Dominant and recessive
In a hybrid, the form of a trait that shows is called dominant and the one that stays hidden is called recessive. The terms are Mendel's own: dominirend and recessiv.
When Mendel crossed a pea variety with round seeds and one with wrinkled seeds, the hybrid bore only round seeds. For all seven traits he studied, the hybrid showed just one parent's form. He called the form that shows dominirend and the one that hides recessiv[1].
The hidden form is not lost. When the hybrids pollinated themselves, the recessive form came back: across all seven traits the totals were 14,949 dominant to 5,010 recessive, close to 3 to 1, and intermediate forms never appeared[1].
Carl Correns, one of those who brought Mendel's paper back to light in 1900, cautioned that not every pair of characters has a dominant member, so the rule could not be applied to all hybrids[2].
Related terms
- Self-pollinationThe pollination of a flower by its own pollen. Peas pollinate themselves before the flower opens, so stray pollen rarely gets in and a cross made by hand stays the cross intended.
- Law of segregationThe rule that the two differing hereditary elements in a hybrid separate when egg cells and pollen are formed, so that each receives one or the other. Mendel set it out in 1866; it was rediscovered in 1900.