Moss grows in low, close cushions and mats, from a finger’s depth to a hand’s, of tiny leaves on threadlike stems. Most is green, from bright yellow-green in light to a deep, near-black green in shade; some turns rust-brown in dry weather and greens again with rain. Wet, it is cold and spongy and squeezes out water like a cloth; dry, it is springy and crisp. In season it puts up thin stalks with small brown capsules. It smells of wet earth and green, and it swallows the sound of a step.

Lichen is flatter and slower: grey-green, sage, mustard-yellow, or orange crusts and rosettes the size of a coin to a plate, pressed to stone and bark, with some kinds standing up in small grey tufts or hanging in beards from branches. It is dry and papery to the touch, and has almost no smell.

Moss wants shade and wet. On the Elderweald floor it is woven with living root and leaf-mould into the deep, soft root-mat, a ground that holds water like a sponge and gives a little under every step (see Living Root). It furs the trunks of the great trees low down, the hollowed boles of the groves, and the upper treads of the Sunken Stairs, which have thickened into uneven, moss-furred shelves. Lichen wants light and clean air, and grows on exposed rock, walls, and old bark where moss cannot hold.

Moss and lichen are met in the planes and zones as well. In the Verdant Expanse a thick carpet of moss and ferns swallows footsteps and cushions falls, and lichens creep over metal and stone. The shifting ground of the Probability Fog turns to soft moss and back again. The moss that never grows tall around the Ageless Spring is told with Ageless Spring Flora, and the moss and sand floor of the Drowning Garden with Drowning Garden Flora. Two lichens have their own pages: the marker lichen of the Witnessfields' inscribed stones and the rime lichen of the Frost-Bound’s ice.

Moss grows slowly, keeps water, and outlasts drought by drying and waiting. Lichen grows more slowly still, a little each year, and lives on almost nothing but air, light, and rain. Both creep over whatever is left still: a fallen trunk, a step nobody walks, a wall nobody cleans. In the Verdant Expanse that creep is fast and hungry, and stone and metal are overgrown and slowly consumed.

Moss spreads by spores and by broken pieces that root again, and a mat lives on for as long as the ground stays wet, dying back at its surface and growing on from below; its dead lower layers become the leaf-mould and peat that feed the forest floor and, washed down, the fungus of the Roothollows. Lichen lives very long, and a broad crust on a stone is reckoned as old as the wall it grows on.

Moss is bedding, padding, and wound-dressing, and it stops gaps in timber and stone. Lichens give dyes. The marsh school of Nature Magic called the Mossbound Archive studies the symbiosis and decay that moss lives by. Neither is dangerous, though moss makes stone treads slick, and a slip on a moss-furred stair or a hollow hidden under the root-mat is the forest’s commonest small injury. Damp that breeds mould is fought by wards in sickrooms (see Warding); the smell of mould is among those of the Lost Archive.

Moss stands for age left alone. The Wood Elves read a moss-furred stair or bole as proof that no one has hurried it, and the oldest groves smell of old wood and wet moss. The Stone-Warden is shown with moss and lichen in the crevices of his granite skin, and a lichened stone is taken in many places as a stone that has held. The Verdant Expanse teaches the other face: travellers are warned that what moss will cushion it will also cover.