The Earth is composed of multiple chemical compositions of soil, some of which are more hospitable to plant life than others. The less hospitable of these soils can prevent the growth of most plant species, although some species have evolved to withstand and even thrive in such conditions. This evolutionary response to difficult soil conditions can be seen in plants that strictly grow in gypsum. Gypsum (CaSO4·2H2O) is typically a very harsh environment for plants to grow in, due to its characteristic hard crust and lack of many essential nutrients necessary for the growth of most plants. Nevertheless, a subset of plants known as gypsophiles are only known from gypsum soils. Within North America, gypsum is most commonly found in island-like outcrops within the Chihuahuan Desert of northern Mexico and the southwestern US. This non-continuous distribution of gypsum soil may promote speciation in gypsophile plant groups, as gene flow is generally limited among gypsum outcrops. Haploësthes (Asteraceae) is a small genus of five species and three varieties, all of which grow only in gypsum soils in the Chihuahuan Desert region. The taxonomy of Haploësthes has mainly been based on the morphology and chromosome counts, and species boundaries are not entirely clear. To define the species boundaries and build a clearer picture of the evolutionary relationships present within Haploësthes, we are sequencing 300 genes from multiple individuals from multiple populations of all taxa in Haploësthes. We will also be able to investigate patterns of possible gene flow among and within species in the genus.