Resumo. This study aimed to elucidate the time of occurrence of flowers and fruits and the external and internal morphology of the flower, fruit and seed, and seedling and external changes of Diatenopteryx sorbifolia Radlk (Sapindaceae). The collection of botanical material and phenological observations were made on trees headquarters, located in the municipality of Frederico Westphalen, Rio Grande do Sul state, between March 2007 and March 2010. The study was conducted at the Seed Laboratory of the Department of Forest Sciences, Federal University of Santa Maria, RS state. The species flowered from September to October. The annual fruiting occurs from November to January, having anemochorous dispersion. There were irregularities in the production of fruits as the years and there is no synchronization between headquarters during the phenophases. The species has inflorescence thyrsus, pleiotirso, with small white flowers in color, hermaphrodites with ovarian super sincarpico, and bicarpelar uniovular, as well as male unisexual flowers. The fruit of siples, dry, indehiscent, brown color, is the type esquisocarpaceo, consisting of samarideos containing one to two seeds, ovoid, brown color, exalbuminate with axial embryo and fleshy cotyledons. The germination process started from the second day after sowing, germination is epigeal type. After 18 days, the seedling phanerocotyledonal is formed. The changes in conditions to be studied, are formed three months after sowing. The phenological characterization is morphological information that is relevant for the field identification of species, seed collection and analysis, as well as the production of seedlings.