The unblended expression of two different alleles for a trait in the phenotype of heterozygous individual is called as

The unblended expression of two different alleles for a trait in the phenotype of a heterozygous individual is called Co-dominance.
Co-dominance, refers to a type of inheritance in which two versions (alleles) of the same gene are expressed separately to yield different traits in an individual.
Gregor Mendel discovered the phenomenon of co-dominance while studying polygenetic traits and their inheritance.