Pinus lawsonii
| Pinus lawsonii | ||||||||||||
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| Pinus lawsonii | ||||||||||||
| Roezl ex Gordon |
Pinus lawsonii is an evergreen conifer from the genus of pine ( Pinus ) with mostly 12 to 20 centimeters long, wax-coated needles and 5 to 8 centimeters long seed cones. The natural range is in the southern part of Mexico. The species is not endangered. The wood is used economically, the species is not used as an ornamental plant.
description
Appearance
Pinus lawsonii grows as an evergreen tree 25 to 30 meters high. The single trunk is usually straight or sometimes twisted and reaches a chest height diameter of up to 80 centimeters. The trunk bark is thick, rough and scaly with long, deep, vertical cracks. The outer bark is dark black-brown, the cracks are a little lighter. The branches rise horizontally in the upper part of the crown and form a broad, dome-shaped, irregular, open crown. Young shoots are smooth, glabrous, orange-brown and often tinged with blue.
Buds and needles
The vegetative buds are not resinous and obovate-oblong to cylindrical. Terminal buds are 10 to 15 millimeters long, lateral ones a little shorter. The lower leaves, which are formed as bud scales, are dull brown, awl-shaped-lanceolate , about 10 millimeters long, dry-skinned, with an irregularly jagged and ciliate edge. The needles grow in groups of three to five, rarely in pairs, in a needle sheath that is initially up to 25 millimeters long and later shortens to 10 to 15 millimeters. They are glaucous green, stiff, straight or almost straight, 12 to 20 seldom up to 25 centimeters long and 1.0 to 1.2 seldom up to 1.5 millimeters thick, more or less covered with wax and remain on for two to three years Tree. The edge of the needle is finely sawn, the end pointed and piercing. There are narrow stomata lines on all sides of the needle , on the convex outer surface there are usually nine to twelve from six, on the two inner surfaces four to five. There are rarely more than three to six resin canals formed.
Cones and seeds
The pollen cones are ovate-oblong to cylindrical, 1 to 2 centimeters long with a diameter of 5 to 6 millimeters, initially yellowish green and later light brown. The seed cones grow near the ends of branches, individually or opposite each other, on short, strong, curved stems that fall off with the cone. Ripened cones are closed, narrowly ovate to ovate and tapering to a point, open more or less asymmetrically ovoid, 5 to 8, rarely up to 9 centimeters long with a diameter of 4 to 6, rarely 7 centimeters. The 150 to 250 or more seed scales are more or less rectangular, thickly woody, initially green, mature yellowish brown and bent back when opened. The apophysis is slightly raised, transversely keeled, rhombic in outline with a wavy, notched upper edge, radially striped and light to gray-brown. The umbo is pyramidal and has no clearly developed sting . The seeds are obovate, somewhat flattened, 4 to 5 millimeters long and dark brown. The seed wing is 12 to 16 millimeters long, 5 to 6 millimeters wide, translucent, light brown with a dark tint.
Distribution, ecology and endangerment
The natural range of Pinus lawsonii lies in Mexico in the states Michoacán , México , Morelos , Distrito Federal , Guerrero , Oaxaca and an occurrence in Veracruz .
The species grows in warm temperate to temperate climates in montane forests and woodlands at altitudes of 1300 to 2600 meters. The distribution area is assigned to winter hardiness zone 9 with mean annual minimum temperatures between −6.6 ° and −1.2 ° Celsius (20 to 30 ° Fahrenheit ). The annual rainfall ranges from 600 to 1500 millimeters and the dry season is between November and May. The forests are mostly mixed forests of pine and oak, in which the species can be found, for example, together with Pinus pringlei , Pinus patula , the Montezuma pine ( Pinus montezumae ), Pinus oocarpa , Pinus leiophylla , Pinus herrerae , Pinus teocote and Pinus pseudostrobus . In areas with flat, sandy subsoil, representatives of the juniper ( Juniperus ) can also dominate.
In the Red List of the IUCN is Pinus Lawsonii classified as endangered ( "Lower Risk / least concern"). However, it should be noted that a reassessment is necessary.
Systematics and research history
Pinus lawsonii is a species from the genus of the pines ( Pinus ), in which it is assigned to the subgenus Pinus , Section Trifoliae and Subsection Australes . It was in 1862 by George Gordon in Pinetum scientifically valid for the first time described , its description was based on the foregoing description of Benedict Roezl . The generic name Pinus was already used by the Romans for several types of pine. The specific epithet lawsonii honors the English gardener Charles Lawson (1794–1873), who first validly described the yellow pine ( Pinus ponderosa ). A synonym of the species is Pinus altamiranoi Shaw .
Pinus lawsonii is similar to several other species with which it is found, particularly Pinus herrerae and Pinus pringlei , but neither species has needles that are so clearly coated with wax. Pinus herrerae also has thinner, more flexible needles and the cones of Pinus pringlei stay on the tree for several years.
use
The wood of Pinus lawsonii is used together with the pine trees that grow in the same environment and are usually more common, although the trees are only medium-sized and the trunks are often twisted. In some areas the resin is also extracted. As an ornamental plant, the species only grows under very mild conditions, but no such use is known.
swell
literature
- Aljos Farjon: A Handbook of the World's Conifers . tape 2 . Brill, Leiden-Boston 2010, ISBN 90-04-17718-3 , pp. 699-700 .
- James E. Eckenwalder: Conifers of the World. The Complete Reference . Timber Press, Portland, OR / London 2009, ISBN 978-0-88192-974-4 , pp. 433 .
- 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
- ^ Aljos Farjon: A Handbook of the World's Conifers , Volume 2, pp. 699-700
- ↑ a b c d e f James E. Eckenwalder: Conifers of the World , pp. 442-443
- ↑ Christopher J. Earle: Pinus lawsonii. In: The Gymnosperm Database. www.conifers.org, November 23, 2012, accessed on May 11, 2013 .
- ↑ a b c d e Aljos Farjon: A Handbook of the World's Conifers , Volume 2, p. 700
- ↑ Pinus lawsonii in the endangered Red List species the IUCN 2012. Posted by: Conifer Specialist Group, 1998. Accessed on May 11, 2013.
- ↑ a b Pinus lawsonii. In: The Plant List. Retrieved May 11, 2013 .
- ↑ Exactly: Etymological dictionary of botanical plant names p. 487
- ^ Aljos Farjon: A Handbook of the World's Conifers , Volume 2, p. 699
Web links
- Pinus lawsonii at Tropicos.org. Missouri Botanical Garden, St. Louis, accessed May 11, 2013.