South American vine is a masterful mimic

The world is full of organisms that can change themselves to be more like something else. There’s the chameleon, of course, which can alter its coloring to blend into the background. In the insect world, you’ll find butterflies that mimic toxic brethren, sticks that are really insects and mantises that look like orchids. Lyrebirds can make themselves sound like all kinds of odd things, including car alarms. And then there’s that guy who sang “Let It Go” in the voices of different Disney and Pixar characters.

Plant mimics are a bit harder to find. (Especially when some of them look like rocks.) But two scientists in Chile have discovered a species of vine that is able to make itself not only look like one host plant but actually mimic several different tree hosts. Ernesto Gianoli of the Universidad de La Serena and Fernando Carrasco-Urra of the Universidad de Concepción report their findings April 24 in Current Biology.

The vine Boquila trifoliolata can be found climbing up other plants in temperate rain forests of Chile and Argentina. The vine produces clusters of three leaflets, but the researchers noticed that the shape, size, color and orientation of the leaves weren’t always the same. They took a closer look at 45 vines growing on 12 different host tree species.

When a vine grew on a tree with thin, pointy leaves, its leaves were thin and pointy. On a tree with short, stubby leaves, B. trifoliolata’s leaves were short and stubby. The vine’s leaves indeed changed shape, color, size, thickness, angle and other attributes to match those of its host, the researchers found. Only when the vine was growing on its own or on a part of a tree without leaves did it show its “standard” leaves.

This mimicry pays off — vines that don’t grow on trees or attach themselves to supports that don’t have leaves are more likely to get eaten by small herbivores such as weevils and leaf beetles, the researchers found.

Just how the vine pulls off these impersonations isn’t clear, however. “We currently lack a mechanistic explanation for this unique phenomenon,” the scientists write. B. trifoliolata doesn’t even have to be touching its host to mimic it, so the vine can’t be sensing something directly from the host tree. But the trees might be emitting some kind of chemical signals that the vine picks up. Or there might be some kind of gene transfer going on, though the researchers admit that that hypothesis is even less plausible than the first.