In the same family as the Venus flytrap (Droseraceae), sundews comprise a very different group of carnivorous plants. Sundews secrete glistening drops of a viscous, sticky substance, called mucilage, through glands on “heads” all over their leaf surfaces. This appearance gave them the genus name Drosera, Greek for “dewy.” Globally distributed, Drosera were the first carnivorous plants described. First inaccurately labeled a “moss” in 1554, by the late 1700s several botanists reported seeing flies imprisoned within the leaves and noted the leaves could bend, although for decades the idea that the plant moved, let alone the idea that any plant structure could kill and absorb an insect, was heatedly debated. The debate ended when Charles Darwin published definitive experimental results in 1875; the plant does move to entangle, and kill, its prey.
Another impressive group of carnivorous plants is the “pitcher plants,” which have distinctive “pitchers,” cup-like formations for trapping insects. These plants’ predecessors likely had slightly cupped leaves that trapped enough water so that when an insect landed, it would be trapped by surface tension, drowned, and digested by bacteria. Nutrients released from the decayed insects were absorbed by the plant leaves, creating an evolutionary preference for cup-like leaves. Modern-day pitchers have several features that enhance trapping: smooth, vertical surfaces that cause prey to slip inside; transparent regions that make it unclear where the exit is; and sweet-smelling, attractive nectars.