• Lentibulariaceae contains species with the smallest genome size in tracheophytes, yet data are available only for 8% of its species. This prevents understanding of the history of miniaturization events and their possible reasons. Nothing is known about the variation of genomic DNA base composition. • Genome size and genomic GC content were analyzed with flow cytometry in 119 Lentibulariaceae species. The evolution of both parameters and their correspondence with several ecological traits was tested by sequence-based phylogeny. • Genome size ranged from 1C=73 to 1C=1471 Mbp, with 19 species found to be smaller than Arabidopsis. Miniaturizations have a long history in Utricularia; they also accompany the evolution of Genlisea and two species of Pinguicula. The absence of correlation between genomic parameters and ecological variables suggests that the driving forces of miniaturization are of intrinsic nature. Genome size dynamics associates with extreme variation of GC contents (34.0%–45.1%), being the highest among tracheophyte families. The extremely low GC contents, however, must clearly have evolved with contributions from processes other than sole DNA removal. • The extreme dynamics of Lentibulariaceae genomes provides a unique opportunity for studying genome miniaturization and GC content variation. Hopefully, our study will facilitate the selection of proper model species.