Dyer's mazegillPhaeolus schweinitzii

Dyer's mazegill (Phaeolus schweinitzii), also called the dyer's polypore, is a big, velvety bracket fungus at the foot of pines and other conifers. Its colours give it away: rusty brown in the middle with a bright yellow growing edge. Crafters have long used it to dye wool, which is where the name comes from. It's named after the American mycologist Lewis David von Schweinitz.

How do you identify dyer's mazegill? The fruit body is round, fan-shaped or a rosette, flat or shallowly funnel-shaped and often lobed, sometimes in two or three tiers or several fused together. It's usually 10 to 30 cm across and 1 to 5 cm thick. Young ones are sulphur yellow to orange and velvety or felty; then the centre turns rusty to dark brown while the yellow rim lasts for a while. Old ones are dark brown to almost black, dry and very light. Underneath are large, irregular pores, 1 to 3 per mm, angular and wavy like a maze, greenish yellow at first, then rusty and brown. They darken when touched. If there's a stem, it's short, thick and brown, often off-centre; on a stump the bracket may have no stem at all. The flesh is soft, spongy and wet when young, and dry, fibrous or corky when old. The spore print is whitish to pale yellow.

Where does it grow? At the base of the trunk, on the roots and root collar of living conifers, mostly pine, also spruce, larch and Douglas fir, and on stumps after the tree has died. Because it grows from the roots, it often sits in the grass a metre or more from the trunk, as if it were growing from the ground, and it swallows pine needles, twigs and grass stems as it grows. Old blackened fruit bodies can last into the new year. Fresh fruit bodies appear mostly from late summer to late autumn.

Is dyer's mazegill edible? No. It's tough and bitter, and some guides suspect it may be toxic, though we found no recorded poisonings. So don't eat it, even when young. It's valued as a dye, not as food or medicine.

Is it dangerous to the tree? It's a parasite that causes a brown cubical rot of the roots and the base of the trunk. This rot destroys cellulose and makes the wood brittle, so the trunk can snap near the base even at a fairly early stage of decay, and weakened trees blow over more easily. If you find it by a conifer near a house, road or path, ask a qualified arborist to assess the tree.

How is it used for dyeing? The colour depends on the age of the fungus and the mordant: alum gives bright yellow or gold, iron a dark moss green and copper a chocolate brown. Young fruit bodies with a bright yellow edge dye best, while old brown ones give muddy colours.

What can you mistake it for? The usual mix-up is with young chicken of the woods. But chicken of the woods is yellow and orange all over, smooth rather than velvety, forms tiers of thin shelves with small sulphur-yellow pores that don't bruise brown, and mostly grows on broadleaved trees. Cauliflower fungus also grows at the foot of pines, but it looks like a cream cauliflower made of curly ribbons and has no pores. Giant polypore and hen of the woods form rosettes at the base of broadleaved trees and have white pores, and the giant polypore's pores bruise black.