Some species of the carnivorous plant genus Genlisea (Lentibulariaceae) possess ultrasmall nuclear genomes. Fleischmann et al. measure nuclear genome sizes from cultivated plant material for a comprehensive taxon sampling that includes nearly half of all species, and perform chromosome counts for the majority of these taxa. They find a high degree of congruence between genome size distribution and the major phylogenetic lineages. Ultrasmall genomes with 1C-values of less than 100 Mbp are almost exclusively found in a derived lineage of South American species, and they determine the smallest plant genomes known to date in G. tuberosa (1C = approx. 61 Mbp) and some strains of G. aurea (1C = approx. 64 Mbp).