Distribution and ecology of two Cuscuta species in Belgrade urban environment

Abstract

Distribution, viability and host preferences of " L. and " (L.) Murr, were studied to establish their ability to survive under synergistic influence of ecological factors, air pollutants and general temperateEcontinental climatic conditions of Belgrade. Concentrations of pollutants and microclimatic parameters relevant for this study were followed during the season. " species, being widespread and locally common throughout the area, are the most competitive and most adaptive selfgrown, allochtonous parasitic annuals, growing in various ruderal habitats of urban Belgrade areas. Local adaptation of two holoparasitic plants to their host plants, varied among populations. The census of the population of the Cuscuta species on the territory of New Belgrade without suburbs, revealed the presence of 112 individuals of " and 82 of " over the survey period. The greatest population density was recorded at the contours of the town, being frequently found upon hedges, waste places, hedgerows, bushy places, along the roadsides, on unmowed green areas, cemetery surroundings and similar ruderal habitats. The lowest population density, however, was observed along the central streets and bank of the river Sava. Their occurrence was extremely sporadic in the parks and squares. Of the total number of the individuals of " , were parasitic 26% on Urticaceae, 18% on Fabaceae, 5% on Asteraceae, 5% on Solanaceae and to a lesser extent on other families (Lamiaceae, Convolvulaceae, Chenopodiaceae, Rubiaceae, Malvaceae, Plantaginaceae, and Ranunculaceae). Of total number of individuals of " were growing 32% on Fabaceae, 5% on Lamiaceae, 2% on Caryophyllaceae, and occasionally on many other host plants (& #, , and % ). The last species very rarely parasitizes shrubs and grasses (" and 0 ). " has been shown to be highly expansive and competitive parasitic plant, but also markedly resistant to the disturbed or stressed urban habitats. The great occurrence on unmowed green areas in newly built city residential districts indicates to the expansiveness i.e. progressiveness of the population of the " in the area studied. " , described as invasive, are likely to spread into native flora or managed plant systems, develop selfsustaining populations and become dominant or disruptive to those systems.