Walking through the woods, we look up and admire the silent stalwarts competing for the sun, standing around apparently ignoring each other, trying to be a loner amongst the crowd. But under our feet, the underground network is active (1). No fiber optic-cables stuck in defined trenches here. Fungal threads stretch out in all directions to form a dense web, which can transfer water and nutrients. Young saplings that are well connected are healthier than those denied access to the web, as was demonstrated by Teste et al (2). But the most important thing that is sent along the underground is chemical information. Chemicals are the Lingua Franca, of our plant friends.
Bad news travels fast along the underground network. Zeng et al (3) poisoned a tomato plant by injection of a pathogen and stuffed its top in a plastic bag to keep it quiet. The underground was buzzing though, and the neighbors quickly rallied and activated 6 defensive genes. They weren’t going down without a fight!
Nepotism has a tendency to occur everywhere and plants are not immune to it. Dudley and File (4) watched while American sea rocket helped its younger brothers and sisters to a place in the sun. But it was a ruthless empire builder if planted among different species. Then its roots rushed out to grab the lion’s share of food and water. Some plants can also work harder in their defense against insect attack if backed up by their family. Being surrounded by their kinfolk stiffens their backbone.
Not all plants have a “family first” make up and companion plants are out there to be cherished. Peas and beans, for example, in a fit of global generosity, employ micro-factories manned by bacterial workers busily fixing nitrogen for the enjoyment and delectation of others.
Now, this primal networking is both fascinating and obvious, if you think about it. I can envision all those tender roots and shoots communicating through molecular media, both below and above ground, while we stand mute and dumb, until we learn to listen.