Abstract: Tamarisk Genetics

The Tamarix invasion in the U.S. is composed of multiple Old World species, some of which are hard to distinguish using morphology. To further complicate matters, there are many putative hybrids across the range of the invasion. We have used genetic markers to identify species composition, origins, relationships, and hybrid events within the invasion. Our analyses have demonstrated that the most common invasive saltcedar genotype is a hybrid between T. ramosissima and T. chinensis, two species with ranges that do not appear to overlap in Asia. Recently, two populations with morphologies intermediate to T. aphylla (athel) and T. ramosissima or T. chinensis were located in Arizona and Nevada. Molecular studies confirmed the hybridization of these species. The athel parental genotypes involved match those of the highly invasive athel of Australia, and the T. ramosissima and T. chinensis parental genotypes are the common U.S. invasives. Our studies also include an analysis of genetic contribution from saltcedars planted in older gardens of Montana to nearby invasions. Garden saltcedars are morphologically very similar to invasive T. ramosissima and T. chinensis, but we have found that cultivated genotypes contributed very little to the invasion. However, we stress that any genetic contribution is detrimental, and so far there is no support for considering any species of the genus a safe ornamental.

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