Perennial Rhizome Research Articles

Responses of plant diversity and primary productivity to nutrient addition in a Stipa baicalensis grassland, China

Nutrient addition can affect the structure and diversity of grassland plant communities, thus alter the grassland productivity. Studies on grassland plant community composition, structure and diversity in response to nutrient addition have an important theoretical and practical significance for the scientific management of grassland, protection of plant diversity and the recovery of degraded grassland. A randomized block design experiment was conducted with six blocks of eight treatments each: control (no nutrient addition) and K, P, N, PK, NK, NP, and NPK addition. We evaluated plant composition, height, coverage, density, and aboveground biomass to estimate primary productivity and plant diversity. Results showed that all treatments increased primary productivity significantly (P<0.05) with the exception of the K and the NPK treatments had the greatest effect, increasing aboveground biomass 2.46 times compared with the control (P<0.05). One-way ANOVA and factorial analysis were used for the species richness, Shannon-Wiener index, Pielou index and aboveground biomass, and the relationships between the diversity indices and aboveground biomass were determined through linear regression. We found that fertilization altered the community structure; N (but not P or K) addition increased the proportion of perennial rhizome grasses and significantly reduced that of perennial forbs (P<0.05), thus it presented a trend of decrease in species richness, Shannon-Wiener and Pielou indexex, respectively. Only the main effects of N had significant impacts on both the diversity indices and the aboveground biomass (P<0.05), and the interactions between N-P, N-K, P-K and N-P-K could be neglected. With fertilization, plant diversity (correlation coefficient, −0.61), species richness (−0.49), and species evenness (–0.51) were all negatively linearly correlated with primary productivity. The correlations were all significant (P<0.01). Scientific nutrient management is an effective way to improve grassland productivity, protect the plant diversity as well as recover the degraded grassland.

Biotic community shifts explain the contrasting responses of microbial and root respiration to experimental soil acidification

Soil respiration is comprised primarily of root and microbial respiration, and accounts for nearly half of the total CO2 efflux from terrestrial ecosystems. Soil acidification resulting from acid deposition significantly affects soil respiration. Yet, the mechanisms that underlie the effects of acidification on soil respiration and its two components remain unclear. We collected data on sources of soil CO2 efflux (microbial and root respiration), above- and belowground biotic communities, and soil properties in a 4-year field experiment with seven levels of acid in a semi-arid Inner Mongolian grassland. Here, we show that soil acidification has contrasting effects on root and microbial respiration in a typical steppe grassland. Soil acidification increases root respiration mainly by an increase in root biomass and a shift to plant species with greater specific root respiration rates. The shift of plant community from perennial bunchgrasses to perennial rhizome grasses was in turn regulated by the decreases in soil base cations and N status. In contrast, soil acidification suppresses microbial respiration by reducing total microbial biomass and enzymatic activities, which appear to result from increases in soil H+ ions and decreases in soil base cations. Our results suggest that shifts in both plant and microbial communities dominate the responses of soil respiration and its components to soil acidification. These results also indicate that carbon cycling models concerned with future climate change should consider soil acidification as well as shifts in biotic communities.

Effects of nitrogen enrichment on belowground communities in grassland: Relative role of soil nitrogen availability vs. soil acidification

Terrestrial ecosystems worldwide are receiving increasing amounts of biologically reactive nitrogen (N) as a consequence of anthropogenic activities. This intended or unintended fertilization can have a wide range of impacts on the above- and belowground communities. An increase in high N availability has been assumed to be a major mechanism enhancing the abundance of above- and belowground communities. In addition to increasing available N, however, N enrichment causes soil acidification, which may negatively affect above- and belowground communities. The relative importance of increased N availability vs. increased soil acidity for above- and belowground communities in natural ecosystems experiencing N enrichment is unclear. In a 12-year N enrichment experiment in a semi-arid grassland, N enrichment substantially increased both above- and belowground plant biomass mainly via the N availability-induced increase in biomass of perennial rhizome grasses. N enrichment also dramatically suppressed bacterial, fungal, and actinobacteria biomass mainly via the soil acidification pathway (acidification increased concentrations of H+ ions and Al3+ and decreased concentrations of mineral cations). In addition, N enrichment also suppressed bacterial-, fungal-feeding, and omnivorous + carnivorous nematodes mainly via the soil acidification pathway (acidification reduced nematode food resources and reduced concentrations of mineral cations). The positive effects resulting from the increase in belowground carbon allocation (via increase in quantity and quality of plant production) on belowground communities were outweighed by the negative effects resulting from soil acidification, indicating that N enrichment weakens the linkages between aboveground and belowground components of grassland ecosystems. Our results suggest that N enrichment-induced soil acidification should be included in models that predict biota communities and linkages to carbon and nitrogen cycling in terrestrial ecosystems under future scenarios of N deposition.

Discovery and analysis of microRNAs in Leymus chinensis under saline-alkali and drought stress using high-throughput sequencing.

Leymus chinensis (Trin.) Tzvel. is a perennial rhizome grass of the Poaceae (also called Gramineae) family, which adapts well to drought, saline and alkaline conditions. However, little is known about the stress tolerance of L. chinensis at the molecular level. microRNAs (miRNAs) are known to play critical roles in nutrient homeostasis, developmental processes, pathogen responses, and abiotic stress in plants. In this study, we used Solexa sequencing technology to generate high-quality small RNA data from three L. chinensis groups: a control group, a saline-alkaline stress group (100 mM NaCl and 200 mM NaHCO3), and a drought stress group (20% polyethylene glycol 2000). From these data we identified 132 known miRNAs and 16 novel miRNAs candidates. For these miRNAs we also identified target genes that encode a broad range of proteins that may be correlated with abiotic stress regulation. This is the first study to demonstrate differentially expressed miRNAs in L. chinensis under saline-alkali and drought stress. These findings may help explain the saline-alkaline and drought stress responses in L. chinensis.

Relationship of ecosystem primary productivity to species diversity and functional group diversity: evidence from Stipa breviflora grassland in Nei Mongol

Aims The relationship between biodiversity and ecosystem functioning has been a central issue in ecology. However, this relationship is poorly understood for the Stipa breviflora grassland, which is a major community type of desert steppe in Nei Mongol. With unpredictably fluctuating climate conditions, these desert steppe ecosystems are fragile and provide a unique opportunity to test our current understanding of the relationship between biodiversity and ecosystem functioning. This study has two objectives: (1) to examine if species diversity and functional group diversity affect ecosystem primary productivity in the desert steppe of Nei Mongol and (2) to explore how resource supply levels affect the relationship between diversity and productivity. Methods Based on life forms, species were classified into five functional groups: shrub and semishrub, perennial bunchgrass, perennial rhizome grass, perennial forb, and annual and biennial. Species richness and functional group richness were used to represent species diversity and functional group diversity, respectively. Based on the dryness coefficient, 202 sites across the S. breviflora grassland in Nei Mongol were sampled, and divided into two resource supply levels: arid and semiarid zones. In order to tease out the effect of precipitation, partial regression analysis and partial correlation analysis were used for exploring the relationship of ecosystem primary productivity to species richness and functional group richness, respectively. According to the determination coefficient of regression analysis, the effect of resource supply levels on the diversity-productivity relationship was evaluated.Important findings Species richness and ecosystem primary productivity were both positively and linearly correlated with precipitation, but no significant correlation was found between functional group richness and precipitation. Ecosystem primary productivity increased significantly with species richness, but not with functional group richness. Resource supply levels could affect the diversity-productivity relationship in that plant species diversity generally had a weaker effect on ecosystem primary productivity at the lower resource supply level and a stronger effect at the higher resource supply level.

松嫩草地66种草本植物叶片性状特征

植物叶片功能性状及其相互关系越来越受到关注。以松嫩草地66种草本植物为研究对象,测量叶片干物质含量、比叶面积、叶片厚度、叶片氮含量、叶片磷含量、叶绿素含量和类胡萝卜素含量,检验性状间的相互关系,比较不同功能群(多年生根茎禾草,多年生丛生禾草,多年生杂类草,1年生或2年生草本)间性状的差异性。结果表明,叶片厚度变异系数最大,比叶面积、叶片氮含量、叶片磷含量、叶绿素含量和类胡萝卜素含量之间存在显著的正相关关系;叶片干物质含量与叶片磷含量没有显著的相关关系,与其它叶片性状呈显著的负相关关系;叶片厚度只与叶片干物质含量和比叶面积呈显著的负相关关系,与其它叶片性状不相关。叶片干物质含量、比叶面积、叶片厚度、叶片氮、磷含量在4个功能群间差异显著,叶绿素含量和类胡萝卜素含量在各个功能群间差异不显著;多年生根茎禾草和多年生丛生禾草叶片的7个性状差异不显著;多年生根茎禾草和多年生丛生禾草的叶片干物质含量高于多年生杂类草和1年生或2年生草本,其它性状小于这两个功能群。;Leaf traits such as specific leaf area (SLA) and leaf nitrogen concentration (LNC) play important roles in plant functioning and are affected strongly by ecosystem properties and local environmental conditions. Quantifying the relationships between leaf traits and traits differences among plant functional groups has received increasing attentions in plant functional ecology over the past two decades.<br>We measured in total 7 leaf traits: SLA, LNC, leaf dry matter content (LDMC), leaf thickness (LT), leaf phosphorus concentration (LPC), leaf chlorophyll (a+b) content (Chl) and leaf carotenoid content (Cd) among 66 herbaceous species. And we analyzed the correlation between leaf traits and the traits difference among perennial rhizome grass (PR), perennial bunchgrasses (PB), perennial forbs (PF) and annuals/biannuals (AB) in Songnen grassland, Northeast China.<br>The results showed that LT variation (59.1%) was the highest among the 7 leaf traits measured. Pearson correlation showed that SLA, LNC, LPC, Chl and Cd were positively correlated with each other significantly. There was no significant correlation between LDMC and LPC, however, LDMC was negatively correlated with all other leaf traits significantly. LT was only negatively correlated to LDMC and SLA significantly, but not with others. LDMC, SLA, LT, LNC, LPC were significantly different among the 4 plant functional groups analyzed by one-way ANOVA (<em>P</em><0.05). There was no difference between Chl and Cd. PR and PB had no difference among the 7 leaf traits. The LDMC of PR and PB were significantly higher than PF and AB. SLA, LNC, LPC of PR and PB were lower than PF and AB.

Altitudinal changes in the growth and allometry of Rumex alpinus

Alpine plants growing along altitudinal gradients have been traditionally considered to have reduced flowering and growth and enhanced clonality toward higher altitudes. This pattern, however, has seldom been studied for multiple characteristics in one plant species and over several years, and thus its generality is uncertain. In the present study, we used annual growth markers on perennial rhizomes (herbchronology) to analyze the long-term growth of Rumex alpinus. By determining the width and length of rhizome segments (annual increments) and the numbers of leaf scars, inflorescence scars, dormant buds, and branches preserved on rhizomes, we analyzed past growth for more than 10 years at seven sites along an altitudinal gradient (950–1,900 m a.s.l.) in the Low Tatra Mts., West Carpathians, Slovakia. We determined where growth was optimum on the gradient and whether the data supported the common opinion that clonal growth is enhanced and flowering is reduced with increasing altitude. Although R. alpinus is a light-demanding species occurring preferentially along small streams above the treeline, the most vigorous growth (highest number of leaves and inflorescences) occurred at low altitudes in forest clearings. According to expectation, R. alpinus exhibited less flowering and growth but increased clonality with increasing altitude. Low temporal inequality in growth indicates that the perennial rhizome system plays a role in buffering year to year climatic variability in the harsh environment along altitudinal gradients.

Impact of nitrogen addition on plant community in a semi-arid temperate steppe in China

Increased nitrogen (N) deposition will often lead to a decline in species richness in grassland ecosystems but the shifts in functional groups and plant traits are still poorly understood in China. A field experiment was conducted at Duolun, Inner Mongolia, China, to investigate the effects of N addition on a temperate steppe ecosystem. Six N levels (0, 3, 6, 12, 24, and 48 g N/(m⋅a)) were added as three applications per year from 2005 to 2010. Enhanced N deposition, even as little as 3 g N/(m⋅a) above ambient N deposition (1.2 g N/(m⋅a)), led to a decline in species richness of the whole community. Increasing N addition can significantly stimulate aboveground biomass of perennial bunchgrasses (PB) but decrease perennial forbs (PF), and induce a slight change in the biomass of shrubs and semi-shrubs (SS). The biomass of annuals (AS) and perennial rhizome grasses (PR) accounts for only a small part of the total biomass. Species richness of PF decreased significantly with increasing N addition rate but there was a little change in the other functional groups. PB, as the dominant functional group, has a relatively higher height than others. Differences in the response of each functional group to N addition have site-specific and species-specific characteristics. We initially infer that N enrichment stimulated the growth of PB, which further suppressed the growth of other functional groups.

Plant functional type effects on methane uptake by soils in typical grasslands of Inner Mongolia

Aims Methane (CH4) is an important atmospheric trace gas contributing to global warming and atmospheric chemistry. Aerated soils are a biological sink for atmospheric CH4. Our objectives were to quantify CH4 uptake by soils in typical grasslands of Inner Mongolia and examine the effects of plant functional type on the uptake. Methods We used static chamber sampling and gas chromatography measurement to examine the effects of four plant functional types (PFTs) ― perennial rhizome forbs (PR), perennial bunchgrass (PB), perennial forb (PF) and annuals and biennials (AB) ― on CH4 uptake by aerated soils. Important findings CH4 uptake by soils showed seasonal change related to soil water content and temperature. Over most of observed periods in 2008 and 2009, there were no significant differences in soil CH4 uptake rates among the various PFTs. During rapid plant growth in August, however, there were significant differences in the soil CH4 uptake rates. The soil CH4 uptake rates were lower with PBs. AB and PF increased the uptake of CH4 by soils, while PR and PB had little influence. Soil physico-chemical factors such as temperature, water content and gas diffusion affect CH4 uptake. Differences in CH4 uptake rates by soils may be explained using these environmental factors affected by PFTs. With regard to trace gas, PFT has prominent effects on this ecosystem. Sub-dominant species and companion species (AB and PF), by regulating soil microbe and environmental factors, have important and irreplaceable roles on the uptake of CH4 by soils.

Responses of photosynthetic capacity to soil moisture gradient in perennial rhizome grass and perennial bunchgrass.

BackgroundChanging water condition represents a dramatic impact on global terrestrial ecosystem productivity, mainly by limiting plant functions, including growth and photosynthesis, particularly in arid and semiarid areas. However, responses of the potential photosynthetic capacity to soil water status in a wide range of soil moisture levels, and determination of their thresholds are poorly understood. This study examined the response patterns of plant photosynthetic capacity and their thresholds to a soil moisture gradient in a perennial rhizome grass, Leymus chinensis, and a perennial bunchgrass, Stipa grandis, both dominant in the Eurasian Steppe.ResultsSevere water deficit produced negative effects on light-saturated net CO2 assimilation rate (Asat), stomatal conductance (gs), mesophyll conductance (gm), maximum carboxylation velocity (Vc,max), and maximal efficiency of PSII photochemistry (Fv/Fm). Photosynthetic activity was enhanced under moderate soil moisture with reductions under both severe water deficit and excessive water conditions, which may represent the response patterns of plant growth and photosynthetic capacity to the soil water gradient. Our results also showed that S. grandis had lower productivity and photosynthetic potentials under moderate water status, although it demonstrated generally similar relationship patterns between photosynthetic potentials and water status relative to L. chinensis.ConclusionsThe experiments tested and confirmed the hypothesis that responsive threshold points appear when plants are exposed to a broad water status range, with different responses between the two key species. It is suggested that vegetation structure and function may be shifted when a turning point of soil moisture occurs, which translates to terms of future climatic change prediction in semiarid grasslands.

Carbohydrate composition in delayed harvested reed canary grass

Abstract Reed canary grass (Phalaris arundinacea L.) samples of the Palaton variety grown at 10 different locations in northern Europe were analyzed and the effect of growing location and soil type on the carbohydrate composition and lignin content were investigated. The results showed that the major carbohydrate components in delayed harvested reed canary grass were glucose and xylose. Some growing locations and soil types significantly influenced the carbohydrate composition of the grass. Soils with both high organic and clay content produced lower glucose and xylose contents but an increased lignin content. A soil rich in sand gave higher glucose, xylose and arabinose content. Reed canary grass is a perennial rhizome grass that has shown potential as an energy crop for solid bio-fuel production and as a short fibre raw material for the pulp and paper industry. This study showed that delayed harvested reed canary grass can also be a potential new raw material for ethanol production.

Development of ginger based ready-to-eat appetizers by response surface methodology

Ginger is an herbaceous perennial rhizome traditionally used in culinary for its flavor and pungency. It is also used as carminative, stimulant and for its anti-emetic properties due to gingerols and shogaols. Appetite loss is one of the problems faced at high altitudes and the appetizers based on ginger may be useful for appetite stimulation. The fruit munch and ginger munch based on fresh and powdered ginger respectively were developed using response surface methodology (RSM). The sensory score, acidity and total sugars were the responses in the central composite designs of experiments with three independent variables. The ingredients raisins, dates, almonds were pre-processed by frying in stable fat while juice was extracted from pseudolemon and lemon. The optimized composition of ingredients was processed further through concentration. The carbohydrate rich munches had vitamin C content in the range 37–43mg/100g and calorific value of about 90kCal per munch. The munches packed in metalized polyester pouches had a shelf life of 8 months at ambient conditions (18–33°C) as well as at a fixed temperature of 37°C storage.

Differential responses of plant functional trait to grazing between two contrasting dominant C3 and C4 species in a typical steppe of Inner Mongolia, China

Plant functional traits have been widely used to study the linkage between environmental drivers, trade-offs among different functions within a plant, and ecosystem structure and functioning. Here, the whole-plant traits, leaf morphological and physi- ological traits of two dominant species, Leymus chinensis (C3 perennial rhizome grass) and Cleisto- genes squarrosa (C4 perennial bunchgrass), were studied in the Inner Mongolia grassland of China, with a grazing experiment including five stocking rates (0, 3.0, 4.5, 7.5, and 9.0 sheep/ha) in 2008 (wet year) and 2009 (dry year). Our results demonstrated that, for both species, the effects of stocking rate, year, and stocking rate×year on whole-plant traits and leaf morphological and physiological traits were highly significant in most cases. The differential responses of plant trait to variation in precipitation were caused by trait trade-offs between the wet and dry years. L. chinensis adopted the high N content and net photosynthetic rate (Pn) in the wet year but both the low N content and Pn in the dry year under grazed conditions. The trait trade-offs of C. squarrosa were characterized by high specific leaf area (SLA) and Pn in the dry year vs. low SLA and Pn in the wet year. Our findings also indicate that C. squarrosa is more resistant to grazing than L. chinensis in terms of avoidance and tolerance traits, particularly under heavy grazing pressure and in the dry year.

Effects of plant growth regulators and l-glutamic acid on shoot organogenesis in the halophyte Leymus chinensis (Trin.)

The halophyte Leymus chinensis (Trin.) is a perennial rhizome grass (tribe Gramineae) that is widely distributed in China, Mongolia and Siberia, where it is produced as a forage product. In this report, we establish a highly reproducible plant regeneration system through somatic embryogenesis. Two explants, mature seeds and leaf base segments were used; these parts displayed different responses to combinations of growth factors that affect embryogenic callus induction, callus type optimization and plant regeneration. The highest callus induction frequency was obtained on Murashige and Skoog (MS) medium supplemented with 2.0 mg l−1 2,4-dichlorophenoxyacetic acid (2,4-D) in the presence of 5.0 mg l−1 l-glutamic acid. The inclusion of 5.0 mg l−1 l-glutamic acid was found to significantly promote primary callus induction, embryogenic callus formation and callus status improvement. Subculturing on maintenance medium for 1–2 months before plant regeneration was found to be essential for the optimization of callus type and the maturation of embryogenic callus. Callus relative water content and growth rate were simultaneously investigated during callus maintenance, and found to possibly be related to callus type. Shoots were differentiated from the embryogenic callus on the optimal medium with MS salts containing 0.2–0.5 mg l−1 α-naphthalene acetic acid (NAA), 2.0 mg l−1 kinetin (Kn) and 2.0 g l−1 casamino acids in 71.0 and 69.2% of wild-type (WT) and Jisheng No.1 (JS) plants, respectively. Plant regeneration was variable depending on NAA levels, and the addition of casamino acids stimulated the maturation of embryogenic callus and plant regeneration. Transferring callus with shoots onto half-strength MS medium resulted in rooting within 1 week. The growth of regenerated plants was also surveyed in the field. This is the first report of plant regeneration through somatic embryogenesis from mature seeds and leaf base segments of L. chinensis.

Somatic embryogenesis and in vitro plant regeneration from various explants of the halophyte Leymus chinensis (Trin.)

The halophyte Leymus chinensis (Trin.) is a perennial rhizome grass (tribe Gramineae) that is widely distributed throughout China, Mongolia and Siberia. This study was conducted to investigate an optimal condition for plant regeneration from mature seeds, leaf base segments, and root segments in L. chinensis. Plant growth regulators affecting embryogenic callus induction and plant regeneration were investigated by four-factor-three-level [L9 (34)] orthogonal test in this study. The effects of explants types (mature seeds, leaf base segments and root segments), callus types, medium types were examined in this study. Wild type (WT) and Jisheng No. 1 plants (JS) were used for primary callus induction. A clear explants difference was seen during callus induction; mature seeds were considered as the preferred explants; and the highest frequency of callus induction was obtained in Medium 6 using mature seeds as explants in WT. Plant regeneration ability was evaluated by frequencies of green callus forming, shooting, rooting, and shooting with roots. Effect of α-naphthalene acetic acid (NAA) on shoot regeneration was remarkable with the highest frequency of 70.8% in WT after 2-month culture. The medium with 0.2- 0.5 mg/L NAA was found to have the highest shoot induction. All regenerated shoots were successfully rooted when transferred on half-strength Murashige and Skoog (MS) basal medium. The acclimatized plantlets were grown to mature with flowering and seeds setting in green house conditions.

Comparison of light harvesting and resource allocation strategies between two rhizomatous herbaceous species inhabiting deciduous forests

Light conditions on the floor of deciduous forests are determined by the leaf dynamics of canopy trees and gap formation. Such spatiotemporal variations of light availability should affect the resource partitioning strategies of understory herbs. Although rhizomatous species are common in understory, relationships between rhizome structure, vegetative growth, and sexual reproduction are unclear in terms of carbon allocation. We compared the photosynthetic characteristics and carbon translocation patterns in the under-canopy and light-gap sites between two summer-green perennial species: Cardamine leucantha with an annual long rhizome, and Smilacina japonica with a perennial short rhizome system. Flowering of both species occurs in early summer under decreasing light availability. In the light-gap, C. leucantha maintained high photosynthetic activity due to continuous leaf production, resulting in higher seed production than in the under-canopy. In contrast, the photosynthetic rate of S. japonica, producing leaves simultaneously, decreased with time irrespective of light conditions, resulting in stable seed production in both sites. Although seasonally decreasing light availability commonly restricts carbon assimilation of understory herbs, the responses of resource partitioning to variations in light availability depend greatly on the belowground structure of individual species.

Variations in the Volatile Organic Compound Emission Potential of Plant Functional Groups in the Temperate Grassland Vegetation of Inner Mongolia, China

Abstract: The biogenic volatile organic compounds (VOC) emitted by the vegetation of a terrestrial ecosystem play a key role in both regional air quality and tropospheric chemistry. To describe the general emission properties of VOC of different plant functional groups (PFG) in a typical temperate grassland in Inner Mongolia, China, we randomly selected 175 plant species and measured the quantities of isoprene and monoterpene in situ. Results showed that most plants had low VOC emission potential at the species level, especially for some dominant plants, such as Leymus chinensis Tzvel., Stipa grandis Smirn., and Agropyron cristatum Gaertn. At the PFG level, the lowest VOC emission potential was found for perennial rhizome grasses, a major PFG in a typical temperate grassland ecosystem. The effects of overgrazing and subsequent vegetation succession on the emission of VOC by different plant life form functional groups (PLFG) were also discussed. ( Managing editor: Ya-Qin HAN)

Morphology, Growth, and Vasculature of the Sympodial Rhizome of Smilacina racemosa (Liliaceae)

A time-course study of shoot development in Smilacina racemosa was combined with an analysis of the vascular anatomy to investigate how adjacent sympodial units in the perennial rhizome are structurally related to one another. Organogenesis is seasonal and occurs over a period of 20 mo; leaves and flowers are preformed in miniature 8-12 mo before they fully expand. One lateral bud on the horizontal rhizome is initiated eccentric of the normal plane of distichy toward the lower side of the stem and develops as the renewal shoot. The vascular connection between the renewal shoot and the parent axis is complete; all but 2% of the central bundles of the parent axis directly enter or branch into the renewal shoot. Two features contribute to the completeness of the connection: (1) increased anastomoses of vascular bundles within the branch junction, and (2) the development of special girdling bundles that attach circumferentially to the parent axis. The vascular supply of dormant lateral buds is incomplete; roots attach only to the peripheral region of the central cylinder. The complete connection between adjacent sympodial units allows for a high level of physiological integration within the rhizome, while the restricted circumferential attachment of root traces may significantly influence the hydraulic pathway through the plant.

Population Biology and Mineral Nutrition of Anemone nemorosa with Emphasis on its Parasitic Fungi

Summary Fruit production, germination and plant growth were studied in a population of Anemone nemorosa , a perennial rhizome geophyte, in deciduous woods in Northern FRG. Most of the reproductive strategy is directed to vegetative reproduction, less than 5% to generative reproduction. The same tendency is present for the storage of nutrients, especially phosphorus and nitrogen, which are predominantly accumulated in the rhizome. The leaf rust fungi Ochropsora ariae and Tranzschelia anemones affect leaf performance as well as vegetative and generative reproduction. Ochropsora reduces fruit production for up to 70%, whereas Tranzschelia completely inhibit generative reproduction. The rhizome inhabiting ascomycete Sclerotinia tuberosa strongly affect the mineral nutrition and reproduction of Anemone nemorosa.

Morphology and embryology ofAsparagus virgatus Baker

This is an account of the morphology, cytoembryology, structure of fruit and seed ofAsparagus virgatus Baker, which is an exotic species seldom described in Indian floras. The plants are perennial, unarmed herbs with erect shoots and ascending cladodes. Twenty to thirty adventitious cylindrical roots arise from the underground perennial rhizome. The flowers are bisexual. The stigma is capitate. Fruit-setting is rare. The development of female gametophyte conforms to the eight-nucleatePolygonum-type. About 32% of the pollen is sterile. The haploid number of chromosomes is twenty (n=20), being recorded in this species for the first time. The same number occurs inA. tenuifolius and in a local variety ofA. racemosus. The basic number for the genus is supposed to be five, many species havingn=10 chromosomes.