A statistical study of four criteria applied to the genus Dactylis (Poaceae) enabled us to determine the individual meiotic behaviour of eight tetraploid populations. Those criteria were as follows: the percentage of rod and ring bivalents, the average number of tetravalents, the average number of chiasmata, and the distribution pattern of chromosomic formulas.Key words: Dactylis, populations, meiotic behavior, tetraploidy, cocksfoot.