![]() The sunflower species with the most extreme diversity in the size of UV bullseyes is Helianthus annuus, the common sunflower. We found that the size of these UV bullseyes varies extensively, both between and within species. In a recent study, we compared almost 2,000 wild sunflowers. Across the whole inflorescence, this results in a UV bullseye pattern. Sunflowers accumulate UV-absorbing pigments at the base of the ligules. However, when looked at in the UV spectrum (that is, beyond the type of light that our eyes can see), things are quite different. To our eyes, their ligules ( the enlarged, fused petals of the outermost whorl of florets in the sunflower inflorescence) are the same uniform, familiar bright yellow. All wild sunflowers, of which there are about 50 species in North America, have very similar inflorescences. What we commonly consider a single sunflower is actually a cluster of flowers, referred to as an inflorescence. How do insects see the world? Different light Despite their iconic status in popular culture (as testified by the arguably dubious honour of being one of the only five flower species with a dedicated emoji), they hardly seem the best example of flower diversity. The disconnect between what we see and what pollinators see is particularly striking in sunflowers. Many flowers accumulate UV pigments in their petals, forming patterns that are invisible to us, but that most pollinators can see. A clear example of this are ultraviolet (UV) patterns. The purpose of flowers is to attract pollinators, and it is to their senses that flowers cater. The variety and diversity is astounding - consider the duck-shaped orchid.īut as much as we can appreciate the beauty and diversity of flowers, it is quite literally not meant for our eyes. They range from colourful tulips and daisies, to fragrant frangipani and giant, putrid-smelling corpse flowers. Flowers are one of the most striking examples of diversity in nature, displaying myriad combinations of colours, patterns, shapes and scents.
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