If you have read the previous post about how yucca flowers are pollinated by the yucca moth you might wonder how the moth is able to navigate to flowers in the dark. Well, it’s fairly well known that many insects have visual capabilities outside of the visible portion of the electromagnetic spectrum. What many people may not be aware of is that many parts of flowers have evolved to take advantage of an insect’s visual range, especially in the UV or ultraviolet part of the spectrum.
It just so happens that Yuccas have “UV-coded” their stamens (male reproductive part of the flower) and especially the anthers, which produce the pollen. Take a look at the UV photograph below of the stamens from a Yucca flower. The bright white parts of the stamens are the anthers.
I would be willing to bet that the yucca moth has visual capabilities in the UV range and is assisted in its pollination duties by the UV-visual anthers. Would other insects be drawn in as well? Maybe. But there are a couple of things to consider. First, many insects are not active at night. Second, yucca flowers do not have nectaries which provide nectar as a reward for transferring pollen to other flowers. Most insect-pollinated flowers have nectaries to provide a food reward for the insect. For yucca flowers the reward or offering to the moth is the flower’s ovules or immature seeds.
Just another interesting aspect of the natural history of Yucca torreyi. Thanks to Monique Reed of Texas A&M University for suggesting this topic and providing the photo. Photo credit goes to Robert Corbett.