Arizona cypress
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Arizona cypress ( Cupressus arizonica ) |
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The Arizona cypress ( Cupressus arizonica ) is a plant from the genus of the cypress ( Cupressus ) within the family of the cypress family (Cupressaceae).
description
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Appearance
The Arizona cypress ( Cupressus arizonica ) grows as a medium-sized, straight-stemmed, evergreen tree . It reaches heights of growth of 10 to 20 meters with a breast height diameter (BHD) of up to 80 centimeters. The ovoid-conical crown is light gray to dark green. The branches protrude horizontally from the trunk. The stiff and dense twigs are distributed evenly, either alternately or opposite, on the branches.
bark
The bark of Cupressus arizonica varies in structure and color depending on its age. With a BHD of up to 15 centimeters and with thicker branches, the bark is colored cherry red. It is smooth and comes off the trunk in thin, rolled up, non-fibrous sheets. With a BHD of 15 to 30 centimeters, the bark is dark brown in color. It is thin and consists of irregularly square or elongated plates that do not flake. With a BHD of more than 30 centimeters, the bark is longitudinally cracked and dark brown to gray in color. It is fibrous and thick and does not flake off.
Wood
The yellowish heartwood differs in color from the red-brown sapwood . The wood of Cupressus arizonica is very light, finely textured and has a straight grain. Because of the poor quality, it is of little economic importance. The bulk density is 0.48 g / cm³. The wood has an irregular annual ring structure that is closely related to the soil moisture. There are also double annual rings. Often, frost rings appear on seedlings and branches.
Foliage
The scale-like leaves are only 2 to 5 millimeters long. They are keeled or furrowed underneath. Cupressus arizonica has blue-green colored leaves and a sharply pointed upper end. The expression of the resin glands is very variable. The separated resin has a whitish to dark color.
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Flowers, cones and seeds
In terms of flower morphology, there are hardly any differences between the varieties. Cupressus arizonica are all single sexed ( monoecious ) and become male at the age of 4 to 5 years. They only develop female cones for the first 1 to 2 years. The flowering period extends from January to February. The male cones have a length of only 3 to 5 millimeters and a diameter of 2 millimeters; they get narrower towards the tip. There are several at the ends of short shoots that are no more than 8 to 10 millimeters long. They consist of 12 to 20 stamens , each with four to six pollen sacs . The female cone-flowers are terminally on the branches and are thicker than the male cone-flowers. They are enclosed by leaflets that overlap like roof tiles. Before pollination, they are about 3 millimeters long and just as wide. The scales have ciliate edges. The cones are spherical to elongated, 20 to 25 mm long and reach a diameter of 20 to 22 millimeters. They have six or eight (rarely four or ten) seed scales. First green, the cones turn gray or gray-brown as they ripen 18 to 24 months after pollination. They release the seeds in the autumn of the 2nd year after pollination. One cone contains around 90 to 120 seeds.
The thin and winged, dark brown seeds are about 4 to 5 millimeters long. The seed is smooth, except for a few warty bumps, and is oval to spherical. The wings are about 1 millimeter wide. The thousand grain weight is between 8 and 9 grams.
Chromosome number
The number of chromosomes is 2n = 22.
Distribution and location
The Arizona cypress is found in the US states of Arizona , New Mexico and California and in the Mexican states of Coahuila , Chihuahua , Durango , Tamaulipas , Zacatecas and northern Baja California . They grow at altitudes of 1000 to 2900 meters.
The Arizona cypress thrives in the lower layers of semi-arid mountain ranges with annual rainfall between 250 and 500 mm. The air temperature fluctuates between −17 ° C and over 30 ° C. It occurs on coarse and sediment-rich granite and weathered limestone soils with pH values of 5.5 to 8.3. Sometimes also on clay and sandstone . It is a species of light tree. It is considered to be sensitive to fire. It is considered insensitive to winter cold and late frosts and drought-resistant .
In nature, Cupressus arizonica often occurs in small, dispersed populations rather than in large forests. It often forms mixed forests with the alligator juniper ( Juniperus deppeana ), with the Arizona plane tree ( Platanus wrightii ), with Juglans major , with Pinus edulis and with various types of oak ( Qercus spec.).
use
Due to its poor wood quality, Cupressus arizonica is not used economically other than as firewood .
Cupressus arizonica is often planted in the temperate latitudes as an ornamental plant and as a protection against erosion . It is not suitable for windbreaks because the trunks shed the lower branches from a certain height.
Diseases and pests
The Arizona cypress is sensitive to infestation with the Cinara cupressi louse species . An infestation can be recognized by a reddish discolored crown and numerous drought. The var. Arizonica is susceptible to cypress cancer, which is caused by the pathogen Seiridium cardinale , while the var glabra is resistant. The fungus Phomopsis juniperovora colonizes the tissue of branches and causes branch cancer . The fungus Cercospora sequoidae attacks young plants and leads to browning and shedding of leaves and young twigs in late summer. Kabatina thujae is a type of fungus that causes shoots to die off, which can lead to the death of smaller trees. The species is resistant to drought, cold and late frosts.
Systematics and risk
The classification as subtaxon or species is controversial. Cupressus arizonica is on the IUCN Red List of Endangered Species .
swell
- Paolo Raddi, Alberto Panconesi: Cupressus arizonica . In: Peter Schütt, Horst Weisgerber, Hans J. Schuck, Ulla Lang, Bernd Stimm, Andreas Roloff: Lexicon of Conifers. Distribution - Description - Ecology - Use; the great encyclopedia . Nikol, Hamburg 2004, ISBN 3-933203-80-5 , p. 151-160 .
- Christopher J. Earle: Cupressus arizonica. In: The Gymnosperm Database. 2019, accessed on March 27, 2019 .
Individual evidence
- ^ Cupressus arizonica at Tropicos.org. In: IPCN Chromosome Reports . Missouri Botanical Garden, St. Louis
- ↑ Cupressus arizonica in the endangered Red List species the IUCN 2006. Posted by: Conifer Specialist Group, 1998. Retrieved on 12 May, 2006.
