Trees are slow, like Ents. The electrical impulses that pass through trees travel at a rate of one-third of an inch per second.
Why do trees need electricity? According to Peter Wollheben (The Hidden Life of Trees), they need electricity to talk to each other.
He's not kidding: “trees need to communicate, and electrical impulses are just one of their many means of communication. Trees also use the senses of smell and taste for communication. If a giraffe starts eating an African acacia, the tree releases a chemical into the air that signals that a threat is at hand. As the chemical drifts through the air and reaches other trees, they ‘smell' it and are warned of the danger. Even before the giraffe reaches them, they begin producing toxic chemicals. Insect pests are dealt with slightly differently. The saliva of leaf-eating insects can be ‘tasted' by the leaf being eaten. In response, the tree sends out a chemical signal that attracts predators that feed on that particular leaf-eating insect” (vii-viii).
Trees talk because they're sociable: “The trees in a forest care for each other, sometimes even going so far as to nourish the stump of a felled tree for centuries after it was cut down by feeding it sugars and other nutrients, and so keeping it alive. Only some stumps are thus nourished. Perhaps they are the parents of the trees that make up the forest of today. A tree’s most important means of stay- ing connected to other trees is a ‘wood wide web' of soil fungi that connects vegetation in an intimate network that allows the sharing of an enormous amount of information and goods” (viii).