Flower Structure
Flower structures are based on several features, including:
- The position of the ovary relative to the perianth (the combination of the corolla and the calyx).
- The presence of one or both of the male and female reproductive organs.
Position of the Ovary
- Ovary superior: The ovary is above the perianth; the sepals, petals, and stamens are inserted beneath the ovary. Examples: Borage Family, Boraginaceae, Mint Family, Labiatae. See Figure 1.
- Ovary inferior: The ovary is below the perianth; the sepals, petals, and stamens arise above the ovary. Sunflower Family, Compositae. See Figure 2.
Figure 1. Flower with Ovary in Superior Position
Figure 2. Flower with Ovary in Inferior Position
Reproductive Organs
The flowers shown in these figures are bisexual, that is, they have both male (stamen) and female (pistil) reproductive organs that are functional. Most cultivated plants have bisexual flowers. Some plant species have separate male and female flowers on the same plant, for example, corn, asparagus, and cucumber. Still other plant species have all male or all female flowers on any one plant. Some varieties of citrus are in this category. In all cases, pollination takes place when pollen from the stamens is transferred by some means to the pistils. For details, see Pollination.
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