Fringy flowers are hard to dunk

What good is fringe to a flower? People have traditionally considered fringe as merely part of the display for pollinators, says Joseph E. Armstrong of Illinois State University in Normal. It does enhance the flower’s visual appeal, but Armstrong is convinced that fringe has another role.

Bobbing on water, a hairy-edged flower is slow to sink and quick to recover from a dunking, says Armstrong.

Clumps of hairs lining the edges of the blooms of the water snowflake, Nymphoides geminata, increase the aquatic flower’s perimeter without adding much weight, Armstrong notes. He tested the force necessary to sink flowers before and after he trimmed their fringe. Pushed down at their centers, blooms with intact fringes required nearly 50 percent more force to dunk, Armstrong reports in the February American Journal of Botany.

When Armstrong did push fringed flowers underwater, they folded inward to a bud’s shape and trapped an air bubble inside. When Armstrong let the submerged flowers bob back to the surface, the lobes of the flower flared open with reproductive organs dry and ready for insect visitors.

Armstrong compared these fringed flowers with those of aquatic cousins in the same genus. Flowers with edges that thin out to a membrane or end in ruffles didn’t fare well after submersion. When these flowers are dunked and then released, parts of their flowers remain stuck underwater and their reproductive organs get drenched.

Armstrong says fringed flowers can support the weight of a chunky pollinator, such as a bee, without dipping below the water line and getting the guest’s feet wet.