Abstract: | The study of ruderal and segetal plant associations registered new impulses only during the first half of last century. These associations comprise synanthropic species whose existence and distribution are linked to human activities, as their name indicates (lat. “simul” – together; gr. “anthropos” – man). They may be autochthonous when they are parts of the Romanian flora, or allochthonous if belonging to other floras.
Synanthropic associations develop in townships and around them, on barren ground, at the border of roads and park alleys, in agricultural cultures and on their margins, in courtyards of habitations in rural sites, in green spaces between apartment houses in urban conditions, in green spaces of parks and gardens (more or less well managed) of the city, on courtyards of industrial enterprises, on the banks of lakes and rivers where fishing is practiced etc. Everywhere, where human activities are going on weeds are present, as are named popularly segetal and ruderal plants.
In current conditions anthropic influence on vegetal diversity is ever stronger, a consequence being the enhancing of adaptation capacity of weeds and the arising of resistant biotypes (Sorghum halepense (L.) Pers., Matricaria perforata MĂ©rat.), so that research on biology, ecology and arealogy of weeds becomes a stringent necessity.
Under certain circumstances weeds become significant competitors of agricultural crops and ornamental species. The main method in the struggle against weeds is the use of herbicides, substances which may act by secondary effects upon cultivated plants, sometimes over a long period, and implicitly upon people and animals which eat them. On the other hand utilization of herbicides or other means of control on a large scale could be “over-efficient” leading to the total disappearance of some segetal and ruderal species from the flora of Romania. |
