The genus Utricularia includes around 250 species of carnivorous plants, commonly known as bladderworts. The generic name Utricularia was coined by Carolus Linnaeus in reference to the carnivorous organs (Utriculus in Latin) present in all species of the genus. Since the formal proposition by Linnaeus, many species of Utricularia were described, but only scarce information about the biology for most species is known. All Utricularia species are herbs with vegetative organs that do not follow traditional models of morphological classification. Since the formal description of Utricularia in the 18th century, the trap function has intrigued naturalists. Historically, the traps were regarded as floating organs, a common hypothesis that was maintained by different botanists. However, Charles Darwin was most likely the first naturalist to refute this idea, since even with the removal of all traps, the plants continued to float. More recently, due mainly to methodological advances, detailed studies on the trap function and mechanisms could be investigated. This review shows a historical perspective on Utricularia studies which focuses on the traps and body organization.

Phylogenetic relationships among all of the 47 recognised species and 10 putative new taxa of Utricularia subgenus Polypompholyx, were assessed using maximum parsimony and Bayesian inference analyses of DNA sequences representing the plastid rps16 intron, trnL–F intron and spacer regions and the trnD–T intron. We found strong jackknife and posterior-probability support for a monophyletic subgenus Polypompholyx and a sister relationship between the sections Polypompholyx + Tridentaria and Pleiochasia. Within the section Pleiochasia, are two well-supported major clades, each containing three supported clades. Our S-DIVA biogeographic analysis, using five major Australian drainage basins and New Zealand as geographic areas, estimated two early vicariance events between south-western and north-western mainland regions, corresponding with known periods of increased aridity at 15 and 6 million years ago. Subsequent dispersal events were estimated between northern and south-eastern Australia, with recent dispersal of species from south-western regions to the south-east and New Zealand occurring between 4 million and 1 million years ago. There were 28 speciation events inferred within the north-western region, followed by 9 for the south-western and south-eastern regions, indicating that the north-western monsoonal savanna habitats are a biodiversity hotspot for the lineage. We also show the evolutionary shifts in growth habit, and show that lifecycle corresponds strongly with shifts in seasonality between temperate and monsoonal regions. On the basis of our molecular phylogenetic results and morphology, we here designate a new sectional ranking for subgenus Polypompholyx.

The terrestrial carnivorous speciesUtricularia dichotomais known for a great phenotypic plasticity and unusual vegetative organs. Our investigation on 22 sources/populations revealed that after initiation of a leaf and two bladders on a stolon, a bud was formed in the proximal axil of the leaf, developing into a rosette with up to seven organs. The first two primordia of the bud grew into almost every possible combination of organs, but often into two anchor stolons. The patterns were generally not population specific. The interchangeability of organs increased with increasing rank in the succession of organs on stolon nodes. A high potential of switching developmental programs may be successful in a fluctuating environment. In this respect, we were able to show that bladders developed from anchor stolons experimentally when raising the water table. Anatomical structures were simple, lacunate and largely homogenous throughout all organs. They showed similarities with many hydrophytes, reflecting the plant’s adaptation to (temporarily) submerged conditions. The principal component analysis was used in the context of dynamic morphology to illustrate correlations between organ types in the morphospace ofU. dichotoma, revealing an organ specific patchwork of developmental processes for typical leaves and shoots, and less pronounced for a typical root. The concept and methods we applied may prove beneficial for future studies on the evolution of Lentibulariaceae, and on developmental morphology and genetics of unusual structures in plants.

Phylogenetic relationships among 26 of the 37 recognised taxa of Utricularia subgenus Polypompholyx sensu Müller & Borsch were assessed by cladistic analysis of DNA sequences from the plastid rps16 intron. We also examined the placement of the recently described U. simmonsii (sect. Minutae), which was reported to share some morphological characters with subgenus Polypompholyx. We found strong jackknife support for a monophyletic subgenus Polypompholyx lineage; however, our strict consensus tree shows an unresolved relationship between the sections Polypompholyx and Pleiochasia. Within the section Pleiochasia, we found two supported clades, generally differing in a more northern or southern distribution. Despite high levels of morphological heterogeneity and convergence, we found some clade-specific character homogeneity within these two clades, particularly that of growth and bladder-trap form, and floral structure. Bladder-trap form corresponds most strongly with terrestrial v. aquatic habits. The evolution of filiform corolla appendages corresponds with floral colour, and is possibly associated with sexual mimicry, with those of the upper corolla arising twice independently. Furthermore, we found that U. monanthos and U. novae-zelandiae remain synonyms of U. dichotoma, and that U. simmonsii is not included in the subgenus Polypompholyx, but instead is allied with sections Stomoisia and Enskide of subgenus Bivalvaria.

Aims: The carnivorousUtricularia(Lentibulariaceae) has an anatomically simple and seemingly rootless vegetative body. It occupies a variety of wetlands and inland waters and shows a broad range of life forms. Here, we aimed to elucidate structural and functional traits in various hydric conditions. Furthermore, we intended to evaluate morpho-anatomical adaptations in correlation with life forms.Methods: Morpho-anatomical characteristics typical for hydrophytes of all life forms were investigated by light microscopy on 13Utriculariataxa, compared to onePinguiculaand twoGenliseataxa, and assessed by multivariate analyses.Results: Vegetative structures ofUtriculariaandGenliseashowed reduced cortical, supporting, and vascular tissues. With increasing water table, leaves were thinner, and narrower or dissected, and submerged organs tended to contain chloroplasts in parenchymatic and epidermal cells. In some main stolons, an endodermis with Casparian strips was visible. Large gas chambers, including a novel ‘crescent’ and a special ‘hollow’ aerenchyma pattern, were found in amphibious to free-floating taxa.Conclusions: The evolutionary transfer of carnivory from aerial to subterranean organs inGenlisea, and even more inUtricularia, coincides with a highly simplified anatomy, which is adapted to a broad variety of hydric conditions and compensates for structural innovations in the uptake of nutrients.

The occurrence of the carnivorous plant Utricularia dichotoma (including U. monanthos and U. novae‐zelandiae ) within different habitats throughout New Zealand was studied. Qualitative investigations on its ecology focused on plant sociological criteria and soil characters, including the qualitative amount of water and soil chemistry. A list of associated plant species is also provided. Results indicate that U. dichotoma prefers open wet habitats. Once established, however, it may grow in fertile and permanently submerged sites. The vegetative morphology of the species from different populations was also examined and correlated with ecological factors. Utricularia dichotoma basically consists of runner stolons, from each node of which arise various combinations of leaves, bladders (traps), and anchor and runner stolons. Plants of some populations also show simply branched, bladder‐bearing intermediate types of anchor and runner stolons (designated “simple stolons”). Some nodes of runner stolons support the development of a peduncle. In the populations studied, the onset of a dry sunny period was typically followed by flowering. Plants from Kopouatai Peat Dome exhibited certain distinctive morphological features not found in other populations, including more bladders per plant. Among the populations studied, the corolla, peduncle, foliage leaf, and bladders occasionally exhibited a reddish or purple pigmentation, apparently developed in a response to different environmental factors.