Creosote bush
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Creosote bush ( Larrea tridentata ) |
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| ( DC. ) Coville |
The creosote bush ( Larrea tridentata ) in English as a Chaparral or Greasewood , in Spanish as Gobernadora or Hediondilla known, a species of the family of Lignum-vitae ( zygophyllaceae ). This North American species grows in the arid ( arid ) regions of the southwestern United States and Mexico .
etymology
The genus Larrea , which includes the creosote bush, was named after the Spanish clergyman Juan Antonio Pérez Hernández de Larrea (1730-1803), Bishop of Valladolid and patron of the natural sciences. The species name tridentata conferred by Augustin Pyrame de Candolle comes from the Latin tri (three) and dens (tooth) and refers to the scales of petals and stamens (which are difficult to recognize as three-toothed). The name creosote bush comes from the creosote smell that surrounds the entire plant.
description
The creosote bush is an evergreen and thornless shrub that usually reaches 1 to 3, sometimes up to 4 meters in height. Its trunks usually grow upright with numerous branches, but can also drift near the ground. They are initially reddish in color, but turn gray over time. The nodes are darker in color and thickened. The short-stalked, opposite leaves are twofold, there is only a pair of sessile and fused leaflets . The thick, leathery and fleshy, egg-shaped to elliptical or lanceolate leaflets are between 7 and 18 millimeters long and between 4 and 8.5 millimeters wide. They have a whole edge, a rounded to pointed or pointed tip of the leaf, are resinous and smell strongly of creosote. There are small stipules present.
The hermaphroditic and stalked flowers emerge from solitary axillary buds, they are radial symmetry, twisted like a propeller, five-fold and can reach a size of up to 25 millimeters. The five egg-shaped, hairy sepals are free. The five petals are yellow with short nails . There are two circles with five stamens each. The stamens have larger, serrated scales, appendages at the base. The hairy, short-stalked ovary is on top. The 4 to 6 mm long, conical stylus is also still get at the young fruit.
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The short-stemmed, five-part, -samige split fruit is spherical with a diameter of 4.5-5.5 millimeters, it has long, white-silvery hairs.
The number of chromosomes is 2n = 26, 52 or 78.
Taxonomy
Larrea tridentata is the recognized scientific name of the creosote bush. Infrataxa are not available, but there are (misleadingly) several synonym or variety names. The closest related species is Larrea divaricata , which is native to South America ( Argentina ). The genus Larrea also contains the species Larrea ameghinoi , Larrea cuneifolia and Larrea nitida .
distribution
The distribution area of the creosote bush is almost identical to the geological Basin and Range Province up to the north of Nevada . It can be found on the US side in the states of Arizona , California , Nevada , New Mexico and Texas , on the Mexican side in the states of Aguascalientes , Baja California Norte , Baja California Sur , Chihuahua , Coahuila , Durango , Guanajuato , Hidalgo , Nuevo León , Querétaro , San Luis Potosí , Sonora , Tamaulipas and Zacatecas - so it reaches just before Mexico City .
Ecosystems and Associations
The creosote bush community is a distinctive plant community in the Sonoran Desert . But the creosote bush is also the dominant or co-dominant plant species in the Mohave Desert and the Chihuahua Desert . Consequently, it is of great importance in the following ecosystems :
- in the desert shrub ecosystem
- in the Texan savanna ecosystem
- in the shrub steppe ecosystem of the US Southwest and
- in the desert grassland ecosystem
Furthermore, the creosote bush enters into the following plant associations (according to AW Kuchler ):
- with Ambrosia dumosa in the Mohave Desert
- with Ambrosia deltoidea in the Sonoran Desert and
- with Flourensia cernua
Environmental factors and location
The creosote bush is a drought tolerant plant (annual rainfall 100 to 300 millimeters), even with a negative water potential of -50 bar it is still fully functional and can even survive down to -120 bar. In addition, it is exposed to quite high temperature fluctuations (-5 ° C in winter and 47 ° C in summer). It thrives on alluvial cones , on gentle slopes, in valley floors, on sand dunes and in arroyos . Normally it does not rise higher than 1500 meters, but in the San Gabriel Mountains it has been found exceptionally at over 1700 meters (maximum height 2004 meters). The soil substrate is well ventilated, can be of calcareous, sandy or alluvial origin and is often underlain by a solidified caliche horizon made of calcium carbonate.
Propagation and root system
In addition to sexual reproduction through seeds, the shrub can also reproduce vegetatively via budding branches or side roots. The root system of the Kreosotbuschs consists of an up to 80 centimeters long tap root and up to 3 meters long to lateral roots. The latter permeate the surrounding soil so effectively that the plant seems to be able to soak up every drop of water in the vicinity. No other plant can survive nearby. Even your own seedlings lose the fight for water, which makes sexual reproduction difficult. Therefore, the plant solves its propagation problem by forming new stems from the surrounding side roots rather than colonizing the nearby soil with seeds. As the bush spreads, the inner trunks die. As a result, the creosote bush expands into an ever larger ring and continues to grow.
The creosote bush can thus reach an average age of 625 to 1250 years. One such clone ring is estimated to be 11,700 years old, the King Clone in the Lucerne Valley in the Mojave Desert of California .
Folk medicinal use
The Indians of the American Southwest already had various uses for the herb of the creosote bush, they used it e.g. B. as a sunscreen and for blood poisoning and liver disease. In naturopathy, it is found as chaparral in herbal teas and is used in folk medicine, for example, in rheumatism therapy , urethritis, stomach ailments, hemorrhoids , diabetes , high blood pressure and bronchitis, and to strengthen the uterus to improve conception. Efficacy has not been proven for any of the areas of application. Studies have confirmed a strong antioxidant effect, which can be traced back to the content of nordihydroguaiaretic acid (abbreviation NDGA , English Nordihydroguaiaretic acid ) in the leaves of the creosote bush. NDGA has an analgesic , enzyme-inhibiting , anti- diabetic and anti- tumor effect . Because of the anti-tumor effects of NDGA, creosote bush preparations were at times considered to be cancer therapeutics. After the use of creosote bush preparations was linked to liver and kidney damage, the use of NDGA as a food additive ( antioxidant ) was severely restricted in many countries.
Others
The parasitic mosquito Asphondylia aurinila leads to the formation of larger plant galls in the creosote bush .
The creosote bush is very sensitive to fire.
Individual evidence
- ^ Philip A. Munz, David D. Keck: A California flora. Berkeley & Los Angeles: University of California Press, 1959, 1104 pp.
- ^ Thomas H. Kearney, Robert H. Peebles, John Thomas Howell, Elizabeth McClintock: Arizona flora. 2nd Edition, Berkeley, CA: University of California Press, 1960, 1085 pp.
- ↑ Janice C. Beatley: Effects of rainfall and temperature on the distribution and behavior of Larrea tridentata (creosote-bush) in the Mojave Desert of Nevada. In: Ecology. 55, 1974, 245-261.
- ↑ Larrea tridentata at Tropicos.org. In: IPCN Chromosome Reports . Missouri Botanical Garden, St. Louis
- ↑ James C. Hickman: The Jepson manual: Higher plants of California. Berkeley, CA: University of California Press, 1993, 1400 pp.
- ↑ Thomas L. Ackerman, Sam A. Bamberg: Phenological studies in the Mojave Desert at Rock Valley (Nevada Test Site). In: Helmut Lieth: Phenology and seasonality modeling. New York: Springer-Verlag, 1974, 215-226, (Ecological studies; Analysis and synthesis, Volume 8).
- ↑ Tony L. Burgess, David K. Northington: Desert vegetation in the Guadalupe Mountains region. In: Roland R. Wauer , David H. Riskind: Transactions of the symposium on the biological resources of the Chihuahuan Desert region. United States and Mexico, October 17-18, 1974, Alpine, TX, Transactions and Proceedings Series No. 3. Washington, DC, US Department of the Interior, National Park Service, 229-242.
- ↑ David E. Brown: Chihuahuan desertscrub. In: Biotic communities of the American Southwest-United States and Mexico. Desert plants. 4 (1-4), 1982, 169-179.
- ^ Geoffrey A. Levin: How plants survive in the desert. In: Environment Southwest. 1988, Summer: 20-25.
- ↑ Frank C. Vasek: Creosote bush: long-lived clones in the Mojave Desert. In: American Journal of Botany. 67 (2), 1980, 246-255.
- ^ A b Hager's Handbook of Pharmaceutical Practice. Drugs L – Z , Springer, 1998, p. 45 ff, limited preview in the Google book search.
- ↑ E. Teuscher: Biogenic Medicines. 5th edition, Wissenschaftliche Verlagsgesellschaft, 1997, ISBN 3-8047-1482-X , p. 174.
- ↑ C. Schlatter: side effect liver damage In: Pharmazeutische Zeitung. Edition 35/2009.
Web links
- FEIS entry with Fire Effects Information System, US Forest Service.
- Profile on University and Jepson Herbaria Home Page - UC Berkeley.
- Vogel Plant Lexicon .
- Larrea tridentata at SEINet (many pictures).
- Larrea tridentata at Flora of North America.