The basics of flower structure are straightforward. A “typical” flower (Figure 1) has four whorls of floral organs arranged in stereotypical order: sepals (lowermost and outermost), petals, stamens, and, finally, one or more carpels (pistils) located in the innermost (or uppermost) position. This is not rocket science. Names of these floral organs and their relative placement within the flower can be grasped readily by schoolchildren. Also “typical” but seldom emphasized in elementary lessons is the fact that the organs of each successive whorl occupy alternate radii; i.e., petals are routinely positioned between sepals, and stamens (if only one whorl) are positioned between petals. Said another way, successive floral organs typically occur on alternate radii.
Copyright © 2019, Virginia Native Plant Society. This article first appeared in Sempervirens Quarterly (Spring 2019), 6-7.
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Hayden, W. John. "Unique Features of Ceanothus Trace to Earliest Stages of Flower Development." Sempervirens Quarterly Spring 2019, 6-7.