White spruce, Canada spruce, skunk spruce, cat spruce, single spruce (Peattie 1950, Elias 1987), western white spruce (var. albertiana, Canadian Rocky Mts), Porsild spruce (var. porsildii, Alaska), Black Hills spruce (var. densata, Dakota), épinette blanche (Canadian French) (Taylor 1993).
Syn: Pinus glauca Moench 1785; Abies canadensis Miller; Picea alba (Aiton) Link; P. alba var. albertiana (S. Brown) Beissner; P. albertiana S. Brown; P. canadensis (Miller) Britton, Sterns, & Poggenburg; P. canadensis var. glauca (Moench) Sudworth; P. glauca var. albertiana (S. Brown) Sargent; P. glauca var. densata Bailey; P. glauca var. porsildii Raup; Pinus alba Aiton (Taylor 1993).
Natural hybrids of P. glauca and P. engelmannii are common where the two species are sympatric. "Three varieties have been recognized. P. glauca var. albertiana was described as having unusually prominent leaf bases, cones nearly as broad as long, cone scales acute and broader than long, and an unusually narrow crown. These are common characteristics of hybrids. P. glauca var. porsildii was described as differing from the type variety by having smooth bark with resin blisters, short angular cone scales, an unusually broad crown, and pubescent twigs. These characteristics, also largely intermediate between those of P. glauca and P. engelmannii, may reflect hybridization where the species overlap" (Taylor 1993). P. glauca also freely hybridizes with P. sitchensis to form Lutz or Roche spruce, P. × lutzii, wherever the ranges of the two species overlap, such as along major river corridors across the British Columbia Coast Range and in coastal Alaska. Analysis of this introgression zone indicates that the region was first colonized by P. sitchensis during late Pleistocene deglaciation, with subsequent introgression when P. glauca arrived via dispersal from Alaskan or eastern Canadian refugia (Hamilton and Aitken 2013). Moreover, hybrids between all three species occur in the Skeena River area of British Columbia (Sutton et al. 1994).
Trees to 50 m tall and 100 cm dbh (Farjon 1990); "crown broadly conic to spirelike. Bark gray-brown. Branches slightly drooping; twigs not pendent, rather slender, pinkish brown, glabrous. Buds orange-brown, 3-6 mm, apex rounded. Leaves (0.8)1.5-2(2.5) cm, 4-angled in cross section, rigid, blue-green, bearing stomates on all surfaces, apex sharp-pointed." Seed cones green or violet ripening pale buff, cylindric, soft, "2.5-6(8) cm; scales fan-shaped, broadest near rounded apex, 10-16 × 9-13 mm, flexuous, margin at apex ± entire, apex extending 0.5-3 mm beyond seed-wing impression. 2n=24" (Taylor 1993).
In var. albertiana, the shoots are pubescent and the leaves slightly longer (1.5-2 cm, vs. 0.8-1.3 cm for the type) (Farjon 1990).
Canada: Yukon, North West Territories, British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, Québec, Prince Edward Island, New Brunswick, Nova Scotia, Newfoundland; France: St. Pierre and Miquelon; USA: Alaska, Montana, Wyoming, South Dakota, Minnesota, Wisconsin, Michigan, New York, Vermont, New Hampshire, Maine; at 0-1000 m, "between 5-1900 m (var. albertiana up to 2100 m)." (Farjon 1990). See also Thompson et al. (1999). Hardy to Zone 2 (cold hardiness limit between -45.6°C and -40.0°C) (Bannister and Neuner 2001, variety not specified).
Found in habitats ranging from muskegs, bogs, and river banks to montane slopes (Taylor 1993). It is a dominant tree of interior forests over vast expanses of Canada and Alaska. Where accepted, the varieties are distributed: var. albertiana in the Canadian Rocky Mts., var. porsildii in Alaska, and var. densata in South Dakota.
The top photograph illustrates characteristic habitat partitioning between P. glauca and P. mariana. The two species co-occur over a wide range and have evolved a very complex competitive relationship involving contrasts in tolerance of mesic sites, capacity to reproduce vegetatively, timing of reproductive phenology, rate of seedling and sapling growth, and some other factors. In general, though, P. glauca enjoys a competitive advantage on well-drained mineral soils with deep or no permafrost, such as the alluvial levees along the stream in the photograph, while P. mariana is more tolerant of adverse site conditions including flooding, permafrost and high soil acidity, all of which occur in the muskeg (Elliott-Fisk 1988).
Height 40 m, dbh 101 cm, crown spread 9 m, located in Koochiching County, MN (American Forests 1996). This tree is the type variety. For var. densata, which is restricted to the Black Hills of South Dakota, the tallest seems to be a tree 34.8 m tall along the Needles Highway, and the largest is a tree 32.2 m tall and 94.6 cm dbh near Sylvan Lake; both trees measured in December 2013 (Riddle 2013). For the other varieties, which are hybrids with intrinsically larger species, I have no data.
A tree collected at Kluane Lake in the Yukon Territory had a crossdated age of 668 years. It was collected by B. Luckman, R. van Dorp, D. Youngblut, and M. Masiokas (Luckman 2003, cited by RMTRR 2006).
A crossdated age of 522 years for a specimen from Norton Bay, AK collected by Giddings in 1951 (Brown 1996). I believe this is from a stump; Giddings did a lot of chainsaw sampling.
A search of the Bibliography of Dendrochronology turned up 123 citations, meaning that this species has been used extensively. Studies have examined forest response to autecological factors, tree physiology, fire ecology, spruce budworm outbreaks, climate change, dendrochemistry questions including isotope ratio work, geomorphic change, permafrost dynamics, arctic driftwood, and a variety of miscellaneous topics. The species has proven particularly useful in dendroclimatology because it is one of the more long-lived trees found in northern North America, and sites have been developed across a spatial range covering a hundred degrees of longitude.
The University of Michigan Native American Ethnobotany Database lists 166 examples of use of white spruce by native peoples, here summarized: The sap, gum, needles and inner bark have numerous medicinal uses including panacea, with use by most native peoples in the species' range. The powdered rotten wood was used on babies in lieu of talcum powder, and also to make a yellow dye; the roots were used for cordage and in basketry; the bark was used for roofing, flooring, and canoes (they weren't always birchbark); the wood was used for bark canoe frames, dugout canoes, canoe paddles, and of course structures; and numerous other uses are recorded as well. These included magical uses - for example, the Koyukon thought that the trees would protect those who slept beneath them from malevolent spirits.
Today, it is primarily used for its wood, and is exploited for commercial timber throughout much of its range. See Burns and Honkala (1990) for a review of its significance as a timber species.
It is difficult to pick out a single, or even a few, locations to view such a widely distributed species. However, I will particularly recommend Baxter State Park in Maine because there it grows with Picea mariana and Picea rubens, allowing ready comparison of the species; and it grows at timberline with Picea mariana; and it forms "spruce waves," an extraordinary vegetation formation described (for Abies balsamea, thus "fir waves") by Sprugel (1976) and shown in the bottom two photographs at left.
White spruce is the provincial tree of Manitoba and Black Hills spruce the state tree of South Dakota (Taylor 1993).
Jill A. Hamilton and Sally N. Aitken. 2013. Genetic and morphological structure of a spruce hybrid (Picea sitchensis × P. glauca) zone along a climatic gradient. American Journal of Botany 100(8):1651-1662.
Brian H. Luckman. 2003. Assessment of present, past and future climate variability in the Americas from treeline environments. IAI CRN03 Annual Report 2003.
Douglas G. Sprugel. 1976. Dynamic structure of wave-regenerated Abies balsamea forests in the north-eastern United States. Journal of Ecology 64: 889-911. See also THIS link.
Jess Riddle. 2013.12.14. Needles Highway, SD. www.ents-bbs.org/viewtopic.php?f=123&t=5925, accessed 2014.08.17.
B. C. S. Sutton, S. C. Pritchard, J. R. Gawley, C. H. Newton, and G. K. Kiss. 1994. Analysis of Sitka spruce–interior spruce introgression in British Columbia using cytoplasmic and nuclear DNA probes. Canadian Journal of Forest Research 24(2):278-285.
This page co-edited with Michael P. Frankis, 1998.12.
The FEIS database.
LaRoi, G.H. and J.R. Dugle. 1968. A systematic and genecological study of Picea glauca and P. engelmannii, using paper chromatography of needle extracts. Canadian Journal of Botany 46:649-687.
Last Modified 2014-08-17