Every year, some 30,000 species around the world go extinct. This is thousands of times the natural, historical rate, and far in excess of the rate at which new species form. Human activities such as habitat destruction and overexploitation are directly responsible for many of these extinctions, but in some cases the link is less direct. Of the 972 plant and animal species listed by the U.S. Endangered Species Act in 1996, approximately 400 were endangered primarily due to invasions by introduced species.
Members of the genus Tamarix , commonly known as saltcedar or tamarisk, comprise the second worst plant invasion in the United States. (The worst is purple loosestrife, Lythrum salicaria .) Tamarix is a deciduous or evergreen shrub or small tree with reddish-brown bark and pink or white flowers. It is insect- and possibly wind-pollinated, and its seeds are wind-dispersed. It grows primarily on riverbanks in arid areas, and is highly resistant to drought and salinity. Under good conditions, a single plant can grow up to 12 feet and produce 250 million seeds in just one year.
Tamarix species are native to a large region stretching from southern Europe and northern Africa across the Middle East and Asia to Japan. In the 1800s, several species were introduced to the U.S. as ornamentals and for erosion control. The genus's hardiness, wide dispersal, and high seed output helped it spread rapidly. It now occupies over one million acres of habitat across 34 states, and is the dominant streamside species throughout the American Southwest.
Copyright ©1988-2015 BioQUEST, Inc. Madison, WI 53744 (608) 363-2012 All Rights Reserved.