to growth in both the longitudinal and transverse directions, when UgPHV1 / PHAVOLUTA (PHV) is restricted. Expression of UgPHV1 inhibits trap development and leads to the formation of leaflets. The same model can be used to describe shape development of other leaf shapes, including the pitcher-shaped Sarracenia trap, in terms of the spatial regulation of gene expression. Increased respiration rates caused by mutated COXI may have caused two additional traits in the Utricularia–Genlisea clade: i) greatly increased rates of nucleotide substitution and ii) a dynamic decrease of genome size, including Utricularia species with some of the smallest haploid angiosperm genomes known. A recent study conducted three cDNA libraries from different organs of U. gibba (~80Mb) as part of a large scale Utricularia nuclear genome sequencing project. They recorded increased nucleotide substitution rates in chloroplast, mitochondrial, and cellular genomes. They also recorded increased levels of DNA repair-associated proteins and reactive oxygen species (ROS)-detox. ROS is a product of cellular metabolism that can potentially cause cellular damage when accumulated in high amounts. They determined the expression of DNA repair and ROS detox was ubiquitous rather than trap-specific. Due to this ubiquitous expression, relative ROS detoxification is expected to be lower in trap structures due to the high respiratory rate caused by trap activations, eventually leading to higher toxic effects and mutagenesis. Mutagenic action of enhanced ROS production may explain both high rates of nucleotide substitution and the dynamic evolution of genome size (via double strand breaks). The dramatic shift in genome size and high mutation rates may have allowed for the variations observed in Utricularia bladder size, root structure, and relaxed body formation. Overall, the introduction of mutated COXI and high mutation rates provide a strong evolutionary hypothesis for the variability found in Utricularia species. Species Utricularia is the largest genus of carnivorous plants. It is one of the three genera that make up the Bladderwort family (Lentibulariaceae), along with the butterworts (Pinguicula) and corkscrew plants (Genlisea). This genus was considered to have 250 species until Peter Taylor reduced the number to 214 in his exhaustive study The genus Utricularia – a taxonomic monograph, published by Her Majesty's Stationery Office in 1989. Taylor's classification is now generally accepted with modifications based on phylogenetic studies (see below). The genus Polypompholyx, the pink petticoats, contained just two species of carnivorous plant, Polypompholyx tenella and Polypompholyx multifida, previously distinguished from the otherwise similar genus Utricularia