You can tell a lot about a tree from the company it keeps. James Nardi guides you through the innermost unseen world that trees share with a wondrous array of creatures. With their elaborate immune responses, trees recruit a host of allies as predators and parasites to defend against uninvited advances from organisms that chew on leaves, drain sap, and bore into wood. Microbial life thrives in the hidden spaces of leaf scales, twigs, and bark, while birds, mammals, and insects benefit from the more visible resources trees provide. In return, animals help with pollination, seed dispersal, and recycling of nutrients. The Hidden Company That Trees Keep blends marvelous storytelling with beautiful illustrations and the latest science to reveal how the lives of trees are intertwined with those of their diverse companions.