A colorful quest

CBS undergraduate Leah Hallett searched for plants that produce colored nectar at the CBS Conservatory.
December 15, 2021

Finding colored nectar sounds simple, and for pollinators it likely is. For humans, not so much. It takes close examination and an eye for detail. Leah Hallett has many spent hours in the CBS Conservatory & Botanical Collection nectar spotting. So far, the Plant and Microbial Biology major has identified a handful of these floral renegades. 

Most plants produce clear nectar or no nectar at all. Nectar functions as a reward for pollinators, a “thank you” for doing the work of moving pollen around. Not a lot is known yet about why plants produce colored nectars, but Clay Carter, a professor in the Department of Plant and Microbial Biology is looking into it. Hallett joined the Carter lab earlier this year. The research also has practical applications since some of these nectars could become more sustainable sources of dyes for the food and textile industry

“We’re trying to see how colored nectars influence pollinators and what kinds of interactions they have between each other,” says Hallett, “and also to determine what the pigments are in these nectars.”

But the first step is finding the plants with this relatively unique type of nectar. “There are only 68 species known to make colored nectars, but since nectar is often overlooked as a trait, we figured that there are likely many more out there,” says Clay Carter, a professor in the Department of Plant and Microbial Biology. “Leah found several 'new' species with colored nectars in her first hour or so of looking in the Conservatory's collection. To me, this suggests there are hundreds if not thousands of species out there with colored nectars, many of which likely have novel chemistries and associated plant-pollinator interactions.”

Hallett started her project by going through each room in the Conservatory and writing down the names of every plant with a flower and then used a pipette and started looking at the nectar.

“I found this one family—neo-tropical blueberries—the first day. Now, I have six species with colored nectar,” says Hallett. The flowers in question were photographed with a special camera that captures images that match up with the spectrum of colors a pollinator can see. The next step is to analyze the nectar pigment. For Hallett, the search continues. —Stephanie Xenos