No. 16: Summer 1981
Plants are usually considered rather passive to environmental forces, but careful observation show that they fight back against predators in subtle ways. Williams and Gilbert, for example, have found that a number of Passiflora species, which are heavily defoliated by the larvae of Heliconius butterflies, have developed tiny structures that closely resemble in size, shape, and color the eggs of these butterflies. Heliconius butterflies, when searching for likely plants on which to lay eggs, tend to avoid plants that already have eggs on them. The plants' fake eggs, then, help protect the plant from predation.
(Williams, Kathy S., and Gilbert, Lawrence E.; "Insects as Selective Agents on Plant Vegetative Morphology....."; Science, 212:467, 1981.)
Comment. We have heard over and over again about Nature's "marvelous adaptations," but it is still difficult to imagine chance-driven evolution of fake eggs of just the right size, shape, and color. How many shapes and colors were tried before the plants got it right?