Picea breweriana
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Picea breweriana, known as Brewer's spruce,[1][2] Brewer spruce,[3] Brewer's weeping spruce, or weeping spruce, is a species of spruce native to western North America, where it is one of the rarest on the continent. The specific epithet breweriana is in honor of the American botanist William Henry Brewer.[4][5]
Description
Brewer's spruce is a large evergreen conifer growing to Script error: No such module "convert". tall, exceptionally 54 m, and with a trunk diameter of up to 1.5 m. The bark is thin and scaly, and purple-gray in color. The crown is very distinct, distinguished by level branches with vertically pendulous branchlets up to Script error: No such module "convert".,[6] each branch forming a 'curtain' of foliage. The pendulous foliage only develops when the tree grows to about 1.5–2 m tall; young trees smaller than this (up to about 10–20 years old) are open-crowned with sparse, level branchlets. The shoots are orange-brown, with dense short pubescence about 0.2 millimeters long and very rough with pulvini 1–2 mm long.
The leaves are borne singly on the pulvini, and are needle-like but with a blunt tip,[6] 15–35 mm long, flattened in cross-section, glossy dark green above, and with two bands of white stomata below.[7][8]
The cones are longer than most other North American spruces, pendulous, cylindrical, Script error: No such module "convert". long[6] and 2 cm broad when closed, opening to 3–4 cm broad. They have smoothly rounded, thin, flexible scales 2 cm long. The immature cones are dark purple, maturing red-brown 5–7 months after pollination. The seeds are black, 3–4 mm long, with a slender, 12–18 mm long pale brown wing.[7][8]
Genetics
DNA analyses[9][10] have shown that Picea breweriana has a basal position in the Picea clade,[9] suggesting that Picea originated in North America.
Ecology
Picea breweriana grows very slowly, typically less than Script error: No such module "convert". per year. It occurs mainly on ridgetop sites with very heavy winter snow to provide a steady source of meltwater through the spring, but dry in the summer. It is very well adapted to cope with heavy snow and ice loads, with tough branches, and the drooping branchlets shedding snow readily.[7][8][11]
Because of its slow growth, Brewer's spruce cannot compete with other much faster-growing trees like Douglas-fir. It is also susceptible to wildfire due to its thin bark and pendulous foliage, and therefore is seen to occur in exposed sites with poor, rocky soils, often at high elevation, where competition with other fire-sustaining conifers is reduced. It may also be found sporadically in open montane forests alongside conifer species adapted to similar conditions such as white fir, red fir, or mountain hemlock. The shrub species huckleberry oak and deer oak are other common associates.[12][13]
The species is known to host several species of pathogens and parasites, including the root rot Heterobasidion annosum, the dwarf-mistletoe Arceuthobium campylopodum, and the adelgid Adelges cooleyi.[12]
Distribution
It is endemic to the Klamath Mountains of southwest Oregon and northwest California, and grows at moderately high altitudes, from Script error: No such module "convert". above sea level.[7][8][1][14][15]
Cultivation
Outside its native range, P. breweriana is a highly-valued ornamental tree in gardens, particularly in Great Britain and Scandinavia, where it is appreciated for its dramatically pendulous foliage.[8] This plant has gained the Royal Horticultural Society's Award of Garden Merit.[16][17]
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On a ridge above Bear Lake, Siskiyou Mountains, Ca.
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Foliage of a young tree, ridge above Bear Lake, Ca.
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Picea breweriana in a garden
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The weeping twigs
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Foliage
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Close-up foliage
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Fresh female cones
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Mature male cones & developing female cone
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Mature cone
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Mature Picea breweriana, Royal Botanic Garden, Edinburgh
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References
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- ↑ a b Cite error: Script error: No such module "Namespace detect".Script error: No such module "Namespace detect".
- ↑ Template:BSBI 2007
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- ↑ a b c Script error: No such module "citation/CS1".
- ↑ a b c d Farjon, A. (1990). Pinaceae. Drawings and Descriptions of the Genera. Koeltz Scientific Books Template:ISBN.
- ↑ a b c d e Rushforth, K. (1987). Conifers. Helm Template:ISBN.
- ↑ a b Ran, J.-H., Wei, X.-X. & Wang, X.-Q. 2006. Molecular phylogeny and biogeography of Picea (Pinaceae): Implications for phylogeographical studies using cytoplasmic haplotypes. Mol Phylogenet Evol. 41 (2): 405–19.
- ↑ Sigurgeirsson, A. & Szmidt, A.E. 1993. Phylogenetic and biogeographic implications of chloroplast DNA variation in Picea. Nordic Journal of Botany 13 (3): 233–246.
- ↑ Frank Lang's Nature Notes: US Forest Service ecology and the naming
- ↑ a b Script error: No such module "citation/CS1".
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- ↑ Template:Gymnosperm Database
- ↑ Template:Silvics
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External links
- Template:Jepson Manual
- Catalogue of Life: Picea breweriana Script error: No such module "Unsubst".
- Picea breweriana on Conifer CountryTemplate:Category handler[<span title="Script error: No such module "string".">usurped]Script error: No such module "Check for unknown parameters".
- Template:CalPhotos