Pinus maximartinezii
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Young tree in the University of California Botanical Gardens |
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| Pinus maximartinezii | ||||||||||||
| Rzed. |
Pinus Maximartinezii is a plant from the genus of pine trees ( Pinus ) within the family of the Pinaceae (Pinaceae). There are only two localities in two Mexican states. It is classified as "critically endangered" inthe IUCN Red List . The seeds are edible and are harvested and also marketed.
description
Appearance
Pinus maximartinezii grows as an evergreen tree that reaches heights of 5 to 10 and rarely up to 15 meters and a diameter of 40 to 50 centimeters at chest height . The trunk is short and often twisted or curved. The trunk bark is initially reddish brown, later gray, thick near the ground, otherwise thin, mostly smooth and only in old trees it is rough and like a mosaic divided into about 10 centimeters square plates. The branches are long and in the upper part of the tree grow upwards to erect, in the lower part spread out. Twigs bearing cones are pendulous. Young shoots are glabrous or the base of the needle bundle is lightly hairy, initially glaucous or gray-green, later orange-brown to gray.
Buds and needles
The scale sheets are narrow triangular, about 5 millimeters long, tail and bent back. The vegetative buds are resinous, small and ovoid-conical. Terminal buds are 5 to 8 millimeters long.
The needles usually grow in groups of five, very rarely in groups of three or four, in a 7 to 8 millimeter long, light brown needle sheath, the outer scales of which soon fall off. The inner scales bend back and form a rosette at the base of the needle bundle, which, however, falls off before the needles. The needles are straight, soft, 7 to 11 sometimes to 13 inches long and 0.5 to 0.7 millimeters wide. They are entire and pointed, glaucous green, on some trees green, and the adaxial sides often whitish. Only the adaxial sides show stomata lines . Two large resin channels are formed. The needles stay on the tree for two years.
Seedlings and young trees
The relatively large seedlings form 18 to 24 cotyledons . The needles of young trees are curved, flattened, about 8 millimeters long, silver-blue and remain for up to 20 years, i.e. long after normal needles have formed.
Cones and seeds
The pollen cones are yellowish and oval-elongated with a length of 8 to 10 millimeters.
The seed cones grow laterally, individually on thin twigs almost sitting on a short stem. Fully grown cones are usually 17 to 25 (15 to 27) centimeters long and ovoid-trimmed, with open seed scales they have a diameter of 10 to 15 centimeters. The 60 to 110 seed scales are slow to open and often insufficient to release the seeds. They are very thick, woody, stiff, reverse diamond-shaped and about 50 millimeters wide under the apophysis . The shape varies from the base to the tip of the tenon, but is the same around the tenon. Adaxially there are deep indentations which contain the seeds. The apophysis is significantly raised, 35 to 50 millimeters long and 20 to 35 millimeters wide, in the center of the cone rhombic-pyramidal, mostly straight, cross-keeled, matt light brown to reddish brown in color and often resinous. The umbo lies dorsally and is the same color as the apophysis or gray-brown, obtuse-triangular or rhombic-pyramidal and sometimes reinforced with a small spine .
The seeds are elongated or ovate-oblong with a length of 20 to 28 millimeters, a width of sometimes from 8, usually 10 to 12 millimeters and a thickness of 7 to 10 millimeters. The integument is about 2 millimeters thick and very hard. Seed wings are missing when the seeds have detached from the seed scales.
ecology
Fires are common in the area, but it is unclear whether Pinus maximartinezii depends on fire for spread. The pollen is usually released from May to June, the seed cones take 18 to 24 months to ripen, and possibly longer until the seeds, which usually remain in the cones, are also mature. Squirrels (Sciuridae) can bite off the apophysis and get to the seeds. They and probably also birds play a major role in the spread of the seeds, but this has not yet been investigated (as of 2010).
Distribution, locations and endangerment
Pinus maximartinezii only occurs at two localities on Cerro Piñones , a summit of the Sierra de Morones near the city of Juchipila in the south of the state of Zacatecas in Mexico. The two stocks thrive at altitudes of 1800 to 2400 meters. The subsoil consists of sandstone , limestone and metamorphic rock . The soils are shallow and very rocky. The annual rainfall is 700 to 800 millimeters and falls mainly in 4 months in summer. The distribution area can probably be assigned to winter hardiness zone 8 with mean annual minimum temperatures of −12.2 to −6.7 ° Celsius (10 to 20 ° Fahrenheit ).
It is almost the only species of pine in this area, but there are also isolated specimens of Pinus leiophylla var. Chihuahua . In addition, there are often deciduous trees, for example species of the oak genus ( Quercus ) such as Quercus macrophylla , which shed their leaves in the long dry period from September to May.
In December 2010, a second population was discovered at La Muralla in Durango , about 200 kilometers from Juchipila.
In the Red List of the IUCN is Pinus Maximartinezii classified as "critically endangered" as (= "Endangered"). Pinus maximartinezii is only known from stands that together cover about 35 square kilometers ("area of occupancy"), which are located in an area of about 376 square kilometers ("extent of occurrence"). Two separate populations are known, one in Zacatecas with about 2000 to 2500 fully grown tree specimens and another in Durango with about 900 fully grown specimens. It is possible that there are more stocks between these areas. The greatest dangers come from fire and from ongoing erosion caused by grazing livestock. Furthermore, the seeds are used intensively, which could lead to a decline in young seedlings.
Systematics
The first description of Pinus maximartinezii was in 1964 by Jerzy Rzedowski in Ciencia, Revista Hispano-Americana de Ciencias Puras y Aplicadas , volume 23, page 17, f. 1–3, plate 2. The specific epithet maximartinezii honors the Mexican botanist Maximo Martinez (1888–1964), who scientifically examined the conifers of Mexico but did not know Pinus maximartinezii .
The species Pinus maximartinezii belongs to the subsection Cembroides from the section Parrya in the subgenus Strobus within the genus Pinus .
use
As with other species of the Cembroides subsection , the seeds of Pinus maximartinezii are edible and are therefore harvested and marketed locally. Due to the short trunks and the abundant branches, the wood is hardly used. In Mexico it is sometimes used as an ornamental tree , outside of Mexico you can only find Pinus maximartinezii in botanical gardens, for example in the botanical garden of the University of California in Berkeley . Pinus maximartinezii is easy to cultivate and young trees are highly ornamental because of their bluish needles.
swell
literature
- Aljos Farjon: A Handbook of the World's Conifers . tape 2 . Brill, Leiden-Boston 2010, ISBN 978-90-04-17718-5 , pp. 609, 708-709 .
- James E. Eckenwalder: Conifers of the World. The Complete Reference . Timber Press, Portland, OR / London 2009, ISBN 978-0-88192-974-4 , pp. 446-448 .
- Jerzy Rzedowski: Una especie nueva de pino piñonero del estado de Zacatecas (Mexico). In: Ciencias (Mexico) , Volume 23, 1964, pp. 17-20.
Individual evidence
- ↑ a b c Christopher J. Earle: Pinus maximartinezii. In: The Gymnosperm Database. www.conifers.org, 2019, accessed April 26, 2019 (English).
- ↑ a b c d e f g h i j Aljos Farjon: A Handbook of the World's Conifers. Volume 2, p. 708
- ↑ James E. Eckenwalder: Conifers of the World , pp. 446-447
- ↑ a b c James E. Eckenwalder: Conifers of the World , p. 447
- ^ A b Martha González-Elizondo, M. Socorro González-Elizondo, Lizeth Ruacho-González, Moisés Molina-Olvera: Pinus maximartinezii Rzed. (Pinaceae), primer registro para Durango, segunda localidad para la especie . In: Acta Botanica Mexicana . No. 96 , 2011, p. 33-48 ( pdf ).
- ↑ a b Pinus maximartinezii in the IUCN Red List of Threatened Species 2019.1. Listed by: Aljos Farjon, 2011. Retrieved April 26, 2019.
- ↑ Pinus maximartinezii at Tropicos.org. Missouri Botanical Garden, St. Louis, accessed April 26, 2019.
- ^ A b Pinus maximartinezii in the Germplasm Resources Information Network (GRIN), USDA , ARS , National Genetic Resources Program. National Germplasm Resources Laboratory, Beltsville, Maryland. Retrieved April 26, 2019.
- ^ Aljos Farjon: A Handbook of the World's Conifers. Volume 2, p. 609
- ^ Aljos Farjon: A Handbook of the World's Conifers. Volume 2, p. 709
Web links
- Vascular Plants of the Americas : Pinus maximartinezii at Tropicos.org. In: 83 . Missouri Botanical Garden, St. Louis