Thick spruce
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Norway spruce ( Picea pungens ) |
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| Picea pungens | ||||||||||||
| Engelm. |
The blue spruce ( Picea pungens , syn .: Picea parryana Sargent ), colloquially also called blue spruce , is an evergreen species of the spruce genus ( Picea ). The silver spruce is the state tree of the US states Colorado and Utah .
description
Habitus
The spruce is an evergreen tree which , in optimal locations , can grow up to 37 meters in height and up to 1.4 meters in diameter at chest height . The strong and stiff branches are bare and shiny. In young trees they form a regular pyramidal crown . In old trees, the branches are more drooping and form an irregular and open crown.
Foliage
The sturdy needles are square in cross section and 2 to 3 centimeters long. They stand at right angles from the shoot. They have a sharp, pointed apex , which explains the name of spruce. The needle color can vary from tree to tree and varies from yellow-green to blue-green to silver. They often have a wipeable, blue-green wax coating. The specimens planted in Central Europe are mostly breeds with a particularly intense gray to blue color of the needles as a breeding feature. This explains the colloquial name "blue spruce". There are two to four rows of stomata on each side . The taste of the needles is sharp and bitter.
Flowers, cones and seeds
The single-sex ( monoecious ) spruce becomes manable at around 30 years of age . The yellow colored and mostly slightly red tinted male cones are formed in the entire crown area. They are either in groups of three to five at the base or individually at the tips of annual shoots. The light pink to light red colored female cones are only formed in the crown. From them the elongated to cylindrical shaped, seed-bearing cones develop , which are between six and eleven centimeters long. They are initially green in color and have a slightly reddish tint. When they ripen in August to September, they turn straw-colored. The diamond-shaped cone scales are slightly wavy, thin and tough with a straight or uneven edge. The tips of the cone scales are flattened. The seeds are winged. The thousand grain weight of cleaned and deflated seeds is around 4.2 grams.
Chromosome number
The number of chromosomes is 2n = 24.
Root system
The spruce is a shallow root . In the 1st year, seedlings take root to a depth of around 6 centimeters. Despite the shallow root system, the species is hardly susceptible to windthrow .
bark
The gray and somewhat reddish tinted trunk bark is scaly in young trees. In old trees, it is provided with relatively smooth cracks. The bark of young twigs is initially greenish-brown and later changes to an orange-brown to gray-brown color. In some cultivated forms, the young twigs are brown to reddish brown in color.
Wood
The light, light and fine-grained wood of the spruce is similar to the wood of other types of spruce . It has a characteristic odor and is prone to wood rot . The density with a wood moisture content of 0% is around 0.35 g / cm³.
Distribution and location
The silver spruce comes from the Rocky Mountains in the western United States ; their occurrence extends from southern Idaho and Wyoming south to Arizona and New Mexico , where only isolated stocks occur. It forms part of the mountain forest at altitudes between 1,800 and 3,000 meters. The spruce is hardy in Central Europe and Russia and is very often planted in gardens and parks.
The spruce is a type of tree with a cool, mild climate with low temperatures in summer and little rainfall in winter. The annual precipitation is between 460 and 600 mm, of which around 50% falls as rain during the growing season. It is undemanding in terms of location, but prefers nutrient-rich, fresh, sandy to gravelly loams in valleys or on gentle slopes. The pH should be between 6.8 and 7.2. It is very resistant to high air emission values , but can only tolerate a shadow location to a limited extent. It thrives better than other species of spruce in dry locations. It is frost hardy down to a temperature of −40 ° C. The spruce rarely forms pure stands. In lower elevations, mixed stands are formed with different types of willow ( Salix ), with Populus angustifolia , the Douglas fir ( Pseudotsuga menziesii ), the Colorado fir ( Abies concolor ) and the yellow pine ( Pinus ponderosa ). At the upper limit it often forms stands with the Engelmann spruce ( Picea engelmannii ) and the rocky mountain fir ( Abies lasiocarpa ).
use
Due to the strong knots and deforestation, the silver spruce has no significant forestry importance. The silver spruce, especially in cultivated forms with a pronounced blue needle color, is a popular ornamental and Christmas tree . After the Nordmann fir , it is the second most popular Christmas tree in Germany. While the needle durability of freshly felled trees is comparable to that of the Nordmann fir , essential oils from spruce create a Christmas atmosphere. Occasionally it is planted as a windbreak ( hedge ).
Diseases and pests
In its natural range, diseases and pests do not pose a serious threat to the spruce. Annual needles and cones are attacked by cones from the genus Chrysomyxa , which can also cause witch brooms . The fungus Lophodermium piceae attacks the needles and causes severe damage , especially in Denmark . Rhizosphaera kalkhoffii causes needle browning and leads to severe needle loss. This harmful fungus occurs mainly in Christmas tree cultures in the Northeast and the Midwest of the United States. Root and core rot are caused by honey fungus ( Armillaria ) as well as by the pine fire sponge ( Phellinus pini ) and Inonotus tomentosus . A variety of Valsa kunzei causes branch crabs and branch drought.
Galllaus Adelges cooleyi is one of the insect pests that attack the spruce, causing noticeable damage to the shoot tips. The Sitkafichtenlaus ( Elatobium abietinum ) whose suction action leads to a greater or lesser loss of needles, is a major pest in Central Europe occurs. Sometimes all the needles are lost, so that only the new shoot of the tree that takes place in May remains. Repeated infestation can lead to the death of the tree.
The spruce is considered to be resistant to ozone and salt water spray .
Systematics
The thick spruce is similar to the Engelmann spruce ( Picea engelmannii ) in many morphological characteristics and often occurs together with it in lower altitudes. Nevertheless, natural hybrids between the two species rarely occur . The natural variation in needle color is genetically fixed. Picea pungens was first described in 1879 by Georg Engelmann in The Gardeners' Chronicle, new series, volume 11, page 334. Synonyms of Picea pungens Engelm. are: Abies menziesii Engelm. nom. illeg., Picea menziesii Engelm. nom. illeg., Picea commutata Beissn. , Picea parryana (André) coffin. , Pinus armata Voss .
Cultivated forms
At least 38 cultivated forms are described, which differ mainly in the needle color and the crown shape. This includes:
- 'Fat Mac': A dwarf form with only two to three centimeters annual growth.
- 'Glauca': Most of the breeding efforts were aimed at the gray to blue needle color possible. In addition to the shape of 'Glauca', 'Hoopsii', 'Koster' and 'Moerheimii' as well as the columnar shape of 'Iseli Fastigiata' are blue needles.
swell
- David W. Johnson: Picea pungens . In: Peter Schütt, Horst Weisgerber, Hans J. Schuck, Ulla Lang, Bernd Stimm, Andreas Roloff: Lexicon of Conifers. Distribution - Description - Ecology - Use; the great encyclopedia . Nikol, Hamburg 2004, ISBN 3-933203-80-5 , p. 307-314 .
- Christopher J. Earle: Picea pungens. In: The Gymnosperm Database. January 20, 2011, accessed November 8, 2011 .
Individual evidence
- ↑ IPCN Chromosome Reports: Picea pungens Engelm. Tropicos.
- ↑ Pest infestation on Dresden conifers. In: dresden.de. State capital Dresden, May 11, 2015, accessed on February 5, 2017 (press release).
- ↑ a b Rafaël Govaerts (Ed.): Picea. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew . Retrieved April 16, 2019.
- ↑ Mark Brand: Picea pungens Colorado Spruce. In: UConn Plant Database. University of Connecticut, accessed November 26, 2015 .
Web links
- Picea pungens in the endangered Red List species the IUCN 2008. Posted by: Conifer Specialist Group, 1998. Retrieved on December 31 of 2008.
- Thomas Meyer: Data sheet with identification key and photos at Flora-de: Flora von Deutschland (old name of the website: Flowers in Swabia )