Knobcone pine
Pinus attenuata
Pinus attenuata is an evergreen coniferous tree of the genus pine (Pinus ), usually with 10 to 12 inches long, usually arranged in groups of three needles and 8 to 15 cm long seed cones. The natural range is in the southwest of the United States in Oregon and California and extends slightly beyond the border to Mexico. The species is hardly used or gardening and is not endangered.
- 5.1 Literature
- 5.2 Notes and references
Description
Appearance
Pinus attenuata grows as evergreen, usually 15 to 20 meters, rarely to 25 m tall tree. In nutrient- poor soils, the type also grow Shrubby The trunk is straight or sometimes curved and reaches a diameter at breast height of 40 to 50 centimeters. The Stammborke is gray-brown to gray, thin, flaky and breaks into small, rectangular plates. The branches are horizontally or upright and form an irregular or rounded, open crown. The shoots are thin and reddish brown. They often have multiple nodes and are covered with short, run-down and lasting pulvini.
Buds and needles
The buds are ovate to ovate - cylindrical and resinous. Terminal buds are 15 to 30 millimeters long and 10 to 15 millimeters thick, pendant buds are shorter. The bud scales are brown, subulate, trockenhäutig, with irregular jagged, translucent edge and a pointed end. The needles grow in threes, rarely in pairs in an initially 10 to 18 millimeters long later shortening to 3 to 6 mm needle sheath and stay two or three years on the tree. They are bright green and sometimes slightly bluish crowded, inelastic, or just hanging, rarely from 8 usually 10 to 12 and sometimes up to 14 centimeters long and 1 to 1.5 millimeters wide. The needle edge is finely serrated, pointed the end. On all sides there are needle stomatal lines on the convex, abaxial side, there are eight to twelve, on the two adaxial sides of three to five.
Cones and seeds
The pollen cones are ovate -oblong to cylindrical, 15-20 mm long and 5-7 mm wide, yellowish to yellow-brown. The seed cones grow individually, in pairs or in whorls of three to five near the ends of branches on short, strong, curved stems. Full-grown cones appear seated, they are bent back, ovate oblong to ovate - narrowed, asymmetrically shaped, 8 to 15 inches long, closed with diameters of 3.5 to 6 centimeters and opened with diameters up to 8 inches. The seed scales are thick, oblong, straight or slightly curved and purple to reddish- brown. The apophysis has a rhombic or pentagonal outline, it is ocher to yellowish brown, slightly shiny and weathered gray. On the bottom of the pin is only slightly increased on the upper side tapered and bent toward the base of the pin reaches a length of 10 millimeters. The umbo is darker than the apophysis rhomboidal, almost flat to pyramidal or hook-shaped, unarmed and reached a size of 5 mm. The seeds are wrong ovoid, flattened, 5-7 mm long and 2.3 to 4.5 millimeters wide and black gray. The seed wing is yellowish to gray- brown, oblong, curved on one side, 12 to 18 mm long and 5-7 mm wide. The seed cones mature after two years, but can at least another 20 years or more are closed, or open only under fire conditions.
Chromosome number
The chromosome number is 2n = pines as with all 24
Top of the tree with seed cones
Seed cones
Distribution, ecology and hazard
The natural range of Pinus attenuata is located in the United States in southwestern Oregon and California and the northwest of the Mexican state of Baja California. The species grows in chaparral and similar vegetation types, but also on very rocky ground. She has extremely resistant spigot and is one of the first trees to colonize the destroyed area after fires. In the northern part of the range in which the trees are a bit higher, it grows along with various species of oak (Quercus spp.). In the United States it grows from 300 to 1200 meters above sea level and rarely reached 1700 meters. In Mexico, they are found mostly at altitudes from 250 to 600 meters or close to the seaside. The distribution area is the hardiness zone 7 associated with mean annual minimum temperatures of -17.7 ° and -12.2 ° C (0 ° to 10 ° Fahrenheit ).
The IUCN Red List is classified Pinus attenuata as not at risk ( " Lower Risk / least concern "). It is noted, however, that a reassessment is necessary.
Systematics and history of research
Pinus attenuata is a species of the genus pine (Pinus ), in which it is assigned to the subgenus Pinus, section and sub-section Trifoliae Austral. It was described in 1892 by John Gill Lemmon first time scientifically. The genus name Pinus was already used by the Romans for several pine species. The specific epithet attenuata comes from the Latin and means " weakened " or " narrows ". It refers to the tapered shape of the pin. Synonyms of species are Pinus californica Hook. & Arn. and Pinus tuberculata Gordon.
It makes no natural hybrids, crossing experiments with Pinus radiata and Pinus muricata, however, were successful. These three types are sometimes grouped together as a group referred to as a closed- cone California pines.
Use
The wood of Pinus attenuata is hardly economically used. Due to the small size and irregular shape of the quality of the wood is low. Growth under dry conditions is slow, except for the resettling of destroyed by fire woods. Polished trunk cross -sections with ingrown pins but sometimes offered as a curiosity for purchase. The species is also horticulturally hardly used and their cultivation is limited to arboretums in areas with a Mediterranean or similar climate.