The study was carried out to evaluate the floristic composition and the phytosociological characteristics of a fragment of the natural forest of Astronium balansae Engl, in Bossoroca county, RS, Brazil. Seven 10x100m (1000m²) units were inventoried: 476 measured trees (CBH = 30cm) were distributed in 35 species and 25 families. The most important species were Astronium balansae, Myrcianthes pungens, Patagonula americana, Eugenia uniflora and Parapiptadenia rigida. The families Myrtaceae, Meliaceae and Euphorbiaceae were the most representative families in the forest fragment studied. The Shannon diversity index was 3.
floristic composition; fitosociology; pau-ferro