Pinus rzedowskii
| Pinus rzedowskii | ||||||||||||
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| Pinus rzedowskii | ||||||||||||
| Madrigal & M. Caball. |
Pinus Rzedowskii is a plant from the genus of pine trees ( Pinus ) within the family of the Pinaceae (Pinaceae). This endemic occurs only in the Coalcoman district in the western part of the Mexican state Michoacán . It is classified as "endangered" inthe IUCN Red List and the population is limited to around 6,000 specimens, of which around 1,000 are fully grown.
description
Appearance
Pinus rzedowskii grows as an evergreen , medium-sized tree and, depending on the location, reaches heights of 15 to 30 meters. The upright and often curved or twisted trunk reaches diameters of 30 to 60 centimeters at chest height . The trunk bark is dark brown and gray when exposed to the weather, 5 to 6 centimeters thick near the base of large trees, rough, scaly and forms flaky plates that are separated by deep cracks. The branches are spread out or ascending and also often twisted. The treetop of young trees is pyramidal, in older trees it is open and irregular. Young shoots are gray, smooth, thin and glabrous.
Buds and needles
The scale leaves are about 5 millimeters long and soon fall off. The vegetative buds are ovate-elongated and not resinous. Terminal buds are 8 to 10 millimeters long with a diameter of 4 to 5 millimeters, lateral buds are almost the same length.
The needles sometimes grow in threes, usually in groups of four or five, in needle sheaths that are initially 7 to 9 millimeters long, which soon curl up and form a rosette at the base of the needle bundle and fall off before the needles. The needles are straight or slightly curved, soft but not drooping, 6 to 10 centimeters long and 0.6 to 0.8 millimeters wide, with an irregularly sawn edge and a pointed to pointed end. The needles are yellowish green to gray-green and slightly glaucous on the adaxial sides . There are stomata only on the two adaxial sides . Four to five resin channels are formed per needle . The needles stay on the tree for two to three years.
Cones and seeds
The pollen cones form on elongated, young shoots and grow spike-like over a length of 5 to 7 centimeters, leaving the base and tip of the shoot free. The cones are small, about 5 millimeters long and 3 millimeters wide, initially purple and later brown.
The seed cones grow individually or in whorls of two to four on 15 to 30 millimeter long stems that fall off with the cones. Fully grown cones are closed ovoid to ovoid-conical, open ovoid, mostly symmetrical and flattened at the base, 10 to 15 centimeters long with a diameter of 6 to 8.5 centimeters. The 50 to 70 or more seed scales are thin, woody, stiff, and elongated. The apophysis is mature ocher-colored to light brown, protruding, cross-keeled, rhombic to pentagonal in outline and less wide than the seed scales. The umbo is dorsal. It is rhombic-pyramidal, keeled across, blunt or reinforced with a small spike . The cones mature within two years.
The brown seeds are usually about 8 (6 to 10) millimeters long and rarely from 4, mostly 5 to 6 millimeters wide. The seed wings are brown with darker stripes, 20 to 30 sometimes to 35 millimeters long and 8 to 13 millimeters wide.
Distribution and ecology
Pinus rzedowskii is endemic to the Coalcoman district in the western part of the Mexican state Michoacán . Pinus rzedowskii only thrives in the Sierra Madre del Sur . A larger population is located near the village of Dos Aguas in a plain locally known as Puerto del Pinabete . There the subsoil consists partly of limestone rock and partly of other materials. The trees reach a height of up to 30 meters. There are two smaller populations consisting of a few tree specimens of different ages about 40 kilometers east on Cerro de Chiqueritas and Cerro Ocotoso . There they grow on steep cones of debris from limestone rocks near the peaks of smaller mountains. These specimens remain small and only reach heights of under 15 meters. In the 1990s, around 10 other locations with only a few specimens were discovered, but this did not significantly expand the distribution area (status 1999).
Pinus rzedowskii grows at altitudes from 2100 to 2400 meters. The annual rainfall is around 1500 millimeters, most of which falls between June and October. The climate is warm and temperate, with minimum temperatures of around -5 ° Celsius in December and maximum temperatures of up to 30 ° Celsius in April. The distribution area is therefore assigned to winter hardiness zone 9 with mean annual minimum temperatures of −6.6 to −1.2 ° Celsius (20 to 30 ° Fahrenheit ). Fires are common in this environment.
The debris cones are surrounded by forests that are home to other pine species such as Pinus pseudostrobus , Pinus herrerae and Pinus oocarpa . However, these species do not penetrate as far as the debris cones, where various oak species ( Quercus ) and shrubs such as Clusia salvinii grow in addition to Pinus rzedowskii . Agaves ( agave ) and herbaceous plants make up the undergrowth.
Hazard and protection
In the Red List of the IUCN is Pinus Rzedowskii as "endangered" (= "Vulnerable") classified. Both the area of distribution (“extent of occurrence”) and the areas with stands (“area of occupancy”) are very small, the total number of tree specimens is estimated at 6,000 to 6,500, the number of fully grown specimens at around 1,000. But there is none Signs of a decline in stocks and enough young specimens. The stocks are also not threatened by deforestation , on the one hand due to the remote distribution area, on the other hand also due to the unfavorable growth habit for exploitation. However, individual populations could very easily be destroyed by fire. In order to reduce this risk, an observation post was set up, which also monitors the increase in stocks.
Systematics
The first description of Pinus Rzedowskii was made in 1969 by Xavier Madrigal Sanchez and Miguel Caballero Deloya in Boletin Tecnico - Instituto Nacional de Investigaciones Forestales . Volume 26, page 1, f. 1-8. The specific epithet rzedowskii is reminiscent of the Polish-born Mexican botanist Jerzy Rzedowsky , who studied the Mexican flora and first described Pinus maximartinezii .
The species Pinus rzedowskii belongs to the subsection Cembroides from the section Parrya in the subgenus Strobus within the genus Pinus . Pinus rzedowskii differs from the other pine species of the sub-section Cembroides in several characteristics . So the seed wings are fully developed, the umbo of the seed cones is sometimes armed with a thorn and the needles are often grouped in groups of five in needle bundles. It was therefore considered to put the species in the Balfouriane subsection or to assign it to its own subsection. As an alternative to this, it has also been proposed to place the long-tapped species of the subsection Cembroides in the subsection Gerardianae , which is otherwise exclusively assigned to Asian species. However, genetic studies confirm the classification in the subsection Cembroides , in which Pinus rzedowskii shows comparatively original characteristics. The closest relatives of this subsection are in the subsection Balfouriane , the similarity with representatives of the subsection Gerardianae can therefore be attributed to convergent development.
use
Nothing is known about the use of Pinus rzedowskii . Pinus rzedowskii is only cultivated in a few botanical gardens and private collections.
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, 755-756 .
- James E. Eckenwalder: Conifers of the World. The Complete Reference . Timber Press, Portland, OR / London 2009, ISBN 978-0-88192-974-4 , pp. 475 .
Individual evidence
- ↑ a b c Pinus rzedowskii in the endangered Red List species the IUCN 2011. Posted by: A. Farjon, 2011. Accessed April 24 of 2019.
- ↑ a b c d e f g Aljos Farjon: A Handbook of the World's Conifers. Volume 2, p. 755
- ↑ a b c d e f James E. Eckenwalder: Conifers of the World , p. 475
- ↑ Christopher J. Earle: Pinus rzedowskii. In: The Gymnosperm Database. www.conifers.org, November 23, 2012, accessed April 24, 2019 .
- ^ Aljos Farjon: A Handbook of the World's Conifers. Volume 2, pp. 755-756
- ↑ a b c d Aljos Farjon: A Handbook of the World's Conifers. Volume 2, p. 756
- ↑ Pinus rzedowskii at Tropicos.org. Missouri Botanical Garden, St. Louis, Retrieved April 24, 2019.
- ^ Aljos Farjon: A Handbook of the World's Conifers. Volume 2, p. 609
Web links
- Vascular Plants of the Americas : Pinus rzedowskii at Tropicos.org. In: 83 . Missouri Botanical Garden, St. Louis