Siskiyou spruce
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Siskiyou spruce ( Picea breweriana ) |
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| Picea breweriana | ||||||||||||
| S. Watson |
The Siskiyou spruce also mane spruce ( Picea breweriana ) is a species from the pine family (Pinaceae). It is native to the Siskiyou Mountains in the southwest USA .
description
The Siskiyou spruce grows as an evergreen tree that can reach heights of growth of up to 40 meters and diameters of up to 1.5 meters at chest height . The conical crown is formed by hanging branches with elongated, also hanging, thin branches. Young trees do not have hanging branches until they are 10 to 20 years old. The trunk bark is gray to brown. The gray-brown bark of the branches is finely hairy.
The gray-brown buds are 5 to 7 millimeters in size and have a rounded tip. The 1.5 to 3 centimeters long, stiff needles have a blunt point. Their cross-section is flattened or broadly triangular with the underside rounded or slightly angular. There are no stomatal ligaments on the dark green top of the needle . On the blue-green underside there are several easily recognizable stomatal ligaments separated from one another by small furrows. The needles are arranged radially on the hanging branches.
The Siskiyou spruce is monoecious ( monoecious ). The dark purple male cones are 1.9 to 3.2 inches long and around 1.3 inches thick. Pollination takes place in early summer. The hanging cones are cylindrical in shape with a length of 6.5 to 15 centimeters. They are initially dark red-purple and turn red to dark brown when they are ripe in September to October. The fan-shaped cone scales are 1.5 to 2 centimeters long and just as wide. Their edges are jagged entirely or somewhat irregularly. The seeds are released from the cones immediately after ripening.
The number of chromosomes is 2n = 24.
Distribution and location
The natural, rugged distribution area of the Siskiyou spruce is in the southwestern United States. It is located between 22 and 145 kilometers from the coast and includes the Siskiyou Mountains in northwestern California and southwestern Oregon . The northern limit of distribution is at Iron Mountain . During the Miocene and Pliocene , the species was also native to Idaho , Nevada , central Oregon, and central California.
The Siskiyou spruce is a tree species of the maritime climate influenced by the Pacific and thrives at altitudes of 530 to 2300 meters. The annual rainfall amounts to more than 2800 mm in the western part of the distribution area and less than 1000 mm in the eastern part, the majority of which falls in autumn and winter as snow or rain. The species grows on serpentine soils but also on rocky or poor soils such as entisoles , which have formed on ultramafic rock . The species is found mainly on ridges and valleys of the subalpine and alpine altitudes, where it grows mainly in forests.
The species forms mixed stands with 15 different types of conifers , with the magnificent fir ( Abies magnifica ) and Douglas fir ( Pseudotsuga menziesii ) being particularly common. Since some of the associated tree species are larger and older than the Siskiyou spruce, it often grows below the canopy. In mixed stands, which are dominated by the Colorado fir ( Abies concolor ), the magnificent fir and the mountain hemlock ( Tsuga mertensiana ), the Siskiyou spruce is occasionally the climax tree . The seedlings of the species often grow together in the undergrowth Arctostaphylos patula , with Quercus sadleriana and with Quercus vaccinifolia . There are also pure stocks, which, however, usually remain small. Due to its susceptibility to forest fires, it is also often found as a single tree in rocky, rather poor locations.
use
Because of its strikingly long, hanging branches, the Siskiyou spruce is well suited as an ornamental tree and is particularly valued in Great Britain. Due to the slow growth, the difficulty of growing this species in culture and the low tolerance to climatic changes, only a few locations are suitable for successful cultivation. The wood is hardly used.
Picea breweriana in a garden in Belgium
Branch with hanging, thin branches
Needles on an end branch
Male cones
Branch with young cones
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Systematics
Picea breweriana is assigned to the subgenus Picea and the section Omorika within the genus of the spruce trees ( Picea ) .
It was first described as Picea breweriana in 1885 by Sereno Watson in Proceedings of the American Academy of Arts and Sciences , Volume 20, page 378. The fossil species Picea sonomensis Axelrod , known from the Oligocene of southwestern Colorado , is regarded as a synonym of Picea breweriana . The specific epithet breweriana honors the professor of agriculture at Yale University , William Henry Brewer , who discovered the species.
Attempts to cross with other spruce species such as the Engelmann spruce ( Picea engelmannii ) and the Sitka spruce ( Picea sitchensis ) were unsuccessful. Molecular studies showed that the Siskiyou spruce is probably not closely related to any other species within the genus of the spruce and that, like the Sitka spruce, it is a basic representative of this genus.
Hazard and protection
The Siskiyou spruce is classified as "low endangered" in the IUCN Red List . It is pointed out, however, that a new review of the hazard is necessary. It is vulnerable to forest fires. Part of the distribution area is located within the Siskiyou National Forest .
swell
- Christopher J. Earle: Picea breweriana. In: The Gymnosperm Database. www.conifers.org, November 28, 2012, accessed April 21, 2013 .
- John W. Thieret: Pinaceae . Picea . In: Flora of North America Editorial Committee (Ed.): Flora of North America North of Mexico . Pteridophytes and Gymnosperms. Volume 2. Oxford University Press, New York a. a. 1993, ISBN 0-19-508242-7 , Picea breweriana (English, Picea breweriana - online - this work is online with the same text).
Individual evidence
- ↑ a b c d e f g h i Christopher J. Earle: Picea breweriana. In: The Gymnosperm Database. www.conifers.org, November 28, 2012, accessed April 21, 2013 .
- ↑ a b c d e Dale Thornburgh: Picea breweriana . In: US Dept. of Agriculture, Forest Service (Ed.): Silvics of North America . Conifers. Volume 1. Washington 1990 (English, Picea breweriana - online - this work is online with the same text).
- ↑ a b Picea breweriana at Tropicos.org. Missouri Botanical Garden, St. Louis, accessed April 21, 2013.
- ↑ Picea breweriana in the endangered Red List species the IUCN 2012. Posted by: Conifer Specialist Group, 1998. Accessed April 21, 2013.
