Current Weather
The Spy FM

Do Plants Smell Other Plants? This One Does, Then Strangles What It Smells

Filed by KOSU News in Science.
May 24, 2012

“Plants smell,” says botanist David Chamovitz. Yes, they give off odors, but that’s not what Chamovitz means. He means plants can smell other plants. “Plants know when their fruit is ripe, when their [plant] neighbor has been cut by a gardener’s shears, or when their neighbor is being eaten by a ravenous bug; they smell it,” he writes in his new book, What a Plant Knows. They don’t have noses or a nervous system, but they still have an olfactory sense, and they can differentiate. He says there’s a vine that can smell the difference between a tomato and a stalk of wheat. It will choose one over the other, based on…smell! In a moment I’ll show you how.

This talented plant is commonly known as the dodder vine. It’s a parasite; tomato gardeners know it and hate it.

Here it is at Penn State University — look for the stringy, wiggly thing on the left — sniffing. Notice as it grows from a seedling, it moves in small, lazy circles, like hands groping in the dark, and then, gradually, it leans toward the stalk of the tomato plant — which it then entwines, gouges, sucks and strangles.

Ewww, you say. (I am assuming you are pro-tomato). But how do we know the vine is “smelling” that tomato plant? Enter Dr. Consuelo De Moraes, a biologist at Penn State. With her colleagues, she put the dodder plant to the test.

The Fake Tomato Experiment

When she placed a dodder vine between an empty pot and a fake plant with no odor, the dodder didn’t lean toward either…

The Real Tomato Experiment

When she put a real tomato plant next to a dodder, it leaned in the tomato’s direction, whether the tomato was (a) well lit, (b) in the dark, or (c) out of view.

The Dodder-In-A-Box Experiment

When she had her students put both the dodder vine and the tomato plant into a box connected by a hose, like this…

…the air could blow from one box to another, and over and over again, the boxed-up vine always leaned toward the tube hole, toward the air wafting in from the tomato…

With sight and touch eliminated, it’s fair to conclude the dodder was sensing odor to find food.

But now comes the Finicky Eater part. The dodder will also eat (or suck nutrition from) wheat plants. But it prefers tomato. We know this because when Professor De Moraes & Co. placed a dodder an equal distance from a wheat plant and a tomato plant…

…the dodder consistently went for the tomato. Which is interesting, says Professor Dan Chamovitz, because at the chemical level, wheat and tomatoes, he says, “are rather similar,” but tomatoes combine three chemical smells that attract dodders, whereas wheat has only one attractant. That slightly different cocktail of odors pulls the dodder to the tomato, which means that plants can make odor distinctions that are quite subtle.

Yeah, But Is This The Same Thing As “Smelling”?

Well, says Chamovitz, “Plants obviously don’t have olfactory nerves that connect to a brain that interpret signals…but [some plants] do respond to pheromones, just as we do. Plants detect a volatile chemical in the air, and they convert this signal (albeit nerve-free) into a physiological response. Surely this could be considered olfaction.”

Tomato plants, if they had necks, would be nodding fervently.

Daniel Chamovitz’ book is called What A Plant Knows: A Field Guide to the Senses. [Copyright 2012 National Public Radio]

Leave a Reply

9AM to 10AM The Takeaway

The Takeaway

A fresh alternative in morning news, "The Takeaway" provides a breadth and depth of world, national and regional news coverage that is unprecedented in public media.

Listen Live Now!

10AM to 11PM On Point

On Point

On Point unites distinct and provocative voices with passionate discussion as it confronts the stories that are at the center of what is important in the world today. Leaving no perspective unchallenged, On Point digs past the surface and into the core of a subject, exposing each of its real world implications.

View the program guide!

11AM to 12PM The Story

The Story

The Story with Dick Gordon brings the news home through first-person accounts. The live weekday program is passionate, personal, immediate and relevant to listeners, focusing on the news where it changes our lives, causes us to stop and rethink, inspires us.

View the program guide!

Upcoming Events in your area (Submit your event today!)

Streaming audio and podcasts

Stream KOSU on your smartphone

Phone Streaming

SmartPhone listening options on this page are intended for many iPhones, Blackberries, etc. with low-cost software applications available to listen to our full-time web streams, both News on KOSU-1 and Classical on KOSU-2.

Learn more about our complete range of streaming services

We're perfecting the patient experience - Stillwater Medical Center