Pinus durangensis
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Pinus durangensis is a plant from the genus of pine trees ( Pinus ) within the family of the Pinaceae (Pinaceae). The natural range is in Mexico, mainly in the Sierra Madre Occidental . It is classified as "not endangered" inthe IUCN Red List . It forms large, straight trunks and is an important supplier of wood.
description
Appearance
Pinus durangensis grows as an evergreen tree that reaches heights of 35 to 40 meters. The trunk is usually upright and straight and reaches a diameter of 80 to 100 centimeters at chest height . The trunk bark is rough, scaly and breaks into large, irregular, elongated, gray-brown, weathering gray plates, which are separated by flat, vertical, dark brown cracks. The branches are long and thin and are mostly horizontal. The lower branches are bent downwards, the lowest ones drooping. The crown is rounded. Young shoots are hairless, orange-brown or reddish brown and mostly glaucous . They are initially rough due to fallen bracts and become smooth by the third year.
Buds and needles
The lower leaves are dark brown, up to 15 millimeters long, at the base 3 to 4 millimeters wide, awl-shaped , dry-skinned, bent back early and provided with an irregularly jagged and ciliate edge and a tailed tip. The vegetative buds are egg-shaped and not resinous. Terminal buds are 15 to 20, rarely up to 25 millimeters long with diameters of 10 to 15 millimeters. The lateral buds are smaller. The needles usually grow in groups of five or six, sometimes four or seven, rarely eight in a 20 to 30 millimeter long needle sheath that is shortened to 10 to 15 millimeters. The needles are yellowish green to waxy bluish ( glauk ) green, stiff, straight or slightly curved, 14 to 24 centimeters long and 0.7 to 1.1 millimeters thick. The edge of the needle is finely sawn, the end pointed to piercing-pointed. There are clear stomata lines on all sides of the needle . Usually three, less often only one or two or up to five resin canals are formed. The needles stay on the tree for two to three years.
Cones and seeds
The pollen pins are brown to maturity yellowish, ovate to oblong to cylindrical and 15 to 30 millimeters long. The seed cones grow singly, in pairs or whorls of three or four near the ends of the branches on short, thick, permanent, or sometimes with the cone sloping stems. Ripe, open cones are ovate to broadly ovate, slightly flattened or bluntly conical in shape at the base, slightly curved, usually 5 to 9, rarely up to 11 centimeters long with a diameter of 4 to 6, rarely up to 7 centimeters. The seldom from 60, mostly 75 to 120 seed scales are thick woody, broadly elongated, straight or bent back near the cone base. Except for the scales near the base, they fall off early when the seeds are released. The apophysis is usually elevated, with scales near the base of the cones flat, rhombic to pentagonal in outline, clearly keeled across, ocher to light brown or light reddish brown. The umbo is dorsal. It is raised, slightly bent back, keeled transversely and reinforced with a mostly permanent, rarely also soon falling sting .
The seeds are at a length of 5 to 6 millimeters and a diameter of 4 to 4.5 Millimeternt wrong ovoid, slightly flattened, light brown to gray and with small dark spots provided. The seed wing is crooked, 14 to 20 millimeters long, 6 to 9 millimeters wide, light gray-brown, translucent with a slight black tint.
ecology
Several species of dwarf mistletoe ( Arceuthobium ) grow parasitically on Pinus durangensis .
Occurrence and endangerment
The natural range of Pinus durangensis is in Mexico in the south of the state Chihuahua , in Durango , in the east of Sonora , in Jalisco , Zacatecas and in the north of Michoacán .
The main distribution center of Pinus durangensis is in the Sierra Madre Occidental . You can find them at altitudes of mostly 1600 to 2800 meters, less often from 1400 meters and maybe even up to 3000 meters. The climate is warm-temperate, but there are also cold spells in higher altitudes in the short winter. The distribution area is assigned to winter hardiness zone 8 with mean annual minimum temperatures between −12.2 and −6.7 ° Celsius (10 to 20 ° Fahrenheit ). The annual rainfall in the distribution area is between 700 and 2800 millimeters, with the largest part falling in summer. The species can grow on flat, rocky subsoil, but it is more often found on deep soils, where it successfully asserts itself against other pine species. The soils are mostly of volcanic origin. In the Sierra Madre it forms an important part of the pine forests typical there and can occur in pure stands or together with, for example, Pinus arizonica , Pinus leiophylla and Pinus engelmannii . Other Pinus species it grows with are Pinus montezumae and Pinus teocote , in the south of the Pinus ayacahuite distribution area . They are also often found in mixed forests of pine and oak. In the highest altitudes it grows together with firs ( Abies ) and with the Mexican cypress ( Cupressus lusitanica ), in the lowest altitudes with the alligator juniper ( Juniperus deppeana ) and Pinus oocarpa .
In the Red List of the IUCN is Pinus durangensis "not at risk" (= "Lower Risk / least concern") classified. It should be noted, however, that a reassessment is pending. Pinus durangensis makes large, straight trunks and the wood is used extensively, especially in the state of Durango. Extensive pure stocks are now rare there. However, mature and old trees are still common in mixed forests and in remote areas. Protection may still be necessary to avoid overuse.
Systematics and research history
The first description of Pinus durangensis was made in 1942 by Maximino Martínez in the Anales del Instituto de la Universidad Nacional de Biológia de México , Volume 13, page 23 f. 1-4. The type specimen comes from El Salto in the state of Durango. The specific epithet durangensis refers to the location of the type specimen in the state of Durango. Synonyms for Pinus durangensis Martínez are: Pinus douglasiana var. Martinezii (E.Larsen) Silba , Pinus martinezii E.Larsen .
The species Pinus durangensis belongs to the sub-section Ponderosae from the section Trifoliae in the sub-genus Pinus within the genus Pinus .
Pinus durangensis usually has five to six and up to eight needles per needle bundle, the highest number of needles of all pines. The number of needles depends partly on the latitude; pines growing further north usually show a lower number. Even further north is the distribution area of Pinus arizonica with mostly four to five needles. The relationship between these two species is not yet fully understood and needs to be investigated more closely. There could also be a closer relationship to Pinus ponderosa . Sometimes the sub-section Australes is considered, but the species is mostly assigned to the sub-section Ponderosae due to the structure of the bark, the needles and the seed cones as well as genetic studies.
use
Pinus durangensis is an important supplier of wood. It forms large and straight stems and is or was widespread and numerous. However, the deforestation outstrips the growth and management in plantations has not started.
The wood is used as lumber for roof trusses, general carpentry, furniture and flooring, and plywood.
swell
literature
- James E. Eckenwalder: Conifers of the World. The Complete Reference . Timber Press, Portland, OR / London 2009, ISBN 978-0-88192-974-4 , pp. 427 .
- Aljos Farjon: A Handbook of the World's Conifers . tape 2 . Brill, Leiden / Boston 2010, ISBN 978-90-04-17718-5 , pp. 667-668 .
- 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 Aljos Farjon: A Handbook of the World's Conifers. Volume 2, 2010, p. 667.
- ↑ a b c d e f James E. Eckenwalder: Conifers of the World. 2009, p. 428.
- ↑ a b Christopher J. Earle: Pinus durangensis. In: The Gymnosperm Database. www.conifers.org, November 28, 2012, accessed June 22, 2013 (English).
- ↑ Pinus durangensis in the Germplasm Resources Information Network (GRIN), USDA , ARS , National Genetic Resources Program. National Germplasm Resources Laboratory, Beltsville, Maryland. Retrieved June 22, 2013.
- ^ Aljos Farjon: A Handbook of the World's Conifers. Volume 2, 2010, pp. 667-668.
- ↑ Pinus durangensis in the endangered Red List species the IUCN 2012. Posted by: Conifer Specialist Group, 1998. Accessed June 22, 2013.
- ↑ a b c Aljos Farjon: A Handbook of the World's Conifers. Volume 2, 2010, p. 668.
- ↑ a b c Pinus durangensis at Tropicos.org. Missouri Botanical Garden, St. Louis, accessed April 19, 2019.
Web links
- Vascular Plants of the Americas : Pinus durangensis at Tropicos.org. In: 83 . Missouri Botanical Garden, St. Louis