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Floral nectar is mainly a reward in the form of food for pollinators. In early spring, when snow can still be present, pollinators have trouble finding food. The composition and productivity of nectar in flowers play an important role in a pollinator's life. It is known that low temperatures and lower humidity cause lower nectar secretion. Some studies have also shown that the quality of nectar can differ because of lower temperatures. In our research, we analysed whether abiotic factors affect nectar secretion, as well as the nectar composition of the early spring plant species Galanthus nivalis L. and Helleborus niger L. in February 2024. The study was conducted in two locations in nature. Nectar from H. niger was sampled in Tomišelj, Slovenia, whereas nectar from G. nivalis was sampled in Ljubljana, Slovenia. On four different days at three different times of day, we sampled nectar from flowers using microcapillaries. In total, we sampled 48 nectar samples from one species. We analysed soil humidity and temperature, air temperature and humidity, and UVB radiation. Our results show that nectar productivity is highest in the morning for both species. H. niger has sucrose-dominant nectar, while G. nivalis has hexose-dominant nectar. Proline, which is an important amino acid for bees, has the highest level in both species, as does the phenolic compound rutin. Environmental factors do affect nectar secretion. Soil and air temperature affect G. nivalis nectar secretion, while soil humidity affects H. niger nectar secretion. Soil and air temperature also have an effect on higher levels of sugars in both researched nectars. UVB, air humidity, and air and soil temperature seem to have an effect on phenolic compounds, but abiotic factors do not affect amino acids. [ABSTRACT FROM AUTHOR]

Floral nectar is mainly a reward in the form of food for pollinators. In early spring, when snow can still be present, pollinators have trouble finding food. The composition and productivity of nectar in flowers play an important role in a pollinator’s life. It is known that low temperatures and lower humidity cause lower nectar secretion. Some studies have also shown that the quality of nectar can differ because of lower temperatures. In our research, we analysed whether abiotic factors affect nectar secretion, as well as the nectar composition of the early spring plant species Galanthus nivalis L. and Helleborus niger L. in February 2024. The study was conducted in two locations in nature. Nectar from H. niger was sampled in Tomišelj, Slovenia, whereas nectar from G. nivalis was sampled in Ljubljana, Slovenia. On four different days at three different times of day, we sampled nectar from flowers using microcapillaries. In total, we sampled 48 nectar samples from one species. We analysed soil humidity and temperature, air temperature and humidity, and UVB radiation. Our results show that nectar productivity is highest in the morning for both species. H. niger has sucrose-dominant nectar, while G. nivalis has hexose-dominant nectar. Proline, which is an important amino acid for bees, has the highest level in both species, as does the phenolic compound rutin. Environmental factors do affect nectar secretion. Soil and air temperature affect G. nivalis nectar secretion, while soil humidity affects H. niger nectar secretion. Soil and air temperature also have an effect on higher levels of sugars in both researched nectars. UVB, air humidity, and air and soil temperature seem to have an effect on phenolic compounds, but abiotic factors do not affect amino acids.

Background: Complementary treatment options for tumors and hematological malignancies constitute a strong therapeutic need. Medicinal plant extracts from Helleborus niger L. and Helleborus foetidus L. are effective in corresponding clinical applications, but their composition and bioactivity still await further investigations. Due to their cytotoxicity, saponins and protoanemonin might be related to effectiveness of pharmaceutical extracts from H. niger and H. foetidus. Purpose: The goal of this study was to evaluate the cytotoxic and apoptosis-inducing capacity of different pharmaceutical extracts from H. niger and H. foetidus in selected in-vitro assays and to compare their protoanemonin and saponin concentration levels. Methods: Aqueous extracts from H. niger and H. foetidus were obtained according to two different pharmacopoeial methods as stated in European Pharmacopoeia and German Homoeopathic Pharmacopoeia. Cytotoxic and apoptosis inducing activities of extracts were analyzed using tumor cell lines MOLT4, SK-UT-1b and HT-144, as well as cultured human PBMC. Protoanemonin and saponin concentrations were determined by HPLC-DAD analysis. Results: Saponin and protoanemonin contents were different dependent on the pharmacopoieal method applied, as well as on the plant species and parts used for extract production. Maceration according to Ph. Eur. 1.3.1 yielded extracts with almost opposite protoanemonin and saponin contents from H. foetidus and H. niger (H. foetidus: low saponin level, high protoanemonin level; H. niger: vice versa). Fermented H. niger extracts showed saponin and protoanemonin contents ranging between those of the Ph. Eur. 1.3.1 extracts from both species. Both H. niger and H. foetidus extracts exhibited cytotoxicity in the selected cell line assays. H. foetidus extract was about 10 times more cytotoxic than H. niger extract. Investigated cell lines showed different responses towards the pharmaceutical extracts. Tumor cells were more prone to apoptosis induction than human PBMC cells. Conclusions: The present investigation demonstrates that the contents of protoanemonin and saponins in the medicinal plant extracts from studied Helleborus sp. differ significantly. While both plant extracts were found to be cytotoxic against selected tumor cells, H. foetidus exhibited much stronger cytotoxic activities than H. niger. The individual metabolic profiles of saponins and protoanemonin in H. niger and H. foetidus could contribute to these differences in cytotoxic potential. To obtain defined plant extracts for medicinal purposes it is essential to use official manufacturing procedures and accurately specified plant species and parts.

Helleborus atrorubens is an economically important perennial garden plant with medicinal value. Here, we sequenced the complete chloroplast genome of H. atrorubens. The results revealed the chloroplast genome to be 166,695 bp in length. It possesses a typical quadripartite structure containing one large single copy (LSC) region (84994 bp), one small single copy (SSC) region (17,825 bp), and a pair of inverted repeat (IR) regions (31938 bp). This chloroplast genome encoded 130 genes, out of which 85 code for proteins, 37 for transfer RNAs, and 8 for ribosomal RNAs. Simple sequence repeat (SSR) markers and the top variable coding regions were identified. Our study lays a foundation for further research, such as species differentiation and phylogenetic reconstruction of the Helleborus genus.

Helleborus atrorubens is an economically important perennial garden plant with medicinal value. Here, we sequenced the complete chloroplast genome of H. atrorubens. The results revealed the chloroplast genome to be 166,695 bp in length. It possesses a typical quadripartite structure containing one large single copy (LSC) region (84994 bp), one small single copy (SSC) region (17,825 bp), and a pair of inverted repeat (IR) regions (31938 bp). This chloroplast genome encoded 130 genes, out of which 85 code for proteins, 37 for transfer RNAs, and 8 for ribosomal RNAs. Simple sequence repeat (SSR) markers and the top variable coding regions were identified. Our study lays a foundation for further research, such as species differentiation and phylogenetic reconstruction of the Helleborus genus. [ABSTRACT FROM AUTHOR]

Summary The tricks of stinking hellebore The stinking hellebore (Helleborus foetidus) uses ingenious tricks in order to attract pollinators and to achieve the dispersal of its seeds. Yeasts metabolise sugar available in nectar und thereby warm it up to attract bees and bumble bees in cold, early spring. This remarkable heating system allows the flowers to already attract pollinators at a time, when competition by other flower species is still low and visits by pollinators are often limited by low temperatures. Early flowering in turn allows seed set in late spring and early summer. The seeds have a fleshy structure attached, an elaiosome that contains lipids, sugars and vitamins. This makes them highly attractive to ants during a season when high‐quality foods are still in short supply and leads to dispersal of the seeds (myrmecochory). The elaiosome also contains a fatty acid that acts as an olfactory attractant. But what attracts ants, is also attractive for other seed predators such as mice. Long‐term survival of seeds (and thus germination) therefore greatly depends on the detachment of the elaiosome from the seed by the ants. There is much more than meets the eye with respect of stinking hellebore pollination and seed dispersal. It is an example of the highly complex interdependencies between plants, their blossoms, different animal species as well as yeasts and bacteria. [ABSTRACT FROM AUTHOR]

The genus Helleborus belongs to the Ranunculaceae family, distributed in southeastern Europe and western Asia. In folk medicine, it is commonly used as an anti-inflammatory and analgesic medicine for rheumatoid arthritis and bruises. Through reviewing recent articles, it was found that two hundred and twenty-six compounds have been isolated and identified from the genus Helleborus . These compounds include steroids, flavonoids, phenylpropanoids, lignans, anthraquinones, phenolics and others. Among them, the main chemical constituents are steroids. Pharmacological studies show Helleborus has anti-cancer, immunomodulatory, anti-inflammatory, analgesic, anti-hyperglycaemic, antioxidant and antibacterial properties. This article reviews the botany, phytochemistry, pharmacological effects and clinical applications of the genus Helleborus . Hopefully, it will provide a reference for in-depth research and exploitation of the genus Helleborus .

Background: Long-term survival of children with cancer has reached rates of up to 80%. Nevertheless, continued research devoted to further improvement of survival rates especially for patients with high-risk illnesses is necessary. Recent studies have shown direct positive effects on tumor reduction through Viscum album (mistletoe) extracts in adults, mainly as a result of higher dosage treatment and intravenous or intratumoral application.Patients and Method: A retrospective analysis of data was carried out of all oncological, pediatric patients treated with intravenous high-dose mistletoe therapy for a period of two years (11/2013-11/2015).Results: A total of ten non-coherent cases were examined, all suffering from advanced and/or relapsed forms of cancer (leukemia, neuroblastoma, nephroblastoma, osteosarcoma, lymphoma, anaplastic astrocytoma, atypical teratoid rhabdoid tumor and soft tissue sarcoma). Patients were treated for an average period of 48 days with a mean survival rate of 130 days after beginning the mistletoe therapy. Partial remission was observed in four and a slowed disease progression was monitored in two patients. However, unrestricted progression of disease was documented in two other patients. Patients showed side effects including fever as well as fatigue and in some cases systemic inflammatory reactions with transient organ impairment occurred.Conclusion: Our study underpinned the safety and feasibility of high-dose mistletoe infusion in children with advanced stages of cancer and showed noteworthy antineoplastic effects, which should be verified in a prospective clinical phase II/III-study. Because of possible side effects, the treatment should be implemented only in an in-patient setting in experienced pediatric oncology centers. [ABSTRACT FROM AUTHOR]

Phytochemical reinvestigation of the dried roots and rhizomes of Helleborus thibetanus afforded four new minor spirostanol glycosides (1–4) and four known spirostanol glycosides (5–8). Their structures were determined on the basis of spectroscopic analyses, including 1D and 2D NMR experiments, together with HR-ESI-MS and IR measurements and the results of acid hydrolysis. [ABSTRACT FROM AUTHOR]

Four new minor spirostanol glycosides ( 1–4 ) were isolated from the dried roots and rhizomes of Helleborus thibetanus. Structures of the compounds were established by means of a combination of 1D and 2D NMR experiments, together with HRESIMS and IR measurements as well as the results of acid hydrolysis. The spirostanol glycosides with both a double bond at C-25 and glycosidation at 1-OH have seldom been reported. [ABSTRACT FROM AUTHOR]

Three new steroidal saponins including two spirostanol glycosides (1–2) and one furostanol glycoside 1-sulphate (3) were isolated from the dried roots and rhizomes ofHelleborus thibetanus. Structures of the compounds were determined on the basis of extensive use of 1-D and 2-D NMR experiments, together with HR–ESI–MS and IR measurements, as well as the results of acid hydrolysis. Compounds1–2represented steroidal saponins with an unusual substitution pattern, which possessed a double bond at C-25 and were glycosylated at 1-OH. [ABSTRACT FROM PUBLISHER]

The genus Helleborus is represented in the Northwestern Balkans by 8 species. Some of them (H. atrorubens, H. foetidus (newcomer, introduced as well as escaped from culture), H. niger, and H. orientalis (newcomer, escaped from culture)) are rather easy for determination and discrimination. While other 4 species (H. dumetorum, H. multifidus, H. odorus, and H. viridis) are really difficult for determination because of their narrow morphological similarity, which also is realized a wide variety in leaf shape. The distribution areas of last 4 species overlap in the Northwestern Balkans, so that there are no really clear borders of their distribution. Dominating species in this region is H. multifidus, and especially common there is its subsp. istriacus. Other 3 species are rare and are therefore often overlooked and the herbarium specimens are frequently misidentified as H. multifidus. Moreover, all these 4 species produce number of hybrids, and as a result all kind of transistions between these taxa could be found. In particular, 11 hybrides could be confirmed for this region. The hybrid between H. dumetorum and H. multifidus is described here as Helleborus ×mucheri. [ABSTRACT FROM AUTHOR]

Steroidal saponins comprise a substantial part of the secondary metabolite spectrum in the medicinal plant Helleborus niger L. (black hellebore). The saponin fraction from the roots was investigated by LC–MS n resulting in 38 saponins and β-ecdysone. Nine diosgenyl-type glycosides, mainly furostanols consisting of the aglycones diosgenin, macranthogenin, sceptrumgenin, and sarsasapogenin were accompanied by 5 diosgenyl-type saponins exhibiting an aglycone with an additional OH group. However, the most relevant compounds were 24 acetylated polyhydroxy saponins including hellebosaponins A and D. The enzymes glucuronidase, β-glucosidase, and pectinase were used to obtain an idea on potential fermentative transformation reactions by incubation of the isolated model saponins macranthosid I and hellebosaponin A. In a second step, aqueous H. niger extracts containing a much greater range of saponins were monitored during fermentation and 12 months of storage. The metabolites were examined and assigned by LC–MS n and targeted extracted ion current (EIC) scan analyses. Good agreement was found among the results from the model compounds and the whole aqueous fermented extracts. The native diosgenyl-type furostanol saponins were converted to spirostanols under scission of hexoses. Alteration of the acetylated polyhydroxy saponins, exclusively spirostanols, took place following cleavage of acetyl groups and terminal deoxyhexoses. Most interestingly, the pentoses of the sugar chain at C(1) were not affected. Conversion of acetylated polyhydroxy saponins resulted in a final structure type which was stable and detectable, even after 12 months of fermentation and storage. [ABSTRACT FROM AUTHOR]

Two new bufadienolides, 3β,14β,16β-trihydroxy-5α-bufa-20,22-dienolide ( 1 ) and 14β-hydroxy-3β-[β-D-glucopyranosyl-(1→6)-(β-D-glucopyranosyl)oxy]-5α-bufa-20,22-dienolide ( 2 ), one new pregnane, 3β-hydroxypregna-5,16-diene-20-one-1β-yl sulfate ( 3 ), along with one known pregnane ( 4 ) were isolated from the dried roots and rhizomes of Helleborus thibetanus . Their structures were elucidated by the extensive use of 1D and 2D NMR experiments, together with IR and HRESIMS spectra and the results of enzymatic hydrolysis. [ABSTRACT FROM AUTHOR]

Yeasts frequently colonise floral nectar, where they can reach high densities. Recent investigations have further shown that yeast metabolism alters nectar properties by decreasing its total sugar content, modifying sugar composition, or raising nectar local temperature. However, the distribution patterns of nectar yeasts remain poorly investigated at multiple spatial and temporal scales. Here, we study natural variation of the nectar yeasts in a single host plant, Helleborus foetidus , in a mountainous region. We quantified spatio-temporal variation in the frequency and abundance of yeast species across six populations located along an altitudinal gradient. Variance partitioning techniques were used to estimate the relative magnitude of variation in yeast abundance between individual plants, flowers within plants, and nectaries within flowers. Although yeast frequency and abundance varied widely across sites and dates, the largest part of total variance occurred at the sub-individual level (i.e., flowers on the same plant). Pollinator composition and activity seemed the main factors explaining the observed patterns of yeast frequency and abundance across floral nectar samples. [ABSTRACT FROM AUTHOR]

Despite their known toxic properties, various Helleborus species are used as medicaments in folk medicine to treat some diseases and health conditions. As the main mechanism of many cytostatic drugs is based on their cytotoxic activity, there is potential for the toxicity of hellebore to be used in anticancer therapy. This study tested the geno- and cytotoxic effects of extracts of three hellebore taxa (Helleborus odorus, Helleborus multifidus and Helleborus hercegovinus) on meristemic onion (Alliumcepa L.) cells and human lymphocytes. Treatments with Helleborus extracts induced cytotoxic and cytostatic effects in meristemic onion cells as well as in cultivated cytokinesis-blocked human lymphocytes. Cytokinesis-block micronucleus cytome assay indicated that treatments with hellebore extracts induce genotoxic effects in human lymphocytes, and that the significant mechanism of their antiproliferative activity is apoptosis induction. [ABSTRACT FROM AUTHOR]

Helleborus atrorubens is an economically important perennial garden plant with medicinal value. Here, we sequenced the complete chloroplast genome of H. atrorubens . The results revealed the chloroplast genome to be 166,695 bp in length. It possesses a typical quadripartite structure containing one large single copy (LSC) region (84994 bp), one small single copy (SSC) region (17,825 bp), and a pair of inverted repeat (IR) regions (31938 bp). This chloroplast genome encoded 130 genes, out of which 85 code for proteins, 37 for transfer RNAs, and 8 for ribosomal RNAs. Simple sequence repeat (SSR) markers and the top variable coding regions were identified. Our study lays a foundation for further research, such as species differentiation and phylogenetic reconstruction of the Helleborus genus., Competing Interests: No potential conflict of interest was reported by the author(s)., (© 2022 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.)

Abstract: The increased horticultural interest in Helleborus requires the development of techniques for flowering control. Therefore, we have determined flower initiation and differentiation under natural conditions for Helleborus niger L. and the hybrid Helleborus x ericsmithii B. Mathew. Once flower primordia were present in the underground buds of the plants, the effect of a cold treatment (336, 504 or 672 chilling units (CU)) and a supplemental gibberellic acid (GA3) application (500mgL−1) on pre-cooled plants was examined. The cold treatment resulted in a progressive decrease of the time to flower. Moreover, when pre-cooled plants received a supplemental GA3 application early flowering was further enhanced and these plants had a higher number of flowers with longer flower stems and larger flowers. [Copyright &y& Elsevier]

This study was undertaken in order to evaluate possible antioxidative and antiproliferative activities of three Helleborus taxa. The dry leaves and roots of three Helleborus taxa were extracted with ethanol and water. A phytochemical evaluation of the selected extracts was performed using spectrophotometric methods and a 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity assay was used for measuring the antioxidative activity of extracts. The antiproliferative activity of the three Helleborus taxa was studied using Burkitt's lymphoma B cells (BJAB) cell lines. The phytochemical evaluation showed that the leaves contain high levels of total phenolic and flavonoid content. Results from the DPPH assay indicated that the activity of the ethanol and water extracts of the leaves was higher than that of positive control (thymol). Extracts from the roots of H. odorus also displayed higher antioxidant activity than the positive probe, while H. mulifidus and H. hercegovinus root extracts were less effective. A statistically significant correlation between total phenolic content and antioxidative properties indicates that these compounds contribute to the antioxidant activity. The highest percentage of cell growth inhibition was observed when testing the water root extracts of H. multifidus (50.14%) and H. hercegovinus (49.04%). In contrast, the water leaf extract of H. hercegovinus exhibited the lowest inhibition of cell growth (8.59%), although it showed strong antioxidant activity. [ABSTRACT FROM PUBLISHER]

Abstract: Helleborus is a genus of herbaceous perennials belonging to the family Ranunculaceae. Within this genus six sections with a total of 22 species are found. The largest section Helleborastrum contains 16 species for which genetic relationships are still unclear. This study represents the first genetic analysis in the genus Helleborus, including the two newly described species H. liguricus and H. abruzzicus based on multilocus amplified fragment length polymorphism (AFLP) markers with a genome-wide distribution in combination with nuclear DNA content data. Chromosome analyses of roots tips revealed a number of 2n =32 for the selected species, which was congruent with previous observations. The nuclear DNA content of Helleborus was estimated by flow cytometry applying propidium iodide staining and varied between 18 and 33pg/2C, depending on the species. For AFLP analyses, 19 out of the 22 Helleborus species were studied using 10 AFLP primer combinations, resulting in a total of 1109 polymorphic bands among all species including the outgroup. The genetic distances between species varied between 0.034 and 0.330. Based on genetic distances a phenogram using the Neighbor-joining cluster method with bootstrap analysis was calculated. The results support the previously suggested division of the genus into six sections and thereby approve AFLP data to be applicable for phenetic analyses. Moreover, this genetic information is significant for the development of future Helleborus breeding strategies. [Copyright &y& Elsevier]

Abstract: We studied biotic and abiotic factors that influence pollination in two sympatric winter flowering species. Helleborus foetidus and Helleborus bocconei flower simultaneously in winter. Although climatic conditions are not favorable for biotic pollination both species rely mainly on large bees of the genus Bombus. At the beginning of flowering, harsh climatic conditions are restrictive for insect visits. As flowering continues and temperatures rise, pollinator activity increases. The two plant species share pollinators that visit them indiscriminately. The flowers of the two species differ in form and insects visit H. foetidus by inserting their heads and H. bocconei ventrally: pollen load on insects is highly specialized. With the arrival of spring, many other species start to bloom and in spite of the large number of flowers still on the plants insects abandon Helleborus species. At the end of spring increasing biotic interactions take away pollinators from the Helleborus species. [Copyright &y& Elsevier]

Abstract: Two new bufadienolide glycosides with an A/B trans ring structure, 14β,16β-dihydroxy-3β-(β-d-glucopyranosyloxy)-5α-bufa-20,22-dienolide (1), and 14β,16β-dihydroxy-3β-[β-d-glucopyranosyl-(1→4)-(β-d-glucopyranosyloxy)]-5α-bufa-20,22-dienolide (2), two known ecdysteroids (polypodine B and 20-hydroxyecdysone) (3-4), and six known bufadienolide and its glycosides with 5β-OH (hellebrigenin, 16β-hydroxyhellebrigenin-3-O-α-l-rhamnoside, hellebrigenin 3-O-β-d-glucoside, hellebrin, 16β-hydroxyhellebrigenin-3-O-β-d-glucoside, and deglucohellebrin) (5-10) were isolated from the rhizomes of Helleborus thibetanus. The structures of compounds 1 and 2 were elucidated using various spectroscopic methods. All compounds were reported for the first time from the title plant and their chemotaxonomic significance for the genus Helleborus was discussed. [ABSTRACT FROM AUTHOR]

Helleborus species are members of the family of the Ranunculaceae. These popular perennials are all diploids (2 n = 2 x = 32). This study investigates polyploidy induction by different antimitotic agents. Colchicine, oryzalin and trifluralin were tested in vitro on shoots of Helleborus niger, H. orientalis and H. × nigercors. Furthermore the effect of the antimitotic agents on the viability and the multiplication rate of cultured plantlets were analyzed. Flow cytometry demonstrated that polyploidisation was genotype dependent: using H. niger, tetraploids were obtained using either oryzalin (3 μM) or trifluralin (3 or 10 μM), whereas for H. × nigercors only trifluralin (3 or 10 μM) induced polyploidisation. For H. orientalis neither treatment was effective to produce tetraploids or mixoploids. For these three species, colchicine (100 μM) was ineffective. The polyploidisation events in H. niger and H. × nigercors were confirmed by chromosome counts of mounted nuclei derived from root tips (2 n = 4 x = 64). [ABSTRACT FROM AUTHOR]

The karyotypes of 16 species and one variety representing nine genera in the Ranunculaceae were analysed in order to obtain information on the placement of the genera Beesia and Eranthis at tribal rank in the family. Those of Beesia, Anemonopsis, Souliea, Cimicifuga, Actaea and Eranthis were found to be very similar to each other, but remarkably different from those of Caltha, Calathodes, Megaleranthis and Trollius with respect to chromosome size and morphology. From cytological data it is clearly evident that Beesia and Eranthis have a much closer affinity to Anemonopsis, Souliea, Cimicifuga and Actaea in the tribe Cimicifugeae than to Caltha, Calathodes, Megaleranthis and Trollius, which generally have been placed together in a single tribe, albeit with different tribal names such as Caltheae, Trollieae and Helleboreae. Therefore, Beesia and Eranthis may find better placement in the tribe Cimicifugeae. The long-presumed, mainly morphology-based close affinity between Eranthis and Helleborus is not supported by both cytological and palynological data. Cytologically, both Actaea and Eranthis appear to be the specialized genera in the Cimicifugeae, through having the most asymmetrical karyotypes in this tribe. Our results strongly support the recent re-definition of the tribe Actaeeae (as Cimicifugeae) to include Beesia and Eranthis, based on maximum parsimony analysis performed separately on molecular data. © 2006 The Linnean Society of London. Botanical Journal of the Linnean Society, 2006, 150, 267–289. [ABSTRACT FROM AUTHOR]

The duration of pollen exposure and female receptivity in the winter floweringHelleborus bocconeiTen. andHelleborus foetidusL. were determined in the field. Experimental treatments were performed “in vitro” on cultivated flowers in order to investigate the abiotic factors regulating the patterns of pollen presentation and stigma receptivity. Correlation analysis with meteorological data in the field and the experimental results demonstrated temperature to be the main factor affecting the duration of anthesis and the number of anthers opening each day, whereas the duration of female receptivity mainly depends on whether or not pollination had occurred. This features may be an adaptation that allows biotic pollination under harsh environmental conditions. [ABSTRACT FROM AUTHOR]

In addition to the green leaves, commonly considered as the main sources of photosynthate production, higher plants can potentially use nearly all vegetative and reproductive structures to perform photosynthetic CO2 assimilation. Green leaves, stems and green sterile flower organs, optimized for light harvesting and photosynthetic performance, are characterized by net photosynthetic assimilation utilizing mainly the atmospheric carbon dioxide. In contrast, chlorophyll-containing bark and wood tissue, most fruit, root and fertile flower organs are primary sub­ ordinated to non-photosynthetic functions, but typically perform an effective internal CO2 recycling using the respiratory released CO2. Non-foliar photosynthesis, either manifested as positive net photosynthesis or internal CO2 refixation is regarded as an important strategy of additional carbon acquisition. The main strategies of additional carbon acquisition by non-foliar chlorophyllous organs are illustrated, presenting selected examples developed in reproductive as well as in vegetative plant structures.

We present here a survey of ca. 100 species within 16 genera of the family Ranunculaceae for the presence of ecdysteroid agonist and antagonist activities in methanolic seed extracts. The levels of phytoecdysteroids (agonists) have been quantified by radioimmunoassay and bioassay. A few samples possess weak antagonistic activity. Phytoecdysteroids are most prominently associated with the genus Helleborus. In this genus, species fall into two distinct classes: those with low or undetectable ecdysteroid levels and those with high ecdysteroid levels. The relationship between ecdysteroid levels and the biology of the plants in this genus is discussed. Additionally, the extract of Hepatica triloba Chaix seeds contains a significant level of phytoecdysteroids. Several other species contain low levels of phytoecdysteroids, as detected by radioimmunoassay. Together with our previous data on the genera Anemone and Pulsatilla, this survey allows us to present an overview of the distribution of ecdysteroids in this family. [Copyright &y& Elsevier]

Genome size (C-values) and pollen viability staining were applied as new criteria to investigate the species of the genus Helleborus Linnaeus (Ranunculaceae). All species have the same chromosome number (2n=32). However, the nuclear DNA content, as measured by flow cytometry with propidium iodide, could be demonstrated to range between 19 pg to 35.7 pg. The different genome sizes of the species coincided to a large extent with earlier determined section boundaries based on morphology. Flow cytometry can be a convenient method to discriminate between some species. [ABSTRACT FROM AUTHOR]