Diethyl sulphate (DES) was used to induce genetic variability in Gaillardia pulchella plant to improving morphological characters. Besides, changes in the genomic DNA between mutant plants and the control were determined. The seeds were soaked in four different concentrations of DES (1000, 2000, 3000, and 4000 ppm) for 8 h. The results indicated that untreated plants gave the highest values of seed germination in M₁ and M₂, whilst 4000 ppm recorded the lowest value. The concentrations of 1000 and 2000 ppm increased the plant height, giving values of (125.47 and 118.96 cm in M₁) and (120.10 and 121.45 cm in M₂) compared to (110.07 cm in M₁ and 114.12 cm in M₂) for the control. The highest numbers of branches were (15.23 and 16.87 in M₁) and (17.10 and 18.17 in M₂) compared to (12.27 in M₁ and 14.20 in M₂) for the control. 3000 and 4000 ppm delayed flowering compared to the control. In contrast, 2000 ppm induced early flowering and increased the flowers number, compared to the control. Many mutants in leaves and inflorescences morphology were observed; the largest number of these mutants was obtained from 4000 ppm. SRAP mars were used to confirm the existence of genetic variability at the genomic DNA level among populations treated with DES and control, depending on the concentration of DES. Therefore, SRAP markers are considered an important tool in detecting the mutagenic effects of DES. Also, it will help to discriminate between populations showing mutations in morphological and floral characteristics.