Examine a few flowers of any cucurbit plant and try to identify the staminate and pistillate flowers. Do you know any other plant that bears unisexual flowers ?

Explanation

Cucumber is a good example of Cucurbita.
Cucumber plants have separate male and female flowers.
A pistillate flower is distinct by appearance of a baby fruit at the base of the flower, while a male or staminate flower does not possess such baby fruit.
Another example of a unisexual flower is the flower of maize.
The male flower in maize can be distinguished from the female as it grows higher up the stem.
While the female flower remains on the lower part of the stem.