All the plants around you are talking to each other. The trees and the shrubs and the flowers are passing information back and forth, with serious life and death consequences. They’re using a giant network of fungi - one so pervasive and powerful that some scientists have started comparing it to the Internet. They’re calling it the "Wood Wide Web". The so-called Wood Wide Web is made up of what are called |mycorrhizal fungi". There are many different types of mycorrhizal fungi, but generally, these little guys will grow on the roots of plants and provide them with water and nutrients—like nitrogen and phosphorus in exchange for sugars from the plant. While they’re incredibly thin, the threads of the fungi can be up to 1000 times the length of a tree root. This allows the fungi to connect together many different plants. Once connections are made, the fungi can act almost like the neurones in our brain, transporting signals from plant to plant. And these networks are everywhere. It’s estimated that around 90% of land plants are connected to some kind of mycorrhizal network. They can help each other out in times of stress. For example, during the fall months, when paper birch trees lose their leaves and can’t produce sugar, Douglas-fir trees may shuttle them nutrients through the fungal network. And in the summer, when paper birch trees have lots of leaves, they send sugars to young Douglas fir saplings growing in their shadows. Plants can also warn each other of danger. Douglas fir trees connected by a fungal network can alert their ponderosa pine neighbours if they’re attacked by budworms. In response, the neighbouring ponderosa pine trees will produce insect-repelling chemicals - even though they haven’t been directly exposed to the insects themselves. Mycorrhizal fungi can also enable parental care of among plants. Some adult trees will help out their younger relatives by sending those seedlings more nutrients through the fungal network than they send to strangers. The adults may even make more room for them in the soil by reducing the number of their own roots. But not everyone is so generous. Much like our internet, things can sometimes get a little nasty on the Wood Wide Web. Take Black Walnut trees, for example. They can spread poison through the network, hindering the growth of their neighbours. And the fungi making up the network can be just as tricky. Mycorrhizal fungi tend to pick favourites. They may share resources with one species of tree, but bleed another species dry without giving anything back in return. The fungi may also judge a plant's health. If they think it’s too weak or sick, they may not allow it to receive nutrients or danger signals from the network. Now, we’re only beginning to understand how complex these relationships get. But imagine the possibilities for agriculture and forestry. If we find out certain species share well across the network, maybe we can plant them near each other to yield better harvests or grow healthier forests.