- A flower in which one or more members of a whorl, or of several floral whorls, differ in form from other members. Irregular flowers, such as those of the violet or the pea, are often bilaterally symmetric. The pea has one large upper petal above, two free petals on the each side, and two petals fused together in a keel shape below. Compare regular flower.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.