Imperfect flowers are flowers that only have one set of reproductive organs, so they are either male or female. There are two types of imperfect flowers. Staminate flowers contain only stamens, the male reproductive part of the flower. Pistillate flowers only contain the pistil, or female, reproductive part. Perfect flowers, on the other hand, such as roses, are flowers that contain both a pistil and stamens, and therefore are both male and female. A third type of flower, the incomplete flower, can be either perfect or imperfect, but is missing one of the four major parts of a flower: the pistil, stamens, petals or sepals.

While perfect flowers can reproduce entirely within one bloom, imperfect flowers need two separate flowers in order to pollinate themselves and create seeds. Imperfect flowers may be pollinated by animals, insects, weather or humans, but they will always need some sort of outside facilitation in order to reproduce.

Imperfect flowers grow on one of two types of plants. Monoecious plants have both male and female blooms on one plant. Two examples of monoecious plants are the corn plant and the pecan tree. The second type of plant on which imperfect flowers grow is the dioecious. This type of plant is either male or female; different sexes of dioecious must therefore be planted close to each other in order to reproduce. Some examples of dioecious plants are the holly bush and pistachio tree. In this instance, there has to be a lot of intervention by outside forces, such as insects, in order to pollinate the female flowers.

Kiwis have a distinction among dioecious plants as they can contain staminate flowers only, or perfect flowers with both reproductive organs. Although imperfect flowers may be a bit harder to cultivate because they need more attention for pollination, they are still an important part of horticulture.