The genus tamarix (tamarisk, salt cedar) is composed of about 50–60 species of flowering plants in the family tamaricaceae, native to drier areas of eurasia and africa. the generic name originated in latin and may refer to the tamaris river in hispania tarraconensis (spain).
Tamarix species are commonly believed to disrupt the structure and stability of North American native plant communities and degrade native wildlife habitat, by outcompeting and replacing native plant species, salinizing soils, monopolizing limited sources of moisture, and increasing the frequency, intensity, and effect of fires and floods. While individual plants may not consume larger quantities of water than native species, large, dense stands of tamarisk do consume more water than equivalent stands of native cottonwoods. An active and ongoing debate exists as to when the tamarisk can out-compete native plants, and if it is actively displacing native plants or it just taking advantage of disturbance by removal of natives by humans and changes in flood regimens. Research on competition between tamarisk seedlings and co-occurring native trees has found that the seedlings are not competitive over a range of environments, but stands of mature trees effectively prevent native species' establishment in the understory, due to low light, elevated salinity, and possibly changes to the soil biota. Box elder (Acer negundo, a native riparian tree) seedlings survive and grow under higher-shade conditions than Tamarix seedlings, and mature Tamarix specimens die after 1–2 years of 98% shade, indicating a pathway for successional replacement of Tamarix by box elder. Anthropogenic activities that preferentially favor tamarisk (such as changes to flooding regimens) are associated with infestation. To date, Tamarix has taken over large sections of riparian ecosystems in the western United States that were once home to native cottonwoods and willows, and are projected by some to spread well beyond the current range.