Pinus strobiformis
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| Engelm. |
Pinus strobiformis is a conifer from the genus of the pines ( Pinus ) with needles that grow in groups of five and are usually 7 to 11 centimeters long. The seed cones usually reach a length of 12 to 30 centimeters. The natural range is in the southern United States and Mexico. The species is classified as not endangered inthe IUCN Red List .
description
Appearance
Pinus strobiformis grows as evergreen , 25 to 30 meter high tree . The trunk grows monopodial , straight and upright and reaches diameters of up to 1 meter at chest height . The trunk bark is dark brown and gray, thick, rough and scaly when exposed to the weather and breaks into small, irregularly shaped plates. The branches grow horizontally, curved downwards or ascending. The crown of young trees is conical, older trees have a rounded or irregular crown. Young shoots are lightly downy-haired or hairless, pale reddish brown and have 5 to 10 millimeters long, soon-falling scale leaves .
Buds and needles
The vegetative buds are ovate to ovate-elongated and not or only slightly resinous. Terminal buds are 10 to 15 millimeters long with a diameter of 5 to 8 millimeters, the lateral buds are smaller. The needles grow in groups of five or, very rarely, six in a 20 to 25 millimeter long needle sheath that soon dissolves and falls off at the end of the growing period. The needles are dark green to bluish green, soft, straight or slightly curved near the base, slightly twisted, sometimes from 5 mostly 7 to 11 and rarely up to 12 centimeters long and from 0.6 usually 0.8 to 1.1 and rarely up to 1.2 millimeters thick. The edge of the needle is finely sawn to entire, the end pointed. All sides, or more often only the adaxial sides, show stomata lines . Usually two, rarely up to four resin canals are formed per needle . The needles stay on the tree for three to five years.
Cones and seeds
The pollen cones are yellow, ovate-oblong to short cylindrical and 6 to 10 millimeters long.
The seed cones grow individually or in pairs, sometimes in whorls of three to four on 15 to 25 millimeter long stems. Fully grown cones have different shapes, they are usually cylindrical or broadly cylindrical to ovoid-elongated, 12 to 30 and rarely up to 60 centimeters long with a diameter of 7 to 11 centimeters. The approximately 100 seed scales are thick woody, initially greenish and reddish tinted and light brown when ripe. At the base of the peg they are rolled up or bent back, the others usually have a rolled edge. Each scale has one or two depressions adaxially in which the seeds grow. The apophysis is light yellowish brown to dark ocher colored, more or less wedge-shaped to elongated, thick towards the base and thinning and bent back towards the tip. The surface is smooth or grooved lengthways and very resinous. The umbo lies at the end of the shed, it is broadly triangular and blunt.
The seeds are obovate, 12 to 18 millimeters long and 8 to 11 millimeters wide, reddish brown or brown. The seed wing is usually only rudimentary, very small or in some cones reaches half the length of the seed.
Chromosome number
The number of chromosomes is 2n = 24.
Distribution and ecology
The natural range of Pinus strobiformis is in the United States in Arizona , New Mexico and in Trans-Pecos in western Texas ; in Mexico in the east of the state of Sonora , in Chihuahua , Coahuila , Nuevo León , in the east of Sinaloa , in Durango , Jalisco and locally in Zacatecas and San Luís Potosí .
Pinus strobiformis grows at heights of 1900 to 3500 meters on deep, humus-rich but also stony soils, often on northern slopes and along mountain streams. The climate in the Sierra Madre Occidental is determined by thunderstorm summer rain and also precipitation in winter, at higher altitudes these fall as snow. The distribution area is assigned to winter hardiness zone 7 with mean annual minimum temperatures between −17.7 and −12.3 ° C (0 to 10 ° F ).
The species is sometimes found in small pure stands within pine or pine-oak forests or, more often, mixed with Pinus arizonica , Pinus engelmannii , Pinus leiophylla var. Chihuahuana , Pinus durangensis , Pinus lumholtzii , various types of oak ( Quercus spp.) And strawberry trees ( Arbutus spp.). In more humid areas, Pinus strobiformis grows together with Douglas firs ( Pseudotsuga ) and firs ( Abies ), and at high altitudes with Pinus hartwegii . Pinus strobiformis is the most important host plant for the dwarf mistletoe Arceuthobium blumeri .
Hazard and protection
In the Red List of the IUCN is Pinus strobiformis be deemed not at risk ( "Least Concern"). The range is very extensive and the species is common in the pine forests of the Sierra Madre Occidental but also elsewhere. In some areas there is a decline in stocks due to the use of wood, but the total stock is stable. However, further deforestation that is not geared towards sustainability could endanger the stands. Another danger may provide the Strobenrost ( Cronartium ribicola is), but there is no evidence of infection (as of 2011). In both Mexico and the United States, stocks exist in protected areas.
Systematics and Etymology
Pinus strobiformis is a species from the genus of the pines ( Pinus ), in which it is assigned to the subgenus Strobus , Section Quinquefoliae , Subsection Strobus . It was first described by George Engelmann in 1848 . The species lies both in the morphological characteristics and in the distribution area between Pinus flexilis and Pinus ayacahuite . It is very variable, so the allocation of some stocks is questionable. Hybridization between the species makes clear delimitation more difficult. Therefore, there are also a number of synonyms such as Pinus ayacahuite var. Brachyptera G.R.Shaw , Pinus ayacahuite var. Novogaliciana Carvajal , Pinus ayacahuite subsp. strobiformis (Engelm.) AEMurray , Pinus ayacahuite var. strobiformis (Engelm.) Lemmon , Pinus bonapartea Roezl Pinus ayacahuite var. reflexa (Engelmann) Voss , Pinus flexilis var. reflexa Engelmann and Pinus reflexa (Engelmann) Engelmann .
Hybrids between Pinus strobiformis and Pinus flexilis and Pinus monticola have been proven, but it is not known whether there are also crosses with Pinus ayacahuite .
The generic name Pinus was already used by the Romans for several types of pine. The specific epithet strobiformis refers to the similarity of the species with the Weymouth pine ( Pinus strobus ).
use
The wood of Pinus strobiformis is of high quality and is used as construction timber and for carpentry work. It is also used to make violins. However, due to the small size of the trees and the remoteness of the stands, the species is economically less important than, for example, the Weymouth pine. The resin is used medicinally. The species is rarely cultivated, it is only found outside of the range in arboretums .
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literature
- Aljos Farjon: A Handbook of the World's Conifers . tape 2 . Brill, Leiden-Boston 2010, ISBN 978-90-04-17718-5 , pp. 609, 761-762 .
- James E. Eckenwalder: Conifers of the World. The Complete Reference . Timber Press, Portland, OR / London 2009, ISBN 978-0-88192-974-4 , pp. 478-479 .
- Flora of North America Editorial Committee (Ed.): Flora of North America North of Mexico . Volume 2: Pteridophytes and Gymnosperms . Oxford University Press, New York / Oxford a. a. 1993, ISBN 0-19-508242-7 (English).
- Helmut Genaust: Etymological dictionary of botanical plant names. 3rd, completely revised and expanded edition. Nikol, Hamburg 2005, ISBN 3-937872-16-7 , p. 487 (reprint from 1996).
Individual evidence
- ↑ a b c d e f g h i Aljos Farjon: A Handbook of the World's Conifers. Volume 2, p. 761
- ↑ a b c d e f James E. Eckenwalder: Conifers of the World , p. 478
- ^ Tropicos. [1]
- ↑ a b Pinus strobiformis in the Germplasm Resources Information Network (GRIN), USDA , ARS , National Genetic Resources Program. National Germplasm Resources Laboratory, Beltsville, Maryland.
- ↑ Christopher J. Earle: Pinus strobiformis. In: The Gymnosperm Database. www.conifers.org, November 23, 2012, accessed December 7, 2013 .
- ↑ Pinus strobiformis in the endangered Red List species the IUCN 2013. Posted by: A. Farjon, 2011. Retrieved on December 7, 2013.
- ^ Aljos Farjon: A Handbook of the World's Conifers. Volume 2, p. 609
- ^ Pinus strobiformis. In: The International Plant Name Index. Retrieved December 7, 2013 .
- ↑ a b Pinus strobiformis. In: The Plant List. Retrieved December 7, 2013 .
- ^ Robert Kral: Pinus strobiformis , in Flora of North America. Volume 2
- ↑ To be precise: Etymological dictionary of botanical plant names. P. 487
- ^ A b Aljos Farjon: A Handbook of the World's Conifers. Volume 2, p. 762
- ↑ James E. Eckenwalder: Conifers of the World , p. 479
Web links
- Pinus strobiformis at Tropicos.org. Missouri Botanical Garden, St. Louis, accessed December 7, 2013.