A Tree-Man is as tall as a grown oak and looks, at first, like one, with a trunk of deep-ridged bark, a crown of branches, and roots spreading wide. Look again and the trunk has a shape: the line of a back and shoulders, the hint of a face in the bark, high up, with two dark knots for eyes and a split for a mouth, and the branches are arms, ending in twig-fingered hands. Moss hangs in its crown and flowers open along its limbs. It moves very slowly, a bough lowering over a path in the time it takes to cross it, and when it speaks it is a deep creak and groan, like a tree in a storm. It smells of wet bark and leaf-mould.

They stand in the oldest forests of the Verdant Expanse, often at the edges of its gates and along its root-bridges, each rooted in one place for as long as anyone knows.

They guard the Expanse. A Tree-Man watches whatever passes beneath it, and lets most of it pass; what harms the forest, cutting, burning, or carrying growth away, it stops, by closing its branches, raising its roots, or bringing a bough down. It is slow to rouse and slow to calm. It speaks rarely, and seems to listen to the root-network more than to anyone in front of it.

It can move its limbs and roots, slowly but with the strength of a tree, enough to crush a man or close a path. Through its roots it feels harm to the forest far away, and the whole Expanse feels harm done to it.

Tree-Men are not born. They are beings, some say visitors, who stayed and rooted, and they grow for as long as the Expanse does.

Their fallen wood is the Expanse’s living wood, stronger than steel. Their danger is to anyone who harms the forest within their reach.

Travellers' tales of walking trees on the Expanse have fed the forest stories of Caeldon, where an old tree with a face in its bark is sometimes said to be watching. Whether any Tree-Man has ever stood on Caeldon is not known.