Die Alloiophyllie der Anemone nemorosa und ihre vermutliche Ursache

Ohne Zusammenfassung     

Gytological studies of Anemone nemorosa L. (Ranunculaceae)

Investigations of mitosis in 10 populations of Anemone nemorosa L. all indicated that this species has a chromosome number of 2 n = 30. No B chromosomes were found. There were no significant differences in chromosome morphology between the populations. Meiosis in the anthers, studied in three populations, was found to be mostly regular, with 15 bivalents, although occasional irregularities such as bridges and pentads were observed. Pollen viability was tested in 12 populations and although fairly low, with micro pollen grains in four of the populations, was not low enough to prevent a high proportion of fertilized achenes.     

Rhizome Growth and Clone Development in Anemone nemorosa L.

Studies of natural populations indicate that clones grow radially,soon developing a hollow centre which may be invaded by newgenotypes. In the populations studied, individual rhizomes elongate byan average of 2.5 cm per year. Growth is sympodial, the terminalbud forming an aerial shoot and further elongation occurringfrom an axillary bud. The oldest rhizome segment found was 7 years with most rhizomesbeing 3 or 4 years old. Because there is no apparent senescence,individual clones may persist for very long periods, possiblyhundreds of years. A computer model of rhizome growth was used to postulate theextent of intermixing of old clones. It indicated that old clonesbecome very fragmentary and totally inmixed with their neighbours,one ‘clump’ often representing several clones. To supplement the model, plants from a woodland with an unbrokencarpet of Anemone nemorosa were collected, 27 morphologicalcharacters measured and the data analysed using principal componentsanalysis and cluster analysis. These supported the hypothesisthat old clones are large and fragmentary with complete intermixing. The possible role of soil factors in influencing rhizome extensionis discussed and the strategy of A.nemorosa is compared withthose of its close associates in the pre-vernal woodland herblayer. Anemone nemorosa L., wood anemone, rhizome growth, clone development, computer model, vegetative reproduction     

Interactions between two rust fungi and their host plant Anemone nemorosa

In a field study we found that two rust fungi. Tranzchelia anemones and Ochropsora ariae. on the shared host Anemone nemorosa varied in abundance among populations. Tranzchelia anemones was favoured in high light habitats and was particularly common in mixed deciduous forests as well as productive grasslands, whereas the abundance and occurrence of O. ariae was dependent on the presence of the alternate host, Sorbus aucuparia When found in the same population, the two rusts rarely attacked the same ramet. Both T. anemones and O. ariae had a negative effect on plant performance by reducing flower production, and rhizome length. Diseased shoots were also elongated.     

A latitudinal gradient in seed nutrients of the forest herb Anemone nemorosa

The nutrient concentration in seeds determines many aspects of potential success of the sexual reproductive phase of plants, including the seed predation probability, efficiency of seed dispersal and seedling performance. Despite considerable research interest in latitudinal gradients of foliar nutrients, a similar gradient for seeds remains unexplored. We investigated a potential latitudinal gradient in seed nutrient concentrations within the widespread European understorey forest herb Anemone nemorosa L. We sampled seeds of A. nemorosa in 15 populations along a 1900-km long latitudinal gradient at three to seven seed collection dates post-anthesis and investigated the relative effects of growing degree-hours >5 °C, soil characteristics and latitude on seed nutrient concentrations. Seed nitrogen, nitrogen:phosphorus ratio and calcium concentration decreased towards northern latitudes, while carbon:nitrogen ratios increased. When taking differences in growing degree-hours and measured soil characteristics into account and only considering the most mature seeds, the latitudinal decline remained particularly significant for seed nitrogen concentration. We argue that the decline in seed nitrogen concentration can be attributed to northward decreasing seed provisioning due to lower soil nitrogen availability or greater investment in clonal reproduction. This pattern may have large implications for the reproductive performance of this forest herb as the degree of seed provisioning ultimately co-determines seedling survival and reproductive success.     

Atmospheric nitrogen deposition on petals enhances seed quality of the forest herb Anemone nemorosa

• Elevated atmospheric input of nitrogen (N) is currently affecting plant biodiversity and ecosystem functioning. The growth and survival of numerous plant species is known to respond strongly to N fertilisation. Yet, few studies have assessed the effects of N deposition on seed quality and reproductive performance, which is an important life‐history stage of plants.
• Here we address this knowledge gap by assessing the effects of atmospheric N deposition on seed quality of the ancient forest herb Anemone nemorosa using two complementary approaches.
• By taking advantage of the wide spatiotemporal variation in N deposition rates in pan‐European temperate and boreal forests over 2 years, we detected positive effects of N deposition on the N concentration (percentage N per unit seed mass, increased from 2.8% to 4.1%) and N content (total N mass per seed more than doubled) of A. nemorosa seeds. In a complementary experiment, we applied ammonium nitrate to aboveground plant tissues and the soil surface to determine whether dissolved N sources in precipitation could be incorporated into seeds. Although the addition of N to leaves and the soil surface had no effect, a concentrated N solution applied to petals during anthesis resulted in increased seed mass, seed N concentration and N content.
• Our results demonstrate that N deposition on the petals enhances bioaccumulation of N in the seeds of A. nemorosa. Enhanced atmospheric inputs of N can thus not only affect growth and population dynamics via root or canopy uptake, but can also influence seed quality and reproduction via intake through the inflorescences.

     

Estimation of the relative importance of sexual and vegetative reproduction in the clonal woodland herb Anemone nemorosa

Anemone nemorosa is a perennial rhizomatous plant of European woodlands. The “probability of clonal identity” method estimated the relative proportion of sexual to vegetative reproduction in this species to be 4.4% from allozyme genotype distributions. This result is congruent with investigations on the germination, short-term demography, population genetics, and breeding system of this species, and supports the hypothesis that even low levels of seedling recruitment can maintain considerable intrapopulational genetic diversity. Received: 2 March 1998 / Accepted: 24 July 1998     

Nectar production in the pollen flower of Anemone nemorosa in comparison with other Ranunculaceae and Magnolia (Magnoliaceae)

The observation that the flowers of Anemone nemorosa offer nectar to pollinating bee-flies (Bombylius major) prompted this investigation into the site of nectar secretion and nectary tissue. To allow comparison on a broader basis, other nectar-secreting pollen flowers of the Ranunculaceae and Magnolia (Magnoliaceae) were included in the analysis. The contradictory information available on the function of the mouthparts of bee-flies during nectar and pollen feeding motivated us to investigate the proboscis structure in detail by SEM. Our investigations in Anemone nemorosa proved, for the first time, nectar secretion in the genus Anemone s.s. (i.e. other than the Pulsatilla group) and in addition, within the family, a new type of a carpellary nectary. The latter is an epithelial nectary involving the whole epidermis of the ovarian part of the carpel. The nectary of Anemone nemorosa resembles that of Magnolia (e.g. M. stellata), which we re-investigated. In both Anemone nemorosa and Magnolia stellata, nectar production is limited mainly to the female phase of the proterogynous flower. In this way, the attractiveness of the flower is also assured in the non-pollen presenting phase. Especially in Magnolia, with its numerous carpels arranged on a cone-like receptacle, the economic disadvantage of a choricarpous- compared to a coenocarpous-gynoecium is compensated for by nectar secretion by each carpel. When licking up the nectar droplets from the carpel surfaces, contact of the insect's body with each stigma may be achieved.     

Le comportement parasitaire de Sclerotinia tuberosa (hedw.) Fuckel sur Anemone nemorosa L. Etude en microscopie photonique et electronique a balayage

Résumé Des rhizomes d'Anemone nemorosa infectés par Sclerotinia tuberosa ont été trouvés dans le sol. Ils ont été étudiés macroscopiquement, en microscopie photonique et en microscopie électronique à balayage. Des infections artificielles ont été réalisées in vitro. Un manchon mycélien entoure le rhizome, et des coussinets d'infection se forment au contact de la cuticule où ils émettent des filaments d'infection qui traversent les couches cuticulaires successivement sécrétées par l'hôte. La colonisation des tissus du rhizome se fait par voie intracellulaire, des appressoria simples servant à franchir les parois cellulaires, mais aussi par voie intercellulaire si l'infection débute au niveau d'une blessure du rhizome. Les mécanismes observés sont en accord avec les préférences nutritionnelles du champignon en culture pure.

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Rhizomes of Anemone nemorosa infected by Sclerotinia tuberosa have been found in soil. They have been studied macroscopically and by means of light and scanning electron microscopy. In addition artificial infections have been produced in vitro. Fungal hyphae coat the rhizome with a mycelial muff. Infection cushions develop near the cuticle, and they produce infection threads which penetrate through it. The colonization of the host plant tissues goes on either by intracellularly — the hyphae then go from cell to cell, perforating the cell walls by mean of simple appressoria — or by intercellularly — especially when the infection is initiated by a wound in the rhizome. The infection mechanisms observed here fit well with the nutritional requirements of the fungus in pure culture.

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Avec la collaboration technique de D. Bernillon     

Tree litter and forest understorey vegetation: a conceptual framework to understand the effects of tree litter on a perennial geophyte, Anemone nemorosa

Background and Aims

Litter is a key factor in structuring plant populations, through positive or negative interactions. The litter layer forms a mechanical barrier that is often strongly selective against individuals lacking hypocotyle plasticity. Litter composition also interacts with plant growth by providing beneficial nutrients or, inversely, by allowing harmful allelopathic leaching. As conspicuous litter fall accumulation is often observed under deciduous forests, interactions between tree litter and understorey plant populations are worthy of study.

Methods

In a 1-year ex-situ experiment, the effects of tree litter on the growth of Anemone nemorosa, a small perennial forest geophyte, were investigated. Three ‘litter quantity’ treatments were defined, representative of forest floor litter (199, 356·5 and 514 g m⁻²), which were crossed with five ‘litter composition’ treatments (Quercus petraea, Fagus sylvatica, Carpinus betulus, Q. petraea + F. sylvatica and Q. petraea + C. betulus), plus a no-litter control. Path analysis was then used to investigate the pathways linking litter characteristics and components of adult plant growth.

Key Results

As expected, the heavier the litter, the longer the petiole; rhizome growth, however, was not depreciated by the litter-induced petiole lengthening. Both rhizome mass increment and number of initiated buds marginally increased with the amount of litter. Rhizome mass increment was in fact determined primarily by leaf area and leaf life span, neither of which was unequivocally correlated with any litter characteristics. However, the presence of litter significantly increased leafing success: following a late frost event, control rhizomes growing in the absence of litter experienced higher leaf mortality before leaf unfolding.

Conclusions

The study questions the role of litter as a physical or chemical barrier to ground vegetation; to better understand this role, there is a need for ex-situ, longer-term experiments coupled with in-situ observations in the forest.     

The influence of local elevation on soil properties and tree health in remnant eucalypt woodlands affected by secondary salinity

More than 2 M ha of remnant vegetation in Australia is predicted to be at risk from shallow water tables by 2050. Currently, vegetation is considered to be at risk where the water table is predicted to be less than 2 m below the soil surface, yet casual observation of areas affected by secondary salinity in the Western Australian wheatbelt has suggested that small differences in elevation (< 0.5 m) are important in determining plant health. In this study, we investigated how small changes in elevation (and hence depth to the water table) affected soil Cl concentrations and water contents, and whether small changes in elevation were associated with major changes in tree health in two remnants of Eucalyptus wandoo Blakely woodland with secondary salinity. At one site there were strong dissimilarities between soil samples collected above or below relative elevations of 0.5 m in areas with a shallow (0.3 m deep in September 2001) and saline water table. This was reflected in almost complete tree mortality at relative elevations below 0.5 m. However, low rainfall in 2001 meant that it was unlikely that current soil conditions had caused tree death. When water table data for 1999 was overlaid over plots of tree health and transect topography, high levels of tree mortality corresponded with areas where the water table was at or above the ground surface. At the other site, there was no clear relationship between elevation, soil characteristics and tree health. Localised variation in abiotic conditions and ecosystem processes at a fine-scale may buffer, to some extent, the spatial impact of soil salinity and waterlogging in remnant vegetation. Collapses in tree health at some sites are likely to be related to extreme and episodic events, which we may have limited ability to predict.     

Characterization of Colletotrichum acutatum Causing Anthracnose of Anemone (Anemone coronaria L.)

Anthracnose, or leaf-curl disease of anemone, caused by Colletotrichum sp., has been reported to occur in Australia, western Europe, and Japan. Symptoms include tissue necrosis, corm rot, leaf crinkles, and characteristic spiral twisting of floral peduncles. Three epidemics of the disease have been recorded in Israel: in 1978, in 1990 to 1993, and in 1996 to 1998. We characterized 92 Colletotrichum isolates associated with anthracnose of anemone (Anemone coronaria L.) for vegetative compatibility (72 isolates) and for molecular genotype (92 isolates) and virulence (4 isolates). Eighty-six of the isolates represented the three epidemics in Israel, one isolate was from Australia, and five isolates originated from western Europe. We divided these isolates into three vegetative-compatibility groups (VCGs). One VCG (ANE-A) included all 10 isolates from the first and second epidemics, and 13 of 62 examined isolates from the third epidemic in Israel, along with the isolate from Australia and 4 of 5 isolates from Europe. Another VCG (ANE-F) included most of the examined isolates (49 of the 62) from the third epidemic, as well as Colletotrichum acutatum from strawberry, in Israel. Based on PCR amplification with species-specific primers, all of the anemone isolates were identified as C. acutatum. Anemone and strawberry isolates of the two VCGs were genotypically similar and indistinguishable when compared by arbitrarily primed PCR of genomic DNA. Only isolate NL-12 from The Netherlands, confirmed as C. acutatum but not compatible with either VCG, had a distinct genotype; this isolate represents a third VCG of C. acutatum. Isolates from anemone and strawberry could infect both plant species in artificial inoculations. VCG ANE-F was recovered from natural infections of both anemone and strawberry, but VCG ANE-A was recovered only from anemone. This study of C. acutatum from anemone illustrates the potential of VCG analysis to reveal distinct subspecific groups within a pathogen population which appears to be genotypically homogeneous by molecular assays.     

Colonization of new habitats by earthworms

Summary In this paper a simple model is used to study the dispersal of earthworm populations into new habitats. Simple models do not describe processes accurately, but can help gain insight into the functioning of ecosystems or processes in ecosystems. Using information on reproduction, survival and dispersal at the level of the individual, the velocity of earthworm population expansion was calculated. Dispersal of earthworms can be active or passive. The parameters of active and passive dispersal were calculated from field experiments in one of the Dutch polders. Parameters of reproduction and survival were estimated from published data. The effects of processes at the individual level on the velocity of population expansion were studied for two species (Aporrectodea caliginosa and Lumbricus rubellus). The model shows that passive transport has a major influence on the velocity of population expansion, which is strongly increased even if this transport involves only a very small part of the population. At a high level of passive transport, however, death induced by this mode of dispersal can have a negative influence on population expansion. In the discussion it is indicated that optimising growth conditions of the earthworms might be the easiest way to promote population expansion. However, promoting dispersal by passive mechanisms can also be very important.Communication no. 36 of the Dutch Programme on Soil Ecology of Arable Farming Systems     

九节菖蒲脂溶性成分GC-MS分析

本文采用索氏提取法提取九节菖蒲中脂溶性成分,进行甲酯化处理后,利用气相色谱-质谱联用技术对其组成和含量进行定性定量分析,共鉴定出21种脂溶性成分,主要为亚麻酸、亚油酸、棕榈酸和芥酸,相对含量分别为48．26％、29．23％、10．63％和2．13％。九节菖蒲脂溶性成分具有较高的营养保健价值,值得进一步开发利用。     

HPLC法测定九节菖蒲中琥珀酸含量

目的:建立九节菖蒲中琥珀酸含量的HPLC测定法。方法:采用Kromasil C18色谱柱(150 mm×4.6 mm,5μm);甲醇-0.02mol/L KH2PO4缓冲液(7:93)(pH 2.5)为流动相;流速0.5 mL/min;柱温为30℃;检测波长为214 nm。结果:琥珀酸在4～48μg范围内具有良好的线性关系,平均加样回收率为99.15%。九节菖蒲样品中的琥珀酸含量,以干燥品计为0.200%～0.318%。结论:该方法可行,重复性好,可用于九节菖蒲中琥珀酸含量的测定。