbr=on}} broad, with a {{convert|12|–|15|mm|frac=16|abbr=on}} wing. Both coast Douglas-fir and Rocky Mountain Douglas-fir produce abundant crops of seed approximately every 2–11&nbsp;years. Seed is produced annually except for about 1 year in any 4-to-5-year period.

==Growth==
[[File:Pseudotsuga menziesii Thompson-Nicola BC.jpg|thumb|right|Douglas-fir, [[British Columbia]]]]
Rocky Mountain Douglas-fir grows more slowly than coast Douglas-fir and is also much more cold tolerant. Tolerance of different environmental conditions varies among populations of Rocky Mountain Douglas-fir, especially among populations from the northern and southern Rockies.<ref>{{cite journal|last=Zhang|first=J.|author2=Marshall, J.D. |author3=Jaquish, B.C. |title=Genetic differentiation in carbon isotope discrimination and gas exchange in ''Pseudotsuga menziesii''|journal=Oecologia|year=1993|volume=93|issue=1|pages=80–87|doi=10.1007/BF00321195|pmid=28313778|bibcode=1993Oecol..93...80Z |s2cid=52833650 }}</ref>  However, even nearby populations can differ in cold hardiness.<ref>{{cite journal|last=Rehfeldt|first=G.E.|title=Ecological adaptations in Douglas-Fir (''Pseudotsuga menziesii'' var. ''glauca''): a synthesis|journal=Forest Ecology and Management|year=1989|volume=28|issue=3–4|pages=203–215|doi=10.1016/0378-1127(89)90004-2|bibcode=1989ForEM..28..203R |url=https://zenodo.org/record/1258535}}</ref>

[[Root]] morphology is variable, but when unimpeded, a [[taproot]] forms within several years. "Platelike" root morphologies occur where growth is impeded. The most prominent lateral roots begin in the 1st or 2nd year of growth. Most roots in surface soil are "long ropelike laterals of secondary and tertiary origin". Fine-root production is episodic in response to changing environmental conditions; the average lifespan of fine roots is usually between several days and several weeks.

Rocky Mountain Douglas-fir reaches reproductive maturity at 12–15 years. It has winged seeds that are dispersed primarily by wind and [[gravity]]. In western [[Montana]] clearcuts, seeds were dispersed up to {{convert|250|m|ft|abbr=on}} uphill from their source, but seedfall between {{convert|180|–|250|m|ft|abbr=on}} was only 7% of that found in uncut stands. Other studies determined that seedfall in [[clearcutting|clearcuts]] beyond {{convert|80|m|ft|abbr=on}} from seed trees was about 3% of seedfall in uncut stands where seed trees are close together. Well-stocked stands have resulted from seedfall from sources {{convert|1|–|2|km|mi|abbr=on}} distant, but most Douglas-fir seeds fall within {{convert|100|m|ft|abbr=on}} of their source. Small amounts of seed are dispersed by mice, [[chipmunk]]s, and [[squirrel]]s. Rocky Mountain Douglas-fir seeds are disseminated about twice as far as seeds of [[ponderosa pine]].

==Longevity==
The oldest accurately-dated Rocky Mountain Douglas-fir, 1275 years old, is in [[New Mexico]]. This longevity is apparently uncommon; growing on a relatively barren lava field has protected it from fire, animals, and humans. Growth typically slows dramatically between 90 and 140 years of age.

In the dry-belt forests of central [[British Columbia]], ages can exceed 500 years on sites normal for the region. The oldest accurately-dated growth ring available for the region is 1475; dates in the 1500s and 1600s are more common for remnant patches that have escaped logging, fire, and other disturbances.

==Pathology==
It is affected by the diseases ''[[Phaeolus schweinitzii]]'', ''[[Armillaria]]'', ''[[Phellinus weirii]]'', ''[[Fomes annosus]]'', [[dwarf mistletoe]], [[Dasyscypha canker]] and [[Rhabdocline pseudotsugae|Rhabdocline needle cast]].<ref name=USDA>{{cite book |last1=Patterson |first1=Patricia A. |title=Field Guide to the Forest Plants of Northern Idaho |url=https://www.fs.fed.us/rm/pubs_int/int_gtr180.pdf |date=1985 |publisher=United States Department of Agriculture Forest Service |page=23}}</ref>

==Insects==
It attracts the [[Dendroctonus pseudotsugae|Douglas fir beetle]], [[Choristoneura freemani|western budworm]] and [[tussock moth]].<ref name=USDA/>

==Ecology==
Rocky Mountain Douglas-fir grows on a variety of sites across its wide geographic range. It grows at lower elevations adjacent to and within [[bunchgrass]] communities and is also found in upper-elevation subalpine forests. It tends to be most abundant in low- and middle-elevation forests, where it grows over a wide range of aspects, slopes, landforms, and soils.
[[File:USA 10638 Bryce Canyon Luca Galuzzi 2007.jpg|thumb|left|Rocky Mountain Douglas-fir and ponderosa pine, [[Bryce Canyon National Park]], Utah]]
In spring and winter (in British Columbia, Idaho, and Montana) [[elk]] browse on south- and southwest-facing Rocky Mountain Douglas-fir and ponderosa pine stands, particularly when shrubs and/or grasses are productive. In summer, elk generally are found at higher elevations (outside the Rocky Mountain Douglas-fir and Pacific ponderosa pine zones). During fall, elk use stands of Rocky Mountain [[lodgepole pine]], [[subalpine fir]], [[western larch]], or [[grand fir]] with high canopy cover.

In parts of [[Yellowstone National Park]], elk browsing is so intensive that young Rocky Mountain Douglas-fir are stunted at {{convert|1|–|1.5|m|ft|abbr=on}} in height, with live branches trailing very close to the ground, and branches on the upper two thirds of the tree dead. Low-elevation and south-facing open-structure Rocky Mountain Douglas-fir types are often important winter range for [[white-tailed deer]] and [[mule deer]]. [[Moose]] winter in low-elevation Rocky Mountain Douglas-fir types in areas where willow thickets, the preferred winter habitat, are lacking; in such areas Rocky Mountain Douglas-fir is an important moose food.

[[Chipmunk]]s, [[mouse|mice]], [[vole]]s, and [[shrew]]s eat large quantities of conifer seeds from the forest floor, and clipped cones are a staple and major part of storage of red squirrels. These animals store a large amount of Rocky Mountain Douglas-fir cones or seeds. [[American marten]] commonly den in hollow logs.

Numerous species of [[songbird]]s extract seeds from Douglas-fir cones or forage for seeds on the ground. The most common are the [[Clark's nutcracker]], [[black-capped chickadee]], [[mountain chickadee]], [[boreal chickadee]], [[red-breasted nuthatch]], [[pygmy nuthatch]], [[red crossbill]], [[Two-barred crossbill|white-winged crossbill]], [[dark-eyed junco]], and [[pine siskin]]. Migrating flocks of dark-eyed juncos may consume vast quantities of seeds and freshly germinated seedlings. [[Woodpecker]]s commonly feed in the bark of Rocky Mountain Douglas-fir. [[Blue grouse]] forage on needles and buds in winter; they and other birds rely heavily on Rocky Mountain Douglas-fir communities for cover.

The Douglas-fir is vulnerable to infestation by a [[Eriosomatidae|woolly]] [[aphid]], ''[[Gall Adelgid|Adelges cooleyi]]'' that also infects the [[Engelmann spruce]] to complete its [[Gall Adelgid#Life cycle|lifecycle]].

==Uses==
Rocky Mountain Douglas-fir is a valuable timber tree. The wood is exceptionally strong and is used for structural timber as well as poles, [[plywood]], pulp, dimensional [[lumber]], railroad ties, mine timbers, log cabins, posts and poles, fencing, and firewood. Other uses listed include "machine-stress-rated lumber", glued-laminated (Glulam) beams, pallets, furniture, cabinets, doors, flooring, window frames, and other miscellaneous woodwork and [[Millwork (building material)|millwork]]. Rocky Mountain Douglas-firs are also cut and sold as Christmas trees.

==References==
{{Reflist}}

==External links==
{{Commons|Pseudotsuga_menziesii#Pseudotsuga_menziesii_var._glauca|Rocky Mountain Douglas-fir}}
* [http://plants.usda.gov/java/profile?symbol=PSMEG USDA Plant Profile: ''Pseudotsuga menziesii'' var. ''glauca'' (Rocky Mountain Douglas-fir)]
* [http://www.pinetum.org/cones/PScones.htm Arboretum de Villardebelle - cone photos]
* [https://web.archive.org/web/20050519154710/http://www.conifers.org/pi/ps/glauca.htm Gymnosperm Database: ''Pseudotsuga menziesii'' var. ''glauca'']
* [http://www.fs.fed.us/database/feis/plants/tree/psemeng/index.html US Forest Service Fire Effects Database]
* [http://dougfirflooring.com Site to purchase Douglas Fir Flooring products]
* [https://web.archive.org/web/20130215093525/http://conifersaroundtheworld.com/blog/pseudotsuga_menziesii_var_glauca_oaxacan_douglasfir Conifers Around the World: Pseudotsuga menziesii var. glauca - Oaxacan Douglas-Fir].

{{Taxonbar|from=Q956705}}

[[Category:Douglas fir]]
[[Category:Trees of Northern America]]
[[Category:Flora of the Rocky Mountains]]
[[Category:Flora of the Sierra Madre Occidental]]