Basics of Flower and Plant Structure

• A perfect (complete) flower has both the male and female parts in one flower. Examples are peas and lettuce.

• An imperfect (incomplete) flower has only the male or the female parts. Examples are cucumbers and pumpkins.
• Female parts are the stigma, style and ovary, which make up the carpel or pistil.
• Male parts are the anther and filament, which make up the stamen.


• A monoecious (one house) plant has both male and female flowers on the same plant. These can be complete or incomplete flowers. Examples are corn and tomatoes.
• A dioecious (two houses) plant has only the male or female flowers on each plant. Examples are asparagus and spinach.
• Inbreeding plants are those that can breed with themselves. Examples are beans and tomatoes.
• Outbreeding plants are those that breed with another plant. Some plants with perfect flowers must breed with another plant. Examples of outbreeders are broccoli and arugala.
• Self-sterile flowers are flowers that release pollen before the stigma of the same flower (and often all stigma on the same plant) is receptive. This is an evolutionary adaptation designed to preserve genetic diversity.
• Annuals are plants that complete their lifecycle in one year. Biennials complete their lifecycle in two years (seeds form in second year).
• Flowers are pollinated by wind, insects, or themselves.
• Inbreeding depression occurs when a plant is capable of self-pollinating but experiences decreased vigor as a result.
• Hybrid vigor is the opposite of inbreeding depression. This is when a plant is crossed with another with vigorous growth as the result.