Tolerance to high temperature is a valuable trait in crop improvement as well as resilience to other abiotic stresses. High temperatures can be detrimental to germinating seedlings but on the other hand it can also be a dormancy-breaking treatment for nongerminated seeds. We tested the effect of varying high temperature treatments (60^oC, 80^oC and 103^oC) on the seed germination of Physaria fendleri (syn. Lesquerella fendleri) and its relatives P. gordonii, P. argyraea, and Paysonia grandiflora. We also determined the length of time (0.5, 1, 4, 12, 24, 72hr) required before seeds succumb and die after exposure to such temperatures. We observed significant differences in the germination percentages among species and temperature regimes.  Seeds of P. grandiflora were observed to retain viability (3.03%) after 4hr at 103^oC, while seeds of the other species still retained high viabilities (66.67-89.26%) after exposure to 60^oC and 80^oC up to 72hr.  These results demonstrated the tolerance to extreme temperatures in these taxa which may be useful for understanding their resilience in wild habitats, and as well as provide information to plant breeders for further investigation on this trait for future crop improvement activities in lesquerella.