The article presents the results of measuring the DNA content by flow cytometry of S. sanguinolenta and S. borealis species in 50 populations from natural habitats of Russia and Mongolia. Two probable cytotypes for S. sanguinolenta, as well as single samples with multiple changes, and two cytotypes for S. borealis were identified. Samples with the smallest cytotypes are on average 0.32 and 0.38 pg for S. sanguinolenta and 0.36 pg for S. borealis. The studied samples with large cytotypes are distributed mainly in the territories southwest and south of the Baikal Lake and concentrate mostly on the boundaries of the distribution areas of S. sanguinolenta and S. borealis. Samples with large cytotypes contain 1.5 times more DNA (0.49 pg) and 2.2 times more (0.63 pg) for S. sanguinolenta and 1.4 times more (0.49 pg) for S. borealis from the smallest cytotypes. In addition, we measured the DNA content for 7 species of the sanguinolenta-group and 26 other species of the genus Selaginella. Data for 27 species are presented for the first time.