Based on the reproductive organs present, a flower can be unisexual or bisexual.
When a flower contains both carpel and stamen, it is bisexual and produces both male and female gametes.
Example- Rose and Sweet pea.
Unisexual flowers only have one kind of reproductive organ either carpel or stamen, and they can only produce either male gamete or female gamete.
Example- Papaya and Corn.
Final Answer- Flowers having all four whorls that are sepal, petal, pistil, and the stamen is called bisexual flower and unisexual flower only have three whorls sepal, petal, and pistil/stamen.