Oogamy is the form of sexual reproduction and it is a type of heterogamy. Also comes under the part of anisogamy. Oogamy is the fertilization process where the male gamete is received by the female and fusion occurs within the female gamete cell.

In it, the male and female gamete are not of same size and shape.

Such type of reproductive fertilization is observed in Gymnosperm, Bryophytes, and even Pteridophytes