Gypsiferous soils are frequently known for supporting populations of gypsophile plant species. In some cases, such soils may be the only habitat known for such species; such is the case with two southern Nevada, USA species Arctomecon californica and Eriogonum corymbosum. In an effort to better understand habitat requirements for these two rare species in the USA, we examined the surface soil physical, mineralogical and chemical properties of soils across three habitat areas (2 populated solely with the above species and one unpopulated with either) with the objective of determining what site characteristics may influence the tendency for one species to inhabit one area while another does not. In addition, we examined what soil differences may be important for germination and the question of what a gypsophile is. Soils in the area of the study are located in the Mojave Desert in north Las Vegas, NV. Soils are derived from a Pleistocene marsh environment and occur in an aridic moisture regime and thermic to hyperthermic temperature regime. However, prior to sampling, a record rainfall occurred in the region contributing approximately four times the normal rainfall. Ten sites were sampled with 5 holes per site area. Each site constituted several hectares of habitat. Results suggest that gypsum is not a controlling factor for absence or presence of either species and the label of “gypsophile” may be inappropriate. X-ray diffraction analysis confirms no gypsum is presence in the surface soils in any of the habitats, however gypsum is found at depth in most habitats. Sulfur contents in leaves from both species are similar to alfalfa (0.31%); soil sulfate is thirteen times lower in A. californica habitat as compared to E. corymbosum habitat. Both populated habitats have 2-3 times lower available phosphorus as compared to unpopulated areas. A. californica occurs in soils with higher percent surface clast cover and low Na, Ca and Mg availability while E. corymbosum occurs in soils with higher Ca and Mg (9-6 times higher than A. californica respectively) and with a stronger surface crust. A. californica has significantly higher foliar barium, silica and sodium as compared to E. corymbosum and lower aluminum lead, copper, selenium, arsenic, cadmium, chromium and zinc. Based on these observations, we conclude that both species occupy unique niches in the ecosystem studied and may be better described as extremophiles than as gypsophiles. The term gypsophile is likely not appropriate in describing the species.