Crepis Foetida Research Articles

New species of gall wasps (Hymenoptera: Cynipidae: Aulacideini and Phanacidini) inducing galls on plants of the genera Sonchus and Crepis (Asteraceae) in Romania (Dobrogea Province) and notes on their parasitoids

Two new species of herb gall wasps (Hym., Cynipidae) developing on plants in the genera Sonchus L. and Crepis L. (Asteraceae) are described from Southeastern Romania (Dobrogea Province): Aulacidea andriescui sp. n. gall inducer on Sonchus palustris L. and Phanacis dobrogicus sp. n. gall maker on Crepis foetida subsp. rhoeadifolia (M. Bieb.) Čelak. In addition to the diagnosis, identification, morphological description, life-cycle, geographical distribution, photos of gall and host plant, and SEM images, data on the associated fauna obtained from the galls of the two new species are also presented.

On the typification of the Linnaean name Crepis foetida (Asteraceae)

AbstractThe Linnaean name Crepis foetida is lectotypified with an illustration from the third volume of Morison's Plantarum historiae universalis Oxoniensis. While the designated lectotype can be identified with C. foetida s.l., it cannot be ascribed with certainty to any of the currently accepted subspecies of this taxon and is therefore considered demonstrably ambiguous.

Multiplex PCR for Discriminating Host Plant Associations of Hyalesthes obsoletus (Hemiptera: Cixiidae), a Key Vector and Driver of ‘Ca. Phytoplasma solani’ Epidemiology

Given the ecological and epidemiological specialization of Hyalesthes obsoletus, the principle vector of ‘Candidatus Phytoplasma solani’, the primary objective of this study was to develop molecular tools for discriminating three host plant associations of the vector populations: (i) Convolvulus arvensis–Urtica dioica (Ca–Ud), (ii) Vitex agnus-castus (Vac), and (iii) Crepis foetida (Cf). The genetic diversity of the nearly full-length mitochondrial COI gene (1467 bp) was analyzed and compared among previously reported and newly collected individuals of the three host plant associations on a wide geographic range. Multiplex PCR was designed and evaluated for discriminating H. obsoletus host plant associations based on the size of amplified fragments: 1084 bp for the Cf association, 645 bp for the Ca–Ud association, and 355 bp for the Vac association. Examples of the epidemiological value of combining data on the genetic characteristics of the vector and the pathogen are provided. The method is intended to facilitate an accurate identification of the vector’s phylogenetic lineage, natural host plant preference, and epidemiological transmission routes of ‘Ca. P. solani’. When applied to H. obsoletus specimens collected from cultivated plants within an agroecosystem and combined with ‘Ca. P. solani’ genotyping, the method should provide valuable information on disease epidemiology, source(s) of emergence, and transmission routes.

First report of Crepis phyllody disease associated with phytoplasma in Crepis foetida in walnut orchard in Turkey

First report of Crepis phyllody disease associated with phytoplasma in Crepis foetida in walnut orchard in Turkey

Epidemiological Role of Dictyophara europaea (Hemiptera: Dictyopharidae) in the Transmission of ‘Candidatus Phytoplasma solani’

Bois noir, an economically important disease of grapevine yellows that causes significant economic losses in wine production, is associated with ‘Candidatus Phytoplasma solani’ and transmitted to grapevines by cixiids Hyalesthes obsoletus and Reptalus panzeri. Polyphagous planthopper Dictyophara europaea, commonly found in natural habitats, harbors phytoplasmas from distinct groups and is an alternative vector in the open epidemiological cycles of the Flavescence dorée phytoplasma in grapevine in European vineyards. This study addresses the role of D. europaea in the transmission cycle(s) of ‘Ca. P. solani’ among wild habitats, natural reservoir plants, and the vineyard agroecosystem using MLSA and transmission trials with naturally infected adults to grapevine and Catharanthus roseus. The infection rates of D. europaea ranged from 7% to 13% in diverse locations, while reservoir herbaceous plants were infected in the amount of 29%. A total of 13 CaPsol MLSA genotypes were detected in D. europaea (7) and plants (8). Nine of them corresponded to previously identified genotypes. Two new genotypes were found in D. europaea (tuf-b1/S1/V14/Rqg50-sv1 and tuf-b1/S18/V14/Rqg50-sv1) and one in Convolvulus arvensis (tuf-b1/S1/V2-TA/Rqg31-sv1), whereas one was shared by two hosts, Crepis foetida and Daucus carota (tuf-b1/S1/V2-TA/STOL-sv1). Naturally infected D. europaea successfully transmitted the tuf-b1/S1/V2-TA/STOL type to five grapevines and six periwinkles, tuf-b1/S1/V2-TA/Rqg31 to one grapevine, and tuf-b1/S1/V2-TA/Rqg50 to one periwinkle, indicating that D. europaea is an intermediate vector in CaPsol epidemiological cycles.

Natural habitat and vegetation types of river gravel bars in the Caucasus Mountains, Georgia

River gravel-bar habitats are highly endangered. They are still well-preserved in the Caucasus, but developing conservation strategies is burdened by the lack of data from this region. We studied vegetation and habitat types on gravel bars of 22 rivers in Georgia, including successional stages from open early-successional herbaceous vegetation to scrub. We distinguished five vegetation types based on vegetation physiognomy and β-flexible clustering of species composition, and described them as phytosociological vegetation units: Early-successional herbaceous vegetation at higher elevations was described as the new association Epilobietum colchici and that at lower elevations as the Petrorhagia saxifraga–Crepis foetida community. The grassland dominated by Calamagrostis pseudophragmites and scrub vegetation were assigned to the associations previously described from Central Europe (Tussilagini farfarae-Calamagrostietum pseudophragmitae, Salici purpureae-Myricarietum germanicae and Salici incanae-Hippophaetum rhamnoidis). We established diagnostic plant species for each type using the fidelity calculation and related these types to environmental variables. We further compared them with the previously published data on gravel-bar vegetation from the Russian part of the Caucasus and with European systems of habitat classification. This study demonstrates that vegetation and habitat types occurring in Georgia correspond to those recognized earlier in Europe, and can be easily linked to the European systems of habitat classification. Unlike in other parts of Europe, these habitats are still well-preserved on rivers with natural hydrological dynamics, but they are threatened by plans of dam building and other river regulations. Our study provides baseline data for developing conservation strategies for the Caucasian gravel-bar habitats.

Separation of triacylglycerols containing allenic and acetylenic fatty acids by enantiomeric liquid chromatography-mass spectrometry

Triacylglycerols (TAGs) containing less common fatty acids (FAs) were isolated from the seeds of three plants (Santalum album, Crepis foetida, and Leucas aspera). These FAs had allenic (laballenic acid, Lb) and acetylenic (crepenynic, C; ximenynic acids, Xi) bonds. TAGs were analyzed on reversed-phase and chiral columns. High-resolution tandem mass spectrometry identified TAGs by positive electrospray ionization (ESI+). Twenty-two molecular species of TAGs isolated from the seed oil of Santalum album were separated by RP-HPLC and chiral HPLC methods and identified by positive electrospray ionization tandem MS detection (ESI+-MS). Two major enantiomers, i.e., sn-OOLb and sn-LLLb (O represents oleic acid; and L represents linoleic acid), were synthesized from the appropriate phosphatidylcholines. This allowed the identification of enantiomers after separation by chiral chromatography by tandem mass spectrometry. Similarly, TAGs from the seeds of Crepis foetida, and Leucas aspera were analyzed by reversed-phase chromatography and identified by mass spectrometry. Four enantiomers (sn-OOC, sn-LLC, sn-OOXi, and sn-LLXi) were synthesized. A total of six and three enantiomers of TAGs containing crepenynic and ximenynic acids, respectively, were identified by chiral column analysis. The retention times of TAGs containing allenic and acetylenic bonds were always greater on the reversed-phase column than TAGs with the same number of carbon atoms and the same unsaturation (e.g., LLL versus LLLb). From the chiral column, the regioisomers and enantiomers were eluted in the order of symmetric-asymmetric-asymmetric (i.e., sn-OCO, sn-COO, and sn-OOC). Through tandem mass spectrometry, we were able to identify and distinguish regioisomer [DAG]+-type ions, i.e., [MNH4NH3RCOOH]+, that can be considered diagnostic. Unfortunately, enantiomers and TAGs with the same numbers of carbon atoms and the same unsaturation levels have identical mass spectra, such as LLL and LLLb.

Role of plant-specialized Hyalesthes obsoletus associated with Convolvulus arvensis and Crepis foetida in the transmission of ‘Candidatus Phytoplasma solani’-inflicted bois noir disease of grapevine in Serbia

Bois noir (BN), a grapevine yellows disease induced by ‘Candidatus Phytoplasma solani’, is spreading and diversifying in several wine-producing regions of Europe, causing increased yield losses and economic concerns. The planthopper Hyalesthes obsoletus (Hemiptera: Cixiidae) is a major vector of the pathogen that causes BN disease in grapevine. Recent studies suggest that epidemiology of BN is affected by the interaction of specific host races of H. obsoletus with weedy host plants that serve as reservoirs for the pathogen. Since BN is common in grape-growing regions of Serbia, a survey was conducted during 2015–2016 to evaluate the host-plant association and vector role of H. obsoletus in central and eastern regions. We tested populations of H. obsoletus associated with Convolvulus arvensis (field bindweed) a known host for the vector and pathogen and Crepis foetida (stinking hawk’s-beard) a newly identified host in southeastern Europe. Molecular phylogenetic analyses of H. obsoletus collected from C. arvensis and C. foetida using the mtDNA COI marker determined that the two populations had a genetic divergence of 1.4%. Transmission trials confirmed the vector role of C. arvensis-associated H. obsoletus and identified C. foetida-associated populations as a new and efficient host-specialized vector of BN. Each of the two host-specialized vector populations transmitted ‘Ca. P. solani’ to its original host (C. arvensis or C. foetida) and to grapevine cv. Chardonnay. Multilocus genotyping of the transmitted phytoplasma isolates based on tuf/stamp/vmp1 ‘Ca. P. solani’-specific loci indicated pathogen segregation according to the host-plant association of the vector. All isolates transmitted by C. foetida-associated H. obsoletus were of the STOL genotype (tuf-b/STOL/V2-TA), while the C. arvensis-associated population transmitted several genotypes: tuf-b/Rqg50/V4, tuf-b/Rqg50/V14, tuf-b/Rqg31/V14 and tuf-b/Vv24/V14. This study provides evidence of a new independent BN epidemiological cycle of tuf-b ‘Ca. P. solani’ strain in the Balkan region, sourced by C. foetida and transmitted by its associated H. obsoletus population.

Widespread plant specialization in the polyphagous planthopper Hyalesthes obsoletus (Cixiidae), a major vector of stolbur phytoplasma: Evidence of cryptic speciation.

The stolbur phytoplasma vector Hyalesthes obsoletus is generally considered as a polyphagous species associated with numerous wild and cultivated plants. However, recent research in southeastern Europe, the distribution centre of H. obsoletus and the area of most stolbur-inflicted crop diseases, points toward specific host-plant associations of the vector, indicating specific vector-based transmission routes. Here, we study the specificity of populations associated with four host-plants using mitochondrial and nuclear genetic markers, and we evaluate the evolution of host-shifts in H. obsoletus. Host-plant use was confirmed for Convolvulus arvensis, Urtica dioica, Vitex agnus-castus and Crepis foetida. Mitochondrial genetic analysis showed sympatric occurrence of three phylogenetic lineages that were ecologically delineated by host-plant preference, but were morphologically inseparable. Nuclear data supported the existence of three genetic groups (Evanno’s ΔK(3) = 803.72) with average genetic membership probabilities > 90%. While populations associated with C. arvensis and U. dioica form a homogenous group, populations affiliated with V. agnus-castus and C. foetida constitute two independent plant-associated lineages. The geographical signal permeating the surveyed populations indicated complex diversification processes associated with host-plant selection and likely derived from post-glacial refugia in the eastern Mediterranean. This study provides evidence for cryptic species diversification within H. obsoletus sensu lato: i) consistent mitochondrial differentiation (1.1–1.5%) among host-associated populations in syntopy and in geographically distant areas, ii) nuclear genetic variance supporting mitochondrial data, and iii) average mitochondrial genetic distances among host-associated meta-populations are comparable to the most closely related, morphologically distinguishable species, i.e., Hyalesthes thracicus (2.1–3.3%).

A profile of chromosome counts, male meiosis and pollen fertility in 45 species of Asteraceae from Parvati Valley in Kullu district, Himachal Pradesh

Chromosome counts including male meiotic studies have been made on 45 species (125 accessions) of Asteraceae collected from the Parvati Valley, Kullu district, Himachal Pradesh. Crepis foetida (n = 5) and Senecio pedunculatus (n = 20) have been counted chromosomally for the first time at global level. The genus Phagnalon has been worked out for the first time from India (P. niveum, n = 9). New chromosome counts/cytotypes have been reported for Gerbera lanuginosa (2n = 4x = 48), Gynura cusimbua (2n = 2x = 16) and Inula grandiflora (2n = 4x = 32). Intraspecific euploid cytotypes have been reported for the first time in Inula grandiflora (2x,4x). Three intraspecific euploid cytotypes (2x,3x,4x) have been reported from the valley in Taraxacum officinale complex. The triploid taxa re-recorded presently for Erigeron annuus (2n = 27), Eupatorium adenophorum (2n = 51) and Taraxacum officinale (2n = 24) exhibit abnormal meiotic course and high pollen sterility but seem to have reproduced successfully through apomictic means. Presence of multivalents in the 4x cytotype of Chrysanthemum leucanthemum (2n = 36) indicates the segmental allotetraploid nature of the taxon. Phenomenon of cytomixis involving chromatin transfer among neighboring meiocytes and associated meiotic irregularities have been detected in Artemisia maritima (n = 9), Aster peduncularis (n = 27), Crepis foetida (n = 5), Erigeron annuus (2n = 27), Inula grandiflora (n = 8), Lactuca dolichophylla (n = 8), Prenanthes brunoniana (n = 8), Senecio graciliflorus (n = 20) and S. rufinervis (n = 20). In the rest of the species, the present findings substantiate earlier chromosome reports from other parts of Himalayas in India.

Crepis foetida L. subsp. rhoeadifolia (Bieb.) Celak. as a source of multifunctional agents: Cytotoxic and phytochemical evaluation

The cytotoxic, anticholinesterase, antityrosinase and antioxidant effects of methanol extract from the flower of C. foetida subsp. rhoeadifolia (CFRME) were evaluated. The cytotoxic effect was investigated using HepG2, Caco-2, MCF-7 and MCF-10A cell lines. Enzyme inhibitory activities were tested by spectrophotometric methods. Different chemical assays were used to determine the antioxidant effects. In addition, phenolic constituents were quantified. High-performance liquid chromatographic (HPLC) analysis revealed that chlorogenic acid was the major phenolic component in the extract. The extract showed a strong antiproliferative, antioxidant, and anticholinesterase and antityrosinase effects. These findings suggest that C. foetida subsp. rhoeadifolia may be considered as a source of ingredients that can be used as food supplements.

Antioxidant Activity And Phytochemical Screening Of Some Asteraceae Plants

Crepis foetida subsp. rhoeadifolia, Erigeron caucasicus subsp. venustus, Hieracium bornmuelleri, Leontodon crispus var. asper, Pilosella hoppeana subsp. testimonialis and Reichardia glauca belonging to the Asteraceae family, were evaluated for their antioxidant activities and phytochemical analysis of the tested extracts was carried out in current study. Antioxidant activities were investigated by using 1,1diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging assay and measuring malondialdehyde (MDA) levels. Chemical composition of the extracts was investigated by using some standards such as; phenolic acids; chlorogenic acid, caffeic acid, ferulic acid, rosmarinic acid, p-coumaric acid and flavonoids; apigenin, luteolin, quercetin, hyperoside, rutin, hesperidin by validated HPLC method. All the tested extracts exhibited antioxidant activity in DPPH radical scavenging test. The aerial part extracts of P. hoppeana subsp. testimonialis, Crepis foetida subsp. rhoeadifolia and both aerial parts and roots of Leontodon crispus var. asper were determined as the most active. The highest inhibitory effect of Leontodon crispus var. asper roots was also revealed by measuring MDA levels. According to the phytochemical analysis chlorogenic acid was detected in all species investigated except for Reichardia glauca aerial parts.

Crepis foetida L.: New host plant of cixiid planthopper Hyalesthes obsoletus Signoret 1865 (Hemiptera: Cixiidae), vector of stolbur phytoplasma

Epidemiology of plant diseases caused by phytoplasmas depends on vector's biology and its preference to the host plant. Grapevine yellows (GY) caused by stolbur phytoplasma (16SrXII-A subgroup, 'Candidatus Phytoplasma solani'), during last 15 years became one of the economically most important diseases of the grapevine in Europe. The cixiid plant­hopper Hyalesthes obsoletus Signoret (Hemiptera: Cixiidae) is a principle vector of stolbur phytoplasma and has the main influence on the incidence of the disease and yield loses in the vineyards. Epidemiological cycle of the Bois Noir (BN) is determined by the host plant of the H. obsoletus which is primal source of the disease in the vineyard and it affects presence of the pathogen in the insect's population. Presence of stolbur phytoplasma and symptoms of the BN disease is registered in all wine growing regions in Serbia. This research was focused toward determining host plants of the H. obsoletus and its ge­netic characteristics in order to determine epidemiological characteristics of BN in Serbia. Based on this field research, along with populations associated with previously known host plants nettle (Urtica dioica) and bindweed (Convolvulus arvensis), new host plant association with Crepis foetida L (Asteraceae) was registered on several localities in east and south Serbia. Genetic structure of H. obsoletus populations associated with specific host plants is analyzed in order to obtain precise information about epidemiological cycle of stolbur phyto­plasma in agroecosystems in Serbia. According to results of the three analyzed mtDNA regions, genetic differentiation is present between H. obsoletus populations associated with C. arvensis and U. dioica on the one and C. foetida on the other side. Domination of one of these two genotypes in nature and distribution of the host plants provides the basis for further research of the potential vector ability and characterization of the stolbur phytoplasma which is being transmitted by H. obsoletus and epidemiological cycles related to the new host plant in Serbia.

IN VITRO CYTOTOXIC AND ANTIOXIDANT ACTIVITIES OF SOME PLANT EXTRACTS ON DIFFERENT HUMAN CANCER CELL LINES

s. PHYTOPHARM 2012 M 50 Obzory po kliniceskoj farmacologii i lekarstvennoj terapii [Reviews of clinical pharmacology and drug therapy] ТОМ 10/2012/2 concentration of OPCs and antiradical activity in tests “in vitro”. More than 40 samples of food and medicinal plants were investigated. Total polyphenolics were determined employing folin-Ciocalteu photometric method, sum of OPC — by bate-Smith acid butanol assay, free radical scavengic activity (fRSA) — by the dPPh test. The study was carried out to search the antioxidant ingredients for diet enrichment. No direct correlation between the antioxidant in vitro tests and the content of polyphenolic compounds and proanthocyanidins has been found. On the basis of the above test results the feasibility of using products based on cinnamon, red beans, cocoa and blueberry for diet enrichment has been shown. IN VITRO CYTOTOXIC AND ANTIOXIDANT ACTIVITIES OF SOME PLANT EXTRACTS ON DIFFERENT HUMAN CANCER CELL LINES © El-Hallouty Salwa M. , Khalifa Noha S. , Barakat H. M. , Salim Dina 2 Pharmacognosy Department, National Research Centre, Giza, Cairo, Egypt Botany Department, Ain Shams University, Cairo, Egypt This study involves a bioassay screening of 22 methanol extracts from 19 plants that are commonly used in Egypt for many purposes based on their ethnic values. The aim of this study is to evaluate the cytotoxic and antioxidant activities of 22 methanol extracts. The methanol plant extracts were tested in vitro against four human cancer cell lines (by using MTT method) to determine their cytotoxic effect. The cell viability was examined after 24 h exposure to 100 μg/ml of the extract in the medium. Negative (dimethyl sulfoxide) and positive (Annonacherimolia methanol extract) controls were simultaneously used. Moreover, the antioxidant effect was determined using dPPh assay. Extracts showing cytotoxic and antioxidant activities were further subjected to determine their (lethal concentration) lC 50 and lC 90 values. Confirmed in vitro cytotoxic activity was found in four plant extracts. in hepG-2, Cympopogonproximus, Perseaamericana fruits and Vignaunguiculataseeds showed lC 50 = 57.4, 13.3 and 56.4, respectively. in A-549, Perseaamericana fruits and Tabernamontanadivaricata leaves showed lC 50 = 35.4 and 70.7, respectively. in hT-29, Cympopogonproximus, Perseaamericana fruits and Tabernamontanadivaricata leaves showed lC 50 = 58.6, 22 and 67.5, respectively. in MCf-7, Perseaamericana fruits showed lC 50 = 54.5. In vitro antioxidant activity was confirmed in three plant extracts Ceratoniasiliqua leaves, Perseaamericana leaves, Abrusprecatorius seeds showed lC 50 = 10.6, 46.5 and 25.7, respectively. 5 Extracts out of the 22 studied methanol extracts exhibited potent antioxidant properties when tested at the concentration of 100 ppm against dPPh. The methanol extract of Persea americana leaves, Abrus precatorius seeds, Ceratonia siliqua leaves had lC50 = 46.5, 25.7, 10.6 μg/ml, respectively Table 4. The methanol extracts of Ocimum basillicum and hilianthus annuus had lost their activity below 100 ppm. The plants under study may represent promising natural sources for cytotoxic and antioxidant drug discovery. PHYTOCHEMICAL SCREENING AND ANTIOXIDANT CAPACITIES OF SOME COMPOSITAE PLANTS © Ergene B. , Bahadir Acikara O. , Bakar F. , Saltan G., Nebioglu S. 2 Ankara University Faculty of Pharmacy, Department of Pharmacognosy, Ankara, Turkey Ankara University Faculty of Pharmacy, Department of Biochemistry, Ankara, Turkey Asteraceae is one of the families which include many members containing phenolic compounds (1). The beneficial effects of many of the phenolics in human health have been attributed to their reactive oxygen and nitrogen scavenging and antioxidant capacity. The consumption of vegetables, fruits and flavonoid-rich beverages has been reported to prevent against neurodegenerative diseases, cancer and aging (2). Phenolic compounds have antioxidant potential due to their tendency to act as reducing agents, hydrogen donors, singlet oxygen quenchers and metal chelators, chelating agents which can bind metal ions, could be added to enhance the activity of natural preservatives in food stuffs (2, 3, 4). in this study, the antioxidant activity of three members of Asteraceae family; Crepis foetida subsp. rhoeadifolia, Leontodon crispus var. asper and Pilosella hoppeana subsp. testimonialis were evaluated using 1,1-diphenyl-2-picrylhydrazyl (dPPh) free radical scavenging assay and measuring malondialdehyde measuring levels. in dPPh free radical scavenging activity as-

Assessment of antioxidant, antibacterial, antimycobacterial, and antifungal activities of some plants used as folk remedies in Turkey against dermatophytes and yeast-like fungi

Twenty-seven aqueous extracts obtained from 21 plants used in the treatment of respiratory tract infections as folk remedies in Turkey were investigated for their relative total phenolic contents and antioxidant, antibacterial, antimycobacterial, and antifungal activities. Antibacterial and antifungal activities against dermatophytes and yeast-like fungi were determined using the microdilution method. Antibacterial activity of all extracts was more pronounced against gram-positive bacteria than against gram-negative bacteria. These extracts also exhibited higher antifungal activity against Candida krusei than ketaconazole. Six extracts displayed antidermatophytic activity against Epidermophyton floccosum, while only 3 extracts were highly active against Trichophyton rubrum. The extracts showed strong activity against both Mycobacterium tuberculosis and Mycobacterium avium, except for the Teucrium polium, Urtica dioica, Salvia fruticosa, S. verticillata, Rosa canina (flower, shoot, and root), Rubus sanctus, and Crepis foetida extracts. Additionally, all extracts exhibited antioxidant activity in DPPH assay except for the Primula vulgaris, Ononis spinosa, Nepeta italica, Hedera helix, Lantana camara (orange flowers), U. dioica, and C. foetida extracts. The highest total phenolic content was observed in R. canina root extract. No correlation was observed between biological activities and the amount of phenolic compounds. All plants used in this study could be potential sources of new antimicrobial agents.

Effects of litter and standing biomass on growth and reproduction of two annual species in a Mediterranean old‐field

Summary We tested the hypothesis that the competitive ability of a plant changes during its lifetime, by evaluating variations in the relative influence of standing biomass and litter on plant performance. Seedlings of two annual herbaceous species (‘targets’), of contrasted life‐forms (Crepis foetida and Bromus madritensis) were transplanted into an old‐field. The competitive ability of seedlings, vegetative and reproductive plants towards neighbours was recorded over one growing season. Fourteen traits related to plant morphology, growth and reproduction were measured to assess the competitive ability of targets. Relationships among traits were characterized to identify a set of traits as a surrogate of target competitive ability. The two target species responded similarly. Early growth was facilitated by litter and, to a greater degree, by vegetative biomass. Thereafter, the effect of neighbouring vegetation on target performance was negative, with a maximum depressing effect on reproduction (especially seed number and date of flowering) despite a weak facilitative effect of litter. Plant basal diameter, measured at peak growth period, and total number of inflorescences per plant, were found to predict growth and reproductive components of competitive ability, respectively. Assessing the effects of competition for population success from the response of vegetative plants will underestimate its importance because competition appears to exert its maximal impact on seed production.