Some excerpts from the following links:
Beersheba was to have been the place where Abraham planted a Tamarisk Tree in order to invoke the name of God. To publicly mark his ownership of the well, Abraham gave Abimelekh seven female sheep, and as a testimony to their reconciliation built a well which he symbolically named as Beersheba.
Lines of Tamarisk trees, Tamarisx aphylla, are planted to provide windbreaks, which enhance vegetation growth in the lee of the trees.
Several species were introduced to the S.W. Deserts by the Dept. of Agriculture between 1899 and 1915. The Salt Cedar's pink blossoms on drooping plumes are a favorite of honey bees. But, in addition to increased soil salinity the smaller Salt Cedar, Tamarix pentandra, increases fire frequency within the riparian habitats it dominates. Some important desert springs, critical watering holes for desert wildlife, have been sucked dry by tamarisk. Now the Dept. of Agriculture is using sattelite photos to eradicate and control as much as they can.
In spite of Tamarisks drawbacks, its an important desert tree, providing windbreaks and welcome shade and cover for many animals. It is the source of the Manna of the Bible, which is produced by a small sap sucking insect that turns the toxic sap into a sweet honey like substance that drops to the ground. It is still gathered in the Middle East and sold in the markets.