One example of a perfect flower is the China rose, a variety of hibiscus. Others are lilies, apple and cherry blossoms, and flowers on legumes. Walnuts and chestnuts are examples of plants with imperfect flowers. Other examples of imperfect flowers include squashes, cucumbers, corn and grasses.
Flowering plants are angiosperms, or plants that reproduce sexually to form seeds inside fruits and flowers. The difference between perfect and imperfect flowers is their sex organs. Each perfect flower has both male and female reproductive organs and can self-pollinate. In some ways, this makes them hardier, as they don't depend on cross-pollinators to breed. Plants whose flowers have both sex organs are called “hermaphroditic.”
Imperfect flowers, which have only one gender of sex organ, are the most common among angiosperms. Because imperfect flowers are either male or female, they breed by cross-pollinating. Plants with imperfect flowers can be easily bred for color, to increase food yields and build resilience, or to breed out diseases. Imperfection also helps insure plants against genetic monotony, a condition where a single disease can wipe out an entire species. It is also possible to have both perfect and imperfect flowers on one plant. In this case the plant is considered polygamous.