By Isabel Cantu
Honey is a sweet treat easily paired with a multitude of things: toast and tea are two examples. Many of us are indebted to the creatures that help produce it, bees especially. We’re told that a flower’s color, scent, and shape help to entice pollinators, but there is an even more up-close method flowers employ to lure them in. Markings we often cannot see act as hidden signals of pollen’s location, dotting and lining flower petals to lead straight to the sugary center. These nectar guides are usually only visible in UV light, and since bees have vision extending from yellow to ultraviolet, they get by just fine.
Largely unbeknownst to the human eye, these distinctive markings on a flower’s petals serve to highlight nectar to oncoming bees and make the pollination process much more efficient. They can come in a multitude of different patterns and colors, some of which are visible to humans as light colors, such as the white arrow-like nectar guides on the South African Lapeirousia oreogena or the dark purple streaks on the Penstemon palmeri. The plainest flowers in visible light can take on a completely different appearance in ultraviolet light, making this technique of attracting bees very worthwhile. Some flowers do not just have a single nectar guide either; when attempting to attract several pollinators, guides can overlap and entice several creatures.
Hummingbirds, hoverflies, and hawk moths are attracted to nectar guides in addition to bees, making the aforementioned overlap a worthwhile adaptation. While some patterns are ultraviolet the others are in the visible spectrum to appeal to a range of visions. In a 2011 study that tested the significance of nectar guides, it found that removing them significantly deterred pollinators from staying long on the flower despite being attracted to its color and shape from a distance. It was also observed that while petal shape can influence the speed at which a bee finds a flower’s nectar, nectar guides help them no matter what shape a flower may be.
Loyalty is quite important in the world of pollination. If a bee or bird is loyal to a specific species of flower, both sides benefit--the pollinator from a stable food source and the flower from a reliable pollen transfer. Anything to help a bee find nectar faster will capture its attention even when there is very little, or no, reward at the end of it. It was found that a bee continued to visit a flower with a nectar guide despite it having no pollen or nectar, proving just how enticing these patterns can be. With the help of these guides, bees don’t have to worry about missing nectar or staying for too long on a single flower.
A pollinator choosing a plant wisely will always go for an option that gives them a quick reward--it saves valuable time and leads them swiftly to the nectar they need. There can be a single nectar guide on a flower or multiple extending into various light ranges, but all have been shown to be incredibly effective in reeling in pollinators and keeping them loyal to a plant species. While we aren’t always able to see these splotched and dashed patterns on petals, their effects are a reminder that not everything is as it seems.
Works Cited
Image Credit:
No changes were made, File:Mimulus nectar guide UV VIS.jpg - Wikimedia Commons, License: Creative Commons Legal Code
Educational Questions:
Q. Why can’t we see most nectar guides?
1. The majority of nectar guides are only visible in UV light and appear as darkened patterns, but some are indeed visible to us and can appear as colored streaks along a flower’s petals.
Q. What creatures are attracted to nectar guides?
2. Bees, birds, hawkmoths, and certain types of flies can be attracted to a flower’s nectar guides, and flowers will often display overlapping nectar guides along their petals to attract this range of pollinators.
Q. How exactly do nectar guides make the pollination process more efficient?
3. Nectar guides let pollinators know exactly where a plant’s nectar is, so they don’t need to spend an excessive amount of time with a single flower looking for it. Less expended energy with a flower species means that pollinators will keep coming back, which benefits both parties involved.
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