Astragalus pattersoni, which thrives on the direct intake of selenium from ore bodies , was identified as one of the indicator plants for uranium in case of sandstone type of deposits.
The grass Cynodon dactylon shows preferentially high uranium contents in radioactive areas.
There is a good book titled Geochemical Prospecting for Thorium and Uranium Deposits
By R.W. Boyle please go through it for further references.