Nectar is renowned as nature’s sweetest brew, but to do its job it needs a touch of bitterness too.
Nectar feeders such as moths and hummingbirds are attracted by the sweetness, but it’s not in the plant’s interest for them to stay too long. If they do, and drink all the nectar in one go, there’ll be none left for subsequent visitors, leaving fewer opportunities for the plants to spread their pollen. “The trick is to attract the greatest number of pollinators for the least amount of nectar,” says Ian Baldwin of the Max Planck Institute for Chemical Ecology in…
