Tamarix
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- Tamarisk redirects here. For other uses of tamarisk, see Tamarisk (disambiguation)
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 Tamarix aphylla in natural habitat in Israel
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The genus Tamarix (tamarisk) comprises about 50-60 species of flowering plants in the family Tamaricaceae, native to drier areas of Eurasia and Africa.
They are deciduous or evergreen shrubs or small trees growing to 1-15 m in height and forming dense thickets, The largest, Tamarix aphylla, is an evergreen tree that can grow to 15 m tall. They usually grow on saline soils, tolerating up to 15,000 ppm soluble salt and can also tolerate alkali conditions. Tamarisks are characterized by slender branches and grey-green foliage. The bark of young branches is smooth and reddish-brown. As the plants age, the bark becomes brownish-purple, ridged and furrowed. The leaves are scale-like, 1-2 mm long, and overlap each other along the stem. They are often encrusted with salt secretions. The pink to white flowers appear in dense masses on 5-10 cm long spikes at branch tips from March to September, though some species (e.g. T. aphylla) tend to flower during the winter.
Tamarix can spread both vegetatively, by adventitious roots or submerged stems, and sexually, by seeds. Each flower can produce thousands of tiny (1 mm diameter) seeds that are contained in a small capsule usually adorned with a tuft of hair that aids in wind dispersal. Seeds can also be dispersed by water. Seedlings require extended periods of soil saturation for establishment. Tamarix species are fire-adapted, and have long tap roots that allow them to intercept deep water tables and exploit natural water resources. They are able to limit competition from other plants by taking up salt from deep ground water, accumulating it in their foliage, and from there depositing it in the surface soil where it builds up concentrations lethal to many other plants.
Tamarix species are used as food plants by the larvae of some Lepidoptera species including Coleophora asthenella which feeds exclusively on T. africana.
- Selected species
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[edit] North American invasive species
Tamarix was introduced to the western United States (where it is often called "salt cedar") as an ornamental shrub in the early 1800s. It establishes in disturbed and undisturbed streams, waterways, bottomlands, banks and drainage washes of natural or artificial waterbodies, moist rangelands and pastures, and other areas where seedlings can be exposed to extended periods of saturated soil for establishment.
It disrupts the structure and stability of North American native plant communities and degrades native wildlife habitat by outcompeting and replacing native plant species, monopolising limited sources of moisture, and increasing the frequency, intensity and effect of fires and floods. Although it provides some shelter, the foliage and flowers provide little food value for native wildlife species that depend on nutrient-rich native plant resources.
It also has caused problem for southwestern municipalities due to its voracious appetite for water. In any given year, Tamarix consumes 163 billion gallons of water from the Colorado River Basin, an amount equivalent to the water allotted to the state of Nevada.
[edit] References
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