Utricularia Species Research Articles

Utricularia.

Whitewoods introduces the plant genus Utricularia.

Seasonal vegetation shift and wetland dynamics in vulnerable granitic rocky outcrops of Palghat Gap of southern Western Ghats, Kerala, India

Low altitude granitic hillock systems prevalent in Palghat (Palakkad) Gap region of southern Western Ghats were analyzed for seasonal dynamics in wetland taxa associated with marshy ephemeral flush vegetation, small ephemeral pools and deep rock pools. Due to characteristic habitat features, such systems harbor a unique pattern of microhabitats and associated floristic components. Wet phase in rocky outcrops in the monsoon season establishes a hydro-geomorphic habitat that supports establishment of wetland taxa like Eriocaulon, Drosera, Utricularia, Dopatrium, and Rotala. Seasonal shift in the floral associations was evident in tune with wetland dynamics. Wet rocks support ephemeral flush vegetation which display some unique plant associations of species of Eriocaulon, Utricularia, Drosera, Cyanotis, Murdannia, and Lindernia. Small ephemeral pools displayed taxa like Rotala malampuzhensis R.V. Nair, Dopatrium junceum (Roxb.) Buch.-Ham. ex Benth., D. nudicaule (Willd.) Benth., Monochoria vaginalis (Burm.f.) C. Presl, and Cyperus iria L. Rocky pools are the habitats of aquatic angiosperms like Nymphaea nouchali Burm. f., Ludwigia adscendens (L.) H. Hara, Utricularia aurea Lour. and Hydrilla verticillata (L.f.) Royle. The study documented 121 plant taxa from 37 families during a wet phase from rocky outcrops of the study area. Gradual shift in vegetation is evident as water recedes from granitic hillocks. During the period from December to March, the rocky pools dry up which results in a shift in the vegetation pattern where Poaceae members form the dominant elements. As most of the rocky outcrops are exposed to extreme temperature and acute water shortage, the taxa inhabiting such ecosystems tend to evolve much faster than in other habitats. Moreover, the vicinity of these hillocks in the Palghat Gap region to human settlements, face threats like fire, grazing, quarrying, dumping of wastes etc. which may cause considerable loss to the very sensitive plant communities which are not yet fully documented.

Floral micromorphology and nectar composition of the early evolutionary lineage Utricularia (subgenus Polypompholyx, Lentibulariaceae)

Utricularia (Lentibulariaceae) is a genus comprising around 240 species of herbaceous, carnivorous plants. Utricularia is usually viewed as an insect-pollinated genus, with the exception of a few bird-pollinated species. The bladderworts Utricularia multifida and U. tenella are interesting species because they represent an early evolutionary Utricularia branch and have some unusual morphological characters in their traps and calyx. Thus, our aims were to (i) determine whether the nectar sugar concentrations and composition in U. multifida and U. tenella are similar to those of other Utricularia species from the subgenera Polypompholyx and Utricularia, (ii) compare the nectary structure of U. multifida and U. tenella with those of other Utricularia species, and (iii) determine whether U. multifida and U. tenella use some of their floral trichomes as an alternative food reward for pollinators. We used light microscopy, histochemistry, and scanning and transmission electron microscopy to address those aims. The concentration and composition of nectar sugars were analysed using high-performance liquid chromatography. In all of the examined species, the floral nectary consisted of a spur bearing glandular trichomes. The spur produced and stored the nectar. We detected hexose-dominated (fructose + glucose) nectar in U. multifida and U. tenella as well as in U. violacea. In both U. multifida and U. tenella, there were trichomes that blocked the entrance into the throat and spur. Because these trichomes were rich in chromoplasts and contained lipid droplets, they may form an additional visual attractant. Bearing in mind the phylogenetic hypothesis for the genus, we suggest that an early ancestor of Utricularia had a nectariferous spur flower with a lower lip that formed a wide landing platform for bee pollinators.

DNA barcoding approach fails to discriminate Central European bladderworts (Utricularia, Lentibulariaceae), but provides insights concerning their evolution

The main features to distinguish the seven native Utricularia species occurring in central Europe are found in flower shape, but being rarely flowering identification is often doubtful and uncertain. A recent morphometric work highlighted that there are no univocal reliable extra-floral morphological features allowing a safe identification at species level. Therefore, DNA barcoding approach is attempted here. Molecular analyses were performed to search for DNA barcodes using nuclear ITS (rDNA), plastid (cpDNA) trnL-trnF IGS and rps16 intron sequences. Generally, the barcoding approach failed to discriminate Utricularia species, although it could be of some help in the U. minor aggregate. With few exceptions, U. bremii shows peculiar DNA regions different from U. minor for both plastid markers investigated. However, interesting hypotheses could be derived from the obtained networks, including hybridization events to explain the rise of mostly sterile species, such as U. stygia. This species clusters with the other species of the U. intermedia aggregate in plastid phylogenetic graphs, while it is closely related to species of the U. minor aggregate in ITS phylogenetic graphs. Additionally to U. stygia, U. ochroleuca also shows some incongruences in the different markers, at least for some accessions, pointing to the possible occurrence of hybrids.

The Trap Architecture of Utricularia multifida and Utricularia westonii (subg. Polypompholyx).

Utricularia are carnivorous plants which have small hollow vesicles as suction traps that work underwater by means of negative pressure and watertightness of the entrance for capturing small animal prey. Utricularia multifida and U. westonii have specific thick-walled traps, which are triangular in a transverse section but their functioning is unclear. Some authors suggest that the trap door in U. multifida acts as a simple valve without a suction trapping mechanism. Our main aim was to check the anatomical trap characters that are responsible for possible water outflow and maintaining negative pressure as main functional parts of the active trap suction mechanism in both species. Using different microscopic techniques, we investigated the ultrastructure of external trap glands, quadrifids, glands near the entrance (bifids, monofids), and also pavement epithelium. Quadrifids of both species have a similar structure to those known in other species from the genus, which possess the suction trap mechanism. Glands near the entrance in U. multifida and U. westonii, which are responsible for water pumping in other species, are typically developed as in other species in the genus and have pedestal cells which are transfer cells. The transfer cells also occur in glands of the pavement epithelium, which is again typically developed as in other species in the genus. Simple biophysical tests did not confirm reliably neither the negative underpressure formation in the traps nor the watertightness of the entrance in both species. Our anatomical results indirectly support the hypothesis that both species have suction traps like all other Utricularia species, but the biophysical data rather suggest a passive valve mechanism.

The Structure and Occurrence of a Velum in Utricularia Traps (Lentibulariaceae).

Bladderworts (Utricularia, Lentibulariaceae, Lamiales) are carnivorous plants that form small suction traps (bladders) for catching invertebrates. The velum is a cuticle structure that is produced by specialized trichomes of the threshold pavement epithelium. It is believed that the velum together with the mucilage seals the free edge of the trap door and that it is necessary for correct functioning of the trap. However, recently, some authors have questioned the occurrence of a velum in the traps of the Utricularia from the various sections. The main aim of this study was to confirm whether velum occurs in the traps of the Utricularia species from the subgenera Polypompholyx, Bivalvaria, and Utricularia. The 15 species were examined from subg. Polypompholyx, subg. Bivalvaria, and subg. Utricularia. A velum was found in all examined Utricularia species. In the traps of the members of section Pleiochasia, there was an outer velum (forming a complete ring) and an inner velum. In the traps of Utricularia uniflora (Lasiocaules), there was only an inner velum. In these species, the formation of the velum was accompanied by intensive mucilage production, and as a result, when door was closed (set position), the mucilage and the velum touched the surface of the door. In members of both sections of Pleiochasia and Lasiocaules, the pavement epithelium had a more complicated structure (four to five zones) than in the members of the subgenera Bivalvaria and Utricularia in which three distinct zones occurred (an outer with a velum, a middle and an internal with the mucilage trichomes). Even in U. purpurea, where the threshold was a reduced pavement epithelium, it consisted of three functional zones and the presence of a velum. Two main types of velum have been proposed. A velum was present in Utricularia traps regardless of the trap type or the habitat (aquatic, epiphytic, and terrestrial species). We proposed broad definition of velum as cuticle membranes covered by mucilage; from a functional point of view, this definition is more useful and more reflects complexity of this structure.

Germination rate and longevity of seeds of Aldrovanda vesiculosa and Utricularia vulgaris

The ecological group of aquatic carnivorous plants includes monotypic Aldrovanda vesiculosa L. (Droseraceae) and around 60 species of Utricularia L. (Lentibulariaceae). Although the majority of aquatic carnivorous species are perennials and propagate mainly vegetatively by branching, shoot fragmentation and turions, the majority of them also set seeds (Taylor 1989; Cross 2012; Cross et al. 2016, 2018). While these modes of vegetative propagation in temperate species ensure the production of high plant biomass at sites during each season and turions also serve population overwintering (Adamec 1999a, 2011), functional seeds form a viable seed bank as a safety measure to overcome crucial habitat disturbances (mainly drought) leading to biomass extinction and are usually spread by water birds to colonize new potential distant sites (Santamaria 2002; Cross 2012; Cross et al. 2016, 2018).

Pollen morphology of selected species of Lentibulariaceae Rich. from Western Cuba based on light microscopy and its taxonomic implications

We present here pollen morphology of 12 native taxa of Lentibulariaceae from Western Cuba with the aim of surveying pollen traits useful for species identification. Pollen grains were studied using light microscopy and scanning electron microscopy to search for new characteristics to contribute to the taxonomy of Lentibulariaceae from western Cuba with the aim of increasing our understanding of pollen morphology. Pollen grains were acetolysed, measured, photographed, and described based on qualitative characteristics. Here we present statistical analyses and multivariate statistics for quantitative data. The pollen grains are medium-sized, isopolar, subprolate to prolate, circular, subcircular to quadrangular amb, zonaperturate, 3-colporate, 4(5)-colporate, (6–)7–18-colporate or porate, lalongate or lolongate endoaperture, or endocingulate in some species. They may also be psilate, psilate-perforate, microreticulate to rugulate exine, and sexine thicker than nexine. Endoaperture with fastigia was reported for Pinguicula ser. Albidae and Lentibulariaceae for the first time in this study. The Utricularia species studied were grouped into three pollen types on the basis of aperture and endoaperture characteristics and shape. Morphological variations observed showed intergeneric pollen diversity in Lentibulariaceae, corroborating the taxonomic importance of such characteristics at a family level.

Delayed selfing ensures reproductive assurance in Utricularia praeterita and Utricularia babui in Western Ghats.

Numerous bladderwort (Utricularia) species are distributed worldwide, but their reproductive biology is rarely investigated. Bladderworts are known to depend on tiny organisms to meet a significant proportion of their energy requirement by trapping them in bladders. However, information on the extent of their reliance on insects for pollination success is limited. We examined the reproductive strategy of two Utricularia species viz. Utricularia praeterita and U. babui, endemic to Western Ghats, India. The main aspects of the investigation involved floral biology, breeding system, pollination mechanism, and reproductive success. Flowers of both the species are structured for outbreeding through entomophilous floral suites, herkogamy, protandrous dichogamy and sensitive lobes of the stigma. With nearly 65% natural fruit-set, both the species appeared to be sufficiently open-pollinated. However, pollinators failed to show in plants of U. praeterita while in U. babui there was an apparent mismatch between the extent of fruit-set and pollinator visits. The study demonstrated that in the absence/insufficient visits of pollinators, the two species resort to autonomous selfing. In U. babui, denser patches of plants appeared to be crucial for attracting the pollinators. Both species are self-compatible, and reproductive success is predominantly achieved by delayed autonomous selfing. The sensitive stigma in the species fails to prevent selfing due to diminished herkogamy during the late anthetic stages. It is inferred that in the pollinator-limited environment, delayed selfing contributes to absolute natural fecundity in U. praeterita, while it produces a mixed progeny in U. babui.

Are shoots of diagnostic value in Central European bladderworts (Utricularia L., Lentibulariaceae)?

In central Europe, seven native species of Utricularia occur, mainly distinguished by flower features. They can be subdivided in three aggregates according to shoot morphology: (1) Utricularia intermedia aggr., also comprising Utricularia ochroleuca and Utricularia stygia, (2) Utricularia vulgaris aggr., also comprising Utricularia australis and (3) Utricularia minor aggr., also comprising Utricularia bremii. We tested some shoot features as identification tools and investigated quadrifid digestive glands in all the studied species, using geometric morphometrics. For U. intermedia aggr., in most cases, the tooth number per ultimate leaf segment may be diagnostic. The three species of this aggregate overlap in terms of gland shape, but averaging measurements by traps and individuals, a decrease of overlapping among species was found. The shape and the centroid size of quadrifid glands in U. minor aggr. is unsuitable for discriminating species. Concerning U. vulgaris aggr., U. vulgaris bears a higher ratio of setula length to tooth length than U. australis (which is more toothed). This feature may help to distinguish species, but conflicting results were found in one studied population. The relevance of quadrifid gland features as identification tool and the puzzling systematic circumscriptions of the target species are discussed.

Nectar trichome structure of aquatic bladderworts from the section Utricularia (Lentibulariaceae) with observation of flower visitors and pollinators

In Utricularia, the flower spur is a nectary and in this organ, nectar is produced and stored. This study aimed to examine the structure of the nectary trichomes in four Utricularia species (Utricularia vulgaris L., U. australis R.Br., U. bremii Heer and U. foliosa L.) from the generic section Utricularia. We have investigated whether species with different spur morphology had similar spur anatomy and nectary trichome structure. In Utricularia flowers, nectar is produced by spur capitate trichomes (sessile or stalked). Our results showed that regardless of the various spur morphology, trichomes have similar architecture and ultrastructure. Head cells of these trichomes are transfer cells with an eccrine nectar secretion. Examined species differed in the micromorphology of papillae in spurs. The fly Eristalis tenax was found to be a pollinator of U. vulgaris. Small Halictidae bees seem to be pollinators of U. foliosa.

Accumulation of 137Cs by Carnivorous Aquatic Macrophytes (Utricularia spp.) on the Savannah River Site.

Plants are an important mode of transfer of contaminants from sediments into food webs. In aquatic ecosystems, contaminant uptake by macrophytes can vary by path of nutrient uptake (roots vs. absorption from water column). Carnivorous plants likely have additional exposure through consumption of small aquatic organisms. This study expanded on previous research suggesting that bladderworts (Genus Utricularia) accumulate radiocesium (137Cs) and examined for (1) a potential association between sediment and plant concentrations and (2) differences in 137Cs accumulation among rooted and free floating Utricularia species. A strong correlation was found between average 137Cs concentrations in all Utricularia species (combined) and sediments (rs=0.9, p=0.0374). Among three bladderwort species at common sites, Utricularia floridana, the only rooted species, had higher mean 137Cs concentrations than Utricularia purpurea, and U. purpurea had a greater mean 137Cs concentration than Utricularia inflata.

Molecular phylogeny of bladderworts: A wide approach of Utricularia (Lentibulariaceae) species relationships based on six plastidial and nuclear DNA sequences

The carnivorous plant genus Utricularia L. (bladderwort) comprises about 240 species distributed worldwide and is traditionally classified into two subgenera (Polypompholyx and Utricularia) and 35 sections, based mainly on general and trap morphology. It is one out of the largest carnivorous genera, representing ca. 30% of all carnivorous plant species, and is also the most widely distributed. According to previous phylogenetic studies, most infrageneric sections are monophyletic, but there are several incongruences considering their relationships and also the dissenting position of some species as a result of a too few (mostly one or two) molecular markers analyzed. Thus, here we present a multilocus phylogeny for Utricularia species with a wide taxonomic sampling (78 species and 115 accessions) based on six plastid (rbcL, matK, rpl20-rps12, rps16, trnL-F) and nuclear DNA (ITS region) sequences. The aim is to reconstruct a well-resolved tree to propose evolutionary and biogeographic hypotheses for the radiation of lineages with inferences about the divergence times of clades using a molecular clock approach.

Trap diversity and character evolution in carnivorous bladderworts (Utricularia, Lentibulariaceae)

Bladderworts (Utricularia, Lentibulariaceae, Lamiales) constitute the largest genus of carnivorous plants but only aquatic species (about one fifth of the genus) have so far been thoroughly studied as to their suction trap functioning. In this study, we comparatively investigated trap biomechanics in 19 Utricularia species to examine correlations between life-forms, trapping mechanisms, and functional-morphological traits. Our investigations show the existence of two functional trap principles (passive trap in U. multifida vs. active suction traps), and – in active suction traps – three main trapdoor movement types (with several subtypes). The trapdoor movement types and their corresponding functional-morphological features most presumably represent adaptations to the respective habitat. We furthermore give insights into fluid dynamics during suction in three representatives of the main types of trapdoor movement. The results on functional morphology and trapdoor movement were mapped onto a new phylogenetic reconstruction of the genus, derived from the rapidly evolving chloroplast regions trnK, rps16 and trnQ-rps16 and a sampling of 105 Utricularia species in total. We discuss potential scenarios of trap character evolution and species radiation, highlighting possible key innovations that enable such a unique carnivorous lifestyle in different habitats.

Vascular tissue in traps of Australian carnivorous bladderworts (Utricularia) of the subgenus Polypompholyx

Utricularia (bladderworts) are rootless carnivorous plants forming small suction traps which are hollow discoid bladders. There is some controversy surrounding the understanding of trap vascularization in Utricularia species and most of the knowledge in the literature is based on aquatic Utricularia from section Utricularia. In this study, we investigated trap vascularization in 9 Utricularia species or clones from the subgenus Polypompholyx using several light microscopy staining techniques. Both xylem and phloem elements were found in the traps of all investigated species or clones. The pattern of trap vascular bundles from the subgenus Polypompholyx was similar to that reported for subgenus Bivalvaria, but different from that of aquatic U. vulgaris from the subgenus Utricularia. The system of trap vascularization in the members of the subgenus Polypompholyx was different from that found in the traps of Genlisea, which is a closely related genus (both Lentibulariaceae). The structure of trap vascular bundles was, however, similar in Genlisea and Polypompholyx. Possible utilization of xylem elements in Utricularia traps is discussed.

Serial block face SEM visualization of unusual plant nuclear tubular extensions in a carnivorous plant (Utricularia, Lentibulariaceae).

In Utricularia nelumbifolia , the nuclei of placental nutritive tissue possess unusually shaped projections not known to occur in any other flowering plant. The main aim of the study was to document the morphology and ultrastructure of these unusual nuclei. In addition, the literature was searched to find examples of nuclear tubular projections in other plant groups, and the nuclei of closely related species of Utricularia (i.e. sects Iperua , Orchidioides , Foliosa and Utricularia ) were examined. To visualize the complexity of the nuclear structures, transmission electron microscopy (TEM) was used, and 3-D ultrastructural reconstructions were made using the serial block face scanning electron microscopy (SBEM) technique. The nuclei of 11 Utricularia species, i.e. U. nelumbifolia , U. reniformis , U. cornigera , U. nephrophylla (sect. Iperua ), U. asplundii , U. alpina , U. quelchii (sect. Orchidioides ), U. longifolia (sect. Foliosa ), U. intermedia , U. minor and U. gibba (sect. Utricularia ) were examined. Of the 11 Utricularia species examined, the spindle-like tubular projections (approx. 5 μm long) emanating from resident nuclei located in placental nutritive tissues were observed only in U. nelumbifolia . These tubular nuclear extensions contained chromatin distributed along hexagonally shaped tubules. The apices of the projections extended into the cell plasma membrane, and in many cases also made contact at the two opposing cellular poles, and with plasmodesmata via a short cisterna of the cortical endoplasmic reticulum. Images from the SBEM provide some evidence that the nuclear projections are making contact with those of neighbouring cells. The term chromatubules (chromatin-filled tubules) for the nuclear projections of U. nelumbifolia placental tissue was proposed here. Due to the apparent association with the plasma membrane and plasmodesmata, it was also speculated that chromatubules are involved in nucleus-cell-cell communication. However, further experimental evidence is required before any functional hypothesis can be entertained.

Measurement of the critical negative pressure inside traps of aquatic carnivorous Utricularia species

Firing and resetting of aquatic Utricularia traps are associated with water flows and pressure changes. A negative pressure of ca. −0.16bar is formed in reset traps, but its direct measurement is very difficult. We present a method of a gradual external application of negative pressure of −0.56 to −0.84mbars−1 through a fine capillary to cut off aquatic Utricularia traps to determine the critical negative pressure (CNP) at which the traps (located in air) fire and aspirate an air bubble. Using an electronic pressure sensor, we simulated the physiologically formed negative pressure needed for spontaneous trap firing in 15 aquatic Utricularia species of four generic sections. Mean CNP values ranged from −0.069bar in giant traps of U. reflexa to −0.346bar in U. dichotoma. The average in all 20 species or variants tested was −0.195±0.018bar, while that in 13 species or variants of the generic section Utricularia was −0.165±0.015bar and significantly differed from that of three populations of two species (U. dichotoma, U. volubilis) of the generic section Pleiochasia (−0.335±0.006bar). CNP differed significantly between giant and smaller traps of U. reflexa and young and old traps of U. vulgaris. Pooled data for 20 species or variants showed a significant negative linear correlation between trap length and CNP value. Within each species, high variability of the CNP was found: the lowest values were usually 2–3 times lower than the highest ones. This variability can represent three types of spontaneous firings described in the literature.

Lentibulariaceae from the Viruá National Park in the northern Amazon, Roraima, Brazil<br />

Lentibulariaceae is the family with the second highest number of species in the Viruá National Park (VNP) according to a recent floristic survey of the aquatic and palustrine angiosperms there. The aim of the present study is to provide identification material and information on those species of Lentibulariaceae. Species descriptions were based on recent vouchers collected by the authors and previous collections deposited in various herbaria. We present keys, brief descriptions and images, comments on morphology and the geographic distribution of three species of Genlisea and 22 species of Utricularia. The eight new occurrences raise the number of known species for the family in Roraima to 39. The species composition of the Lentibulariaceae in VNP shows a close similarity with that one of the family on the Guiana Shield.

Biology of the trapless rheophytic Utricularia neottioides: Is it possible to grow this specialized species in cultivation?

The nearly trapless aquatic bladderwort Utricularia neottioides is one of the most remarkable and curious Utricularia species, growing attached to bare rock in streams of South America. It has never been cultivated due to its rheophytic habit and unknown ecological demands. As late as in 2012, one of us (KP) was able to grow this species in tissue culture from seed, so that the species has become available for cultivation and for anatomical and ecophysiological investigations. In this paper, we describe the biology of the species based on observations made in natural habitat and cultivation, its growth in in-vitro and ex-vitro, and raise the question whether it can be grown long-term ex vitro at all.

Two new species of Utricularia (Lentibulariaceae) from the North West region of Western Australia

Two new species of Utricularia (Lentibulariaceae) from the North West region of Western Australia. Utricularia
 byrneana R.W.Jobson & Baleeiro and U. wannanii R.W.Jobson & Baleeiro are described as new and are considered
 members of Utricularia subgen. Polypompholyx section Pleiochasia. The distribution and habitat preferences
 of these species are discussed. Two individual taxonomic keys are provided representing the groups in which
 the new species are most likely to be closely related. Specifically, Utricularia byrneana is compared with species
 from Western Australia possessing hollow peduncles namely U. fistulosa P.Taylor and U. tubulata F. Muell.,
 while U. wannanii is compared to species possessing connate bracts and bracteoles namely U. dunlopii P.Taylor,
 U. georgei P.Tayor and U. kimberleyensis C.A.Gardener, as well as close relative U. uniflora R.Br.