Picea breweriana

Picea breweriana
Brewer spruce, Ridge above Bear Lake, Siskiyou Mountains, Ca.
Conservation status
Scientific classification
Kingdom: Plantae
Division: Pinophyta
Class: Pinopsida
Order: Pinales
Family: Pinaceae
Genus: Picea
Species: P. breweriana
Binomial name
Picea breweriana
S.Watson
Natural range of Picea breweriana

Picea breweriana (Brewer's weeping spruce or just Weeping spruce) is a species of spruce native to western North America, where it is one of the rarest on the continent, endemic to the Klamath Mountains of southwest Oregon and northwest California. The specific epithet breweriana is in honor of the American botanist William Henry Brewer.[2][3]

DNA analyses[4][5] have shown that Picea breweriana has a basal position in the Picea clade,[4] suggesting that Picea originated in North America.

It grows at moderately high altitudes, from 1000–2700 m.[6][7][8][9][10]

It is a large evergreen coniferous tree growing to 20–40 m 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, 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 mm long and very rough with pulvini 1–2 mm long.

The leaves are borne singly on the pulvini, and are needle-like, 15–35 mm long, flattened in cross-section, glossy dark green above, and with two bands of white stomata below.[6][7] The cones are longer than most other North American spruces, pendulous, cylindrical, 8–15 cm long 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.[6][7]

P. breweriana grows very slowly, typically less than 20 cm (8 in) 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. The harsh ridgetop conditions minimize competition from other much faster-growing trees like Douglas-fir. It is very well adapted to cope with heavy snow and ice loads, with tough branches, and the drooping branchlets shedding snow readily.[6][7][11]

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.[7] This plant has gained the Royal Horticultural Society's Award of Garden Merit.[12]

References

  1. ↑ Nelson, J. & Farjon, A. (2010). "Picea breweriana". IUCN Red List of Threatened Species. Version 3.1. International Union for Conservation of Nature. Retrieved 10 November 2013.
  2. ↑ Ornduff, Robert (2008). "Thomas Jefferson Howell and the First Pacific Northwest Flora" (PDF). Kalmiopsis 15: 32–41. Retrieved 5 March 2012.
  3. ↑ Hyam, R. & Pankhurst, R.J. (1995). Plants and their names : a concise dictionary. Oxford: Oxford University Press. p. 392. ISBN 978-0-19-866189-4.
  4. ↑ 4.0 4.1 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.
  5. ↑ Sigurgeirsson, A. & Szmidt, A.E. 1993. Phylogenetic and biogeographic implications of chloroplast DNA variation in Picea. Nordic Journal of Botany 13(3): 233–246.
  6. ↑ 6.0 6.1 6.2 6.3 Farjon, A. (1990). Pinaceae. Drawings and Descriptions of the Genera. Koeltz Scientific Books ISBN 3-87429-298-3.
  7. ↑ 7.0 7.1 7.2 7.3 7.4 Rushforth, K. (1987). Conifers. Helm ISBN 0-7470-2801-X.
  8. ↑ Conifer Specialist Group (1998). Picea breweriana. 2006. IUCN Red List of Threatened Species. IUCN 2006. www.iucnredlist.org. Retrieved on 5 May 2006.
  9. ↑ Gymnosperm Database: Picea breweriana
  10. ↑ US Forest Service Silvics Manual: Picea breweriana
  11. ↑ Frank Lang's Nature Notes: US Forest Service ecology and the naming
  12. ↑ "RHS Plant Selector - Picea breweriana". Retrieved 26 May 2013.

External links

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