Brachypodium distachyon is an attractive model species for biological, physical, genomic and functional studies of the Triticeae. Altitude is an abiotic factor such as latitude/longitude, temperature, humidity and water conditions affecting the plant life. Many researchers have been working on changes in genome size and morphology to highlight the relation of elevational gradients. In this study, genome size and morphological variations was determined in Brachypodium distachyon L. (Poaceae) accessions collected from Turkey. Flow cytometric analysis was performed with 547 individuals representing 89 accessions of B. distachyon from different altitudinal habitats (from 0 to 1219 meters). 2C nuclear DNA content (+/- SD) of B. distachyon was estimated to be 0.736 +/- 0.02 pg. In cytogenetical analysis, all the individuals from every accession were found to have diploid chromosome numbers (2n = 10). To determine the association with genome size (GS), morphologic traits and altitude obtained data were statistically analysed for ANOVA (p<0.005), pearson correlations (p<0.005), principal component analysis, factor analysis, discriminant analysis in Minitab 17 and SPSS 22 versions. The correlation analysis shows that there is no correlation between genome size and altitude. To see the changes of the morphological variations, 5 morphological features such as plant height (13.26 +/- 5.39 cm), plant stature (mostly erect), seed height (7.34 +/- 0.89 mm) and awn length (10.57 +/- 2.24 mm), and 1000-seed weight (4.21 +/- 1.00 mg) was used. We have not found any correlation with changing altitudinal gradients and morphology. However, when we grouped the altitudes from 0 to 600 meters in a collected gradient which represented first group and from 601 to 1219 meters which was the second collected group, we have found a positive correlation between genome size, seed height, awn length, 1000-seed weight and altitude. A negative correlation was only found in plant height along increasing altitudinal levels.