121 research outputs found
\u3cem\u3eCuscuta Jepsonii\u3c/em\u3e (Convolvulaceae): An Invasive Weed or an Extinct Endemic?
Despite their ecological significance, parasitic plants face more conservation challenges than do autotrophic plants. This is especially true for the groups that include weedy or invasive species such as Cuscuta. While approximately half of the Cuscuta (dodders) species may require conservation measures, the genus as a whole is sometimes posted on governmental lists of noxious or quarantine weeds. Our study challenges this stereotype and uses the case of C. jepsonii (Jepson’s dodder) to illustrate the precarious biodiversity and conservation status faced by many dodder species. Until now, Jepson’s dodder has been known only from its type collection. Consequently, its phylogenetic affi nities, morphological variation, and ecology have remained unknown, and the species is currently ambiguously considered either synonymous to the invasive North American weed C. indecora or to an extinct endemic from California. Using molecular data from newly found collections, we infer that C. jepsonii belongs to C. californica species complex, instead of C. indecora clade. Also, we discuss the conservation of this species within the broader biological and ecological context of Cuscuta in general
Evolutionary History and Taxonomy of the \u3cem\u3eCuscuta umbellata\u3c/em\u3e complex (Convolvulaceae): Evidence of Extensive Hybridization from Discordant Nuclear and Plastid Phylogenies
The Cuscuta umbellata complex is one of the 15 major clades recently circumscribed in C. subg. Grammica. Most of its members occur in North AMerican and the Caribbean (C. desmouliniana, C. lacerata, C. lacerata, C. leptantha, C. liliputana, C. odontolepsis, C. polyanthemos, C. tuberculata, C. umbellata), but three species (C. acuta, C. membranacea, C. umbellata) grow in South America, and one (C. hyalina) is found as a native species in India, Pakistan and Eastern to South Africa. Basic morphology, scanning electron microscopy and sequence data from the nuclear internal transcribed spacer (ITS) and the plastid trnL-F region were used to reconstruct the phylogeny, gain a better understanding of the evolutionary history, and determine species boundaries. Our results show that in its currently accepted delimitation C. umbellata is polyphyletic. Discordances betwen phylogenies derived from plastid and nuclear data strongly suggest that at least four independent hybridization events have occurred in the evolution of this species group, rendering relationships among its members more complex than previously thought. One of these reticulation events involves C. umebellata var. relexa, a taxon that has been considered synonymous to C. umebllata var. umbellata in the last decades. This hybrid is morphologically intermediate but distinct from its putative parents, C. odontolepsis or C. acuta on the maternal side, and C. umbellata (var. umbellata) on the paternal side, which supports its treatment as a new species, C. legitima. Cuscuta umbellata is further redefined to exclude C. umbellata var. dubia, which is merged into C. desmouliniana. A new classification is provided, together with an identification key, descriptions, illustrations, and geographical distributions for the twelve species of the clade
The Biology of Canadian Weeds. 131. \u3cem\u3ePolygonum aviculare\u3c/em\u3e L.
A review and assessment of biological information as well as personal data are provided for Polygonum aviculare in Canada. The species has been revised taxonomically and the six subspecies that occur in Canada are presented. Three of the subspecies, P. aviculare subsp. aviculare, P. aviculare subsp. neglectum and P. aviculare subsp. depressum are weeds introduced to Canada from Europe. A fourth subspecies, P. aviculare subsp. buxiforme is apparently native to North America. The geographical distribution of the latter four subspecies is very wide. Plants exhibit a high phenotypic plasticity and genetic variability, and they easily adapt to a multitude of agrestal and ruderal habitats. The seeds have a variable dormancy and polymorphic germination as a result of heterocarpy, genetic and environmental factors. In other areas (Europe), the species has developed resistance to triazines. Plants are hosts to nematodes, viruses, and fungi that also affect cultivated plants
The Biology of Canadian Weeds. 126. \u3cem\u3eAmaranthus albus\u3c/em\u3e L., \u3cem\u3eA. blitoides\u3c/em\u3e S. Watson and \u3cem\u3eA. blitum\u3c/em\u3e L.
A review of biological information is provided for three species of the genus Amaranthus: A. albus L., A. blitoides S. Watson and A. blitum L. The last species has been revised taxonomically and a new subspecies for Canada is presented—A. blitum subsp. emarginatus (Moq. ex Uline & Bray) Carretero, Munoz Garmendia & Pedrol. Amaranthus albus and A. blitoides are native to the U.S.A. and introduced to Canada. Both species are annual ruderal and agrestal weeds. During the past 100 yr the two species have spread across most provinces of Canada, but the greatest frequency and abundance have been recorded in Saskatchewan. Originating from Europe, Asia and North Africa, A. blitum was initially considered a non-persistent species. The present study shows that A. blitum especially, subsp. emarginatus, has continued to spread in Québec. The three species are alternate hosts to many insects, nematodes, viruses, bacteria and fungi that affect cultivated plants. In other areas (U.S.A., Europe and Asia), the three species have developed multiple resistance to triazine and acetolactate-synthase-inhibiting herbicides
The Biology of Canadian Weeds. 133. \u3cem\u3eCuscuta campestris\u3c/em\u3e Yuncker, \u3cem\u3eC. gronovii\u3c/em\u3e Willd. ex Schult., \u3cem\u3eC. umbrosa\u3c/em\u3e Beyr. ex Hook., \u3cem\u3eC. epithymum\u3c/em\u3e (L.) L. and \u3cem\u3eC. epilinum\u3c/em\u3e Weihe
Cuscuta spp. (dodders) are rootless, holoparasitic herbs with filiform stems attached to the host by numerous haustoria. In Canada, Cuscuta gronovii is the most common native species of the genus followed by Cuscuta campestris and C. umbrosa. Cuscuta epithymum and C. epilinum, both introduced species in Canada, occur occasionally. Infestation by Cuscuta spp. can result in serious yield losses and dodders are listed as noxious weeds in British Columbia, Ontario and Québec, and as restricted weeds in Alberta. These plants have evolved special adaptations to ensure their success: germination occurs late in the season when potential hosts are already established; seedlings selectively forage in plant communities and they may survive relatively long periods during the autotrophic stage. Invasion occurs via extremely elaborate mechanisms designed to match the biological processes of their host and bypass defense mechanisms. The principal means of dispersal of Cuscuta weeds world-wide (including Canada) has been through contaminated seeds of previously infested forage legumes. In other areas (e.g., Israel), C. campestris has developed resistance to ALS inhibitors (chlorsulfuron, and sulfometuron-methyl) and AABI herbicides. Complete descriptions and illustrations are provided for discussed species
COMMERCIAL ACTIVITY IN SUCEAVA. HISTORY, EVOLUTION AND PERSPECTIVES OF TOURISTIC CAPITALIZATION
This research aims to highlight the evolution of commerce activity in Suceava city. It should be noted that for this town, the commerce is a historical legacy because since from its documentary attestation (the fourteenth century) Suceava was one of the largest commercial centers of the Moldavian Principality. Today, after the period of the communist regime characterized by a strong industrialization, Suceava has become a powerful trade center. The paper presents the transition of Suceava from a commercial dimension perpetuated since medieval times until the late nineteenth - early twentieth century to an industrial dimension started timidly in the early twentieth century and continued into an advanced form after the Second World War, during the communist regime. The paper also presents the return to a commercial dimension, after the communist regime. Our research does not hesitate to present the economy transformation in a mainly tertiary one, in terms of changing the functionality of some areas in the city that once represented some strong industrial areas. Although in the North-East Region and, therefore, in Suceava, the salary level was one of the lowest nationally, the area became attractive to shopping centers developers, which started in 2002 to invest in opening of large stores instead of former industrial enterprises. In a short time, the area of modern retail space per thousand people became the largest in the country. Given the historical and current context in which commerce prevails in the local economy, we chose to make a series of proposals for the expansion of tourism in Suceava in correlation with the activity of shopping centers from the local market
CONSUMPTION-BASED ECONOMY. THE CASE OF ROMANIA IN THE LAST TWO DECADES
Romania has entered an era of consumption and its stimulation remains one of the solutions always initiated to support the national economy, especially given that exports are declining due to euro-market problems - the main market for Romanian products.In this context, this paper aims to make a foray in time, starting with the issue of de-industrialization of Romania and subsequently with the transformation of Romanian economy into a tertiary one, accompanied by the simultaneous development of the economy based on consumption. In other words, the role of this paper is to present (using statistical data), the causes of de-industrialization of Romania, elements on the evolution of the tertiary industry, and some features and pitfalls of consumer-based economy. Also, the content of this article does not hesitate to emphasize the author's personal views about the studied phenomenon
Delimitation of Major Lineages within \u3cem\u3eCuscuta\u3c/em\u3e Subgenus \u3cem\u3eGrammica\u3c/em\u3e (Convolvulaceae) using Plastid and Nuclear DNA Sequences
Subgenus Grammica, the largest and most diverse group in the parasitic genus Cuscuta, includes ~130 species distributed primarily throughout the New World, with Mexico as its center of diversity. To circumscribe the subgenus ans assess the relationships among its major lineages, we conducted the first phylogenetic study of Grammica using plastid trnL F and nrITS sequences from a wide taxonomic sampling covering its morphological, physiological, and geographical diversiity. With the exception of of one species belonging elsewhere, the subgenus was found to be monophyletic. The results further indicate the presence of 15 well supported major clades within Grammica. Some of those lineages correspond partially to earlier taxonomic treatments, but the majority of groups are identified in this study for the first time. The backbone relationships among major clades, however, remain weakly supported or unresolved in some cases. The phylogenetic results indicate that the fruit dehiscence character is homoplastic, thus compromising its value as a major taxonomic and evolutionary feature. While several striking cases of long distance dispersal are inferred, vicariance emerges as the most dominant biogeographical pattern for Cuscuta. Species placed within one of the caldes with a predominantly South American distribution are hypothesized to have substantially altered plastid genomes
The Biology of Canadian Weeds. 126. \u3cem\u3eAmaranthus albus\u3c/em\u3e L., \u3cem\u3eA. blitoides\u3c/em\u3e S. Watson and \u3cem\u3eA. blitum\u3c/em\u3e L.
A review of biological information is provided for three species of the genus Amaranthus: A. albus L., A. blitoides S. Watson and A. blitum L. The last species has been revised taxonomically and a new subspecies for Canada is presented—A. blitum subsp. emarginatus (Moq. ex Uline & Bray) Carretero, Munoz Garmendia & Pedrol. Amaranthus albus and A. blitoides are native to the U.S.A. and introduced to Canada. Both species are annual ruderal and agrestal weeds. During the past 100 yr the two species have spread across most provinces of Canada, but the greatest frequency and abundance have been recorded in Saskatchewan. Originating from Europe, Asia and North Africa, A. blitum was initially considered a non-persistent species. The present study shows that A. blitum especially, subsp. emarginatus, has continued to spread in Québec. The three species are alternate hosts to many insects, nematodes, viruses, bacteria and fungi that affect cultivated plants. In other areas (U.S.A., Europe and Asia), the three species have developed multiple resistance to triazine and acetolactate-synthase-inhibiting herbicides
Stem Morphology and Anatomy in \u3cem\u3eAmaranthus\u3c/em\u3e L. (\u3cem\u3eAmaranthaceae\u3c/em\u3e)—Taxonomic Significance
The range of variation within the genus Amaranthus L. (Amaranthaceae) is described for a number of stem characters including: morphology, epidermis, primary stem vasculature and mechanism of secondary growth. The results provide new characters (phyllotaxy, complexity of leaf vascular supply and relative amount of secondary growth) that support (1) a new infrageneric classification (subgenus Amaranthus vs subgenus Albersia (Kunth)Gren. & Dodr.), and (2) the separation within the “hybridus” complex of cultivated amaranths (A. caudatus L., A. cruentus L., and A. hypochondriacus L.) from their presumed wild ancestors (A. hybridus L. subsp. quitensis (Kunth) Costea & Carretero, A. hybridus L. subsp. hybridus and A. powellii S. Wats. subsp. powellii respectively)
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