Chihuahua white pine
Pinus strobiformis is a coniferous tree from the species of pines ( Pinus ) with five of growing, usually 7 to 11 centimeters long needles. The seed cones reach a length of usually 12 to 30 centimeters. The natural range is south of the United States and in Mexico. The species is classified as not threatened in the IUCN Red List.
- 6.1 Literature
- 6.2 Notes and references
Description
Appearance
Pinus strobiformis grows as evergreen, 25 to 30 meter high tree. The trunk is monopodial, straight and upright, reaching breast height diameter of up to 1 meter. The Stammborke is gray to dark brown and weather influence, thick, rough and scaly and breaks into small, irregularly shaped plates. The branches grow horizontally, bent or ascending by untern. The canopy of young trees is conical, older trees have a rounded or irregularly shaped crown. Young shoots are weakly pubescent or glabrous, pale reddish brown and carry 5 to 10 millimeters long, soon falling shed leaves.
Buds and needles
The vegetative buds are ovate to ovate -oblong, not or only slightly resinous. Terminal buds 10 to 15 mm in length with diameters from 5 to 8 millimeters, the seitständigen buds are smaller. The needles grow to five or six of us in a very rare 20 to 25 millimeters long, soon -resolution and end of the growing period sloping needle sheath. The needles are dark green to bluish green, soft, straight or slightly curved near the base, slightly twisted, sometimes from 5 usually 7 to 11 and rarely up to 12 inches long and from 0.6 usually 0.8 to 1.1 and rarely to 1.2 millimeters thick. The needle edge is finely toothed to entire, the pointed end. All pages or more often only the adaxial sides show stomatal lines. The needle is usually two, rarely formed by four resin canals. The needles remain three to five years on the tree.
Cones and seeds
The pollen cones are yellow, ovate - oblong to short cylindrical, 6-10 mm long.
The seed cones grow singly or in pairs, sometimes in whorls of three to four to 15 to 25 millimeters long stems. Full-grown cones have different forms, they are usually open cylindrical or broadly cylindrical to ovate -oblong, 12 to 30, and rarely up to 60 inches long with diameters 7-11 centimeters. The approximately 100 seed scales are thick woody, initially greenish tint and reddish and light brown at maturity. At the spigot base they are curled or bent back, the others usually have a rolled edge. Each scale has adaxial one or two wells in which the seeds grow. The apophysis is light yellowish brown to dark ocher color, more or less wedge-shaped to oblong, thick towards the base and becoming less and bent back to the top. The surface is smooth or longitudinally grooved and very resinous. The umbo is situated at the shed end, he is broadly triangular and blunt.
The seeds are obovate, 12-18 mm long and 8-11 mm wide, reddish brown or brown. The seed wing is usually formed only rudimentary, very small or achieved in some stud -half the length of the seed.
Distribution and ecology
The natural range of Pinus strobiformis located in the United States in Arizona, New Mexico and Trans - Pecos in the west of Texas; in Mexico in the east of the state of Sonora, Chihuahua, Coahuila, Nuevo León, to the east of Sinaloa, Durango, Jalisco and Zacatecas and San Luis locally in Potosí.
Pinus strobiformis grows at altitudes 1900-3500 meters on deep, humus-rich but also stony soils common in northern slopes and along mountain streams. The climate in the Sierra Madre Occidental is determined by thunderstorm -like summer rain and winter precipitation, at greater heights this fall as snow. The distribution area is the hardiness zone 7 attributed with mean annual minimum temperatures between -17.7 to -12.3 ° C (0 ° to 10 ° Fahrenheit ).
One finds the way sometimes 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 species of oak (Quercus spp.) And strawberry trees ( Arbutus spp.). In wetter areas Pinus strobiformis grows along with Douglas fir (Pseudotsuga) and fir (Abies ), and hartwegii at high altitudes with Pinus. Pinus strobiformis is the main host plant of the dwarf mistletoe Arceuthobium blumeri.
Threats and conservation
The IUCN Red List is led Pinus strobiformis as not at risk ( "Least Concern" ). The distribution area is very extensive and the species is in the pine forests of the Sierra Madre Occidental and elsewhere often. In some areas it is due to the use of wood to declines in stocks, but the overall population is stable. However, a risk to the stock could come from further, not focused on sustainability clearings. Another danger may represents the Strobenrost ( Cronartium ribicola ), but there is no evidence of infection (as of 2011 ). Both in Mexico and in the United States, there are also resources in protected areas.
Systematics and etymology
Pinus strobiformis is a species in the genus of pine (Pinus ), in which it is assigned to the subgenus strobus, Quinquefoliae section, sub-section strobus. It was first described in 1848 by George Engelmann. The type is in both the morphological features as well as in the distribution area between Pinus flexilis and Pinus ayacahuite. It is very variable, so the assignment of some stocks is questionable. Hybridization between species complicates additionally the clear demarcation. Therefore, there are also a number of synonyms such as Pinus ayacahuite var brachyptera GRShaw, 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 and Pinus flexilis var reflexa Engelmann and Pinus reflexa ( Engelmann ) Engelmann.
Hybrids between Pinus and Pinus flexilis and Pinus strobiformis monticola are occupied, whether there are crosses with Pinus ayacahuite is not known.
The genus name Pinus was already used by the Romans for several pine species. The specific epithet refers to strobiformis the similarity of style with the Weymouth pine (Pinus strobus ).
Use
The wood of Pinus strobiformis is high quality and is used as timber and joinery. It is also used to produce violins. However, due to the small size of the trees and the remoteness of the stocks, the species is economically less important than, say, the Weymouth pine. The resin is used medically. The species is rarely cultivated, they are found outside of the range only in arboretums.