The social behavior of kin recognition has been well studied and understood in the animal kingdom, and recently evolutionary biologists have begun to explore this phenomenon in the plant world.

It is widely recognized that plants have the ability to detect and respond to plants around them. However, the question of whether they have kinship recognition capabilities and whether or not plants “act altruistically” towards their kin is now under question.

Ph.D. candidate Guillermo Murphy along with Dr. Susan Dudley performed a study on the kinship behaviors of the plant known as Impatiens pallida, commonly referred to as yellow jewelweed. Impatiens pallida are a likely candidate for altruistic kinship recognition because they have been known to display strong responses to plants growing aboveground in close proximity.

The study recorded the response of jewelweed with neighboring strangers, relatives and no plants at all. When Impatiens pallida were planted next to strangers they elicited a competitive response of increasing their resource allocation to their leaves, instead of their roots and stems. The reason for this is that by producing more leaves the plant has above ground it can improve its ability to acquire a limited resource, in this case light, as well as negatively impact the plants around them by shading them.

One the other hand, when Impatiens pallida were planted next to relatives the elicited response was to elongate their stems and increase branching rather than increasing the breadth and shading of their leaves.

Murphy and Dudley concluded that this was the plants behaving altruistically towards their kin; attempting to increase their resource reach without behaving detrimentally to those around them.

The one limitation that Murphy and Dudley were able to glean was that Impatiens pallida can only discern kin from foe by root interaction. This means that any aboveground response from the plants would have to be triggered by an underground cue.

Thus the study concluded that plants can indeed be altruistic if the conditions for sensing one another are right. This finding changes the way the scientific community views plants; they are now known to be social creatures. Plants are indeed aware of their surroundings and socially capable of more than we had originally expected.

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Discussion question: What sorts of trends have been found in the animal community regarding kinship thought ought to be tested and studied for plant parallels?

Article link: http://www.sciencedaily.com/releases/2009/11/091111092047.htm
Journal link: http://www.amjbot.org/cgi/content/abstract/96/11/1990