The Salt Plains National Wildlife Refuge in northwest Oklahoma, USA is a moist soil habitat characterized by highly fluctuating salinity (ranging from freshwater to NaCl saturation) and temperature extremes (sometimes exceeding 50 °C). A broad range of halotolerant soil algae occur in this habitat, sometimes within microbial mats or in shallow pools.

A diverse range of Chlorophyceae, Bacillariophyceae and Cyanophyceae have been isolated and provided tentative identification by Dr. Andrea Kirkwood, and representative strains have been deposited in UTEX by Dr. William Henley. These strains have now been cryopreserved and are maintained at UTEX in indefinite storage under liquid nitrogen. An additional strain (UTEX 2795 Picochlorum oklahomensis) is maintained under serial culture.