Shiny, Sparkly … Plants?

Sparkly skin helped Edward attract Bella … but does the same thing work for plants and pollinators? New research indicates that the answer to this question is a resounding “yes.”

flowers under normal and UV light

Flowers seen under UV (top) and normal (bottom) light. (Photo credit: Tim Kinsman/Science Source)

Many plants rely on insect pollinators. Certain floral traits, such as highly contrasting color patterns, help attract these pollinators. While these patterns are sometimes visible to the human eye, in many cases these patterns, often called nectar guides, occur in the ultraviolet range of the spectrum. These wavelengths of light are visible to certain pollinating insects, such as bumblebees.

In addition to color patterns that are only visible under ultraviolet light, some plants also exhibit a trait called iridescence. Iridescence in plants was unknown to scientists until 2009, when scientists at the University of Cambridge discovered that certain plants exhibited this phenomenon. The term iridescence comes from the Greek and Latin word isis, which means rainbow. Objects that are iridescent are typically described as having a shimmering, sparkling, or rainbow-like appearance. In addition to giving flower petals a rainbow-like appearance, iridescence also helps to enhance the natural pigmentation of the flower, making it particularly bright and saturated in color

Iridescence in plants occurs due to tiny grooves on the surface of flower petals. These ridges diffract light and change the way the petals look depending on the angle at which they are viewed. In other words, the color of the petals appears to change as you look at them from different angles. Bumblebees have the ability to perceive iridescent signals and can use them to identify particularly rewarding (that is, nectar-filled) flowers. Researchers think that the tiny grooves that make the flowers surface iridescent may also help insects to grip onto the plant after landing.

One example of a plant that exhibits iridescence is Hibiscus trionum, also known by the common name flower-of-an-hour. The flowers of this plant have white petals with a red patch at its center, which forms a bulls-eye pattern. The red patch is iridescent. Research indicates that the bulls-eye pattern helps to increase the attractiveness of the flower from a distance; scientists think that due to the directionality of iridescence, it may help to properly orientate pollinating insects on the flower once they have landed.

Another example of plant iridescence involves mimicry. Ophrys orchids use sexual deception of male wasps and solitary bees for pollination. A portion of the flower is shaped like the closed wings of a female wasp to attract males; this portion of the plant is also iridescent.

Iridescence in plants is not always intended to attract pollinators. Tropical rain forest research by University of Cambridge scientists indicates that some plants, which grow in the deep shade of the forests understory, have leaves that exhibit a blue iridescence. Though the exact function of this iridescence is unknown, scientists hypothesize that this iridescence helps to camouflage the plant from herbivores.

In an article about the research published in the Journal of the Royal Society Interface, the scientists, led by Dr. Katherine Thomas, wrote, The iridescence produced on the leaves of plants could act to confuse moving insects and herbivores by camouflaging the shape and edge of the leaf and making it difficult to form a target search image. Alternately, the iridescence may serve to deter herbivores from all other food sources that iridescent leaves are not recognized as food, or avoided.

More to Explore
Contributions of Iridescence to Floral Patterning
How Does Your Garden Glow?
Iridescence: A Functional Perspective
Function of Blue Iridescence in Tropical Understory Plants

Comments

  1. Emma Brown says:

    I think its pretty and I would want to buy some

  2. OMG. The first sentence of a school article and there is a Twilight reference… Dx

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