Mendel counted 5,474 round or roundish peas in his monohybrid cross for seed shape. These were part of the F2 generation produced from crosses between pea plants with contrasting round and wrinkled seed forms.
Across the experiment, Mendel examined 7,324 seeds obtained from 253 hybrids. Of the total, 5,474 were round or somewhat rounded, while 1,850 were angular and wrinkled. The resulting ratio was about 2.96 to 1, closely matching the approximately 3:1 phenotype ratio predicted when a dominant trait and a recessive trait segregate.
The figure 7,324 is therefore the total number of seeds, not the number of round seeds. The smaller figure, 1,850, represents the wrinkled group. Mendel’s key insight was that the wrinkled trait had not disappeared in the first generation; it reappeared in the next generation when inherited factors separated.
Modern genetics explains the pattern through alleles and meiosis, although Mendel himself called the inherited units “factors.” Round seed shape was treated as dominant, while wrinkled shape was recessive.