A pasture field in Vassouras, State of Rio de Janeiro, was analysed from the viewpoint of plant sociology. This study is partt of a project being developed by several professors from the Institute of Biology of UFRRJ on the Biology and Ecology of Hemiptera of the genus Dysdercus. Quadrats of one square meter were located in the fie ld and for each one, data of frequency, density and dominance were collected. The sum of the relative value of this data produces the IVI (Importance Value Index). The grasses making up the pasture added up to 114,9 IVI. All grasses summed up gave an IVI of 161,18, grass species infesting the pasture were considered associated forage plants. Wedelia paludosa DC. is the species of Dicotyledoneae with the highest IVI = 22,65. During the high temperatures and rainfall months, associated with intense grazing of the forage plants, this species can develop until it partially covers the field. Although 27 families and 67 species were counted in the pasture field, only 37 are represented in the quadrats; the others were considered sporadic in the community.
Pasture; weeds; plant sociology