Ipomoea aristolochiaejólia (H.B.K.) Don. is a common weed of several crops ia the states of Rio Grande do Sul, Paraná, São Paulo and Minas Gerais. Its seeds often occur among the seeds of many crops. Testa were conducted to study water imbibition capacity and the influence of mechanical scarification as well as alternate and constant temperatures on seed germination with the purpose to know the species biology. In imbibition test, the seeds were immersed ia water at room temperature for 2, 4, 6, 8, 24 and 48 hours. After 24 and 48 hours, 60% remained hard and most of the imbibed seeds had germinated. In germination testa, nonscarified seeds were compare~l with scarified ones for 2, 5, 8 and 11 seconds, ia the following temperatures: 20/30, 20/35, 20 and 250C. There was no difference among scarification treatments ia the temperatures tested and germinatíon ranged from 85 to 98%. For nonscarified seeds, alternate temperatures favored the germination (88 and 94%) with the higher percentage at 20/350C; at constant temperatures, germination dropped to 50%.