February Mushroom of the Month:
Trichaptum biforme \\ Violet-toothed Polypore
Trichaptum biforme, the violet-toothed polypore, is a hardy bracket fungus that can be found on dead hardwood all year long. This species is most often found on logs and stumps of trees such as birch, maple, and beech, where it plays an important role as a white-rot fungus, breaking down lignin and returning nutrients to the forest.
What makes Trichaptum biforme especially distinctive is its pore surface. Although it’s technically a polypore, its pores don’t stay neatly round for long. In young specimens, the underside shows small, angular pores that often form maze-like or zig-zag patterns. As the fungus matures, these pores quickly erode and break apart into jagged, tooth-like or spine-like structures. This transformation gives rise to its common name, the “violet-toothed” polypore.
Color is another key feature. When fresh, the pore surface is typically violet to purple, especially near the growing margin of the bracket. Over time and with weathering, these vivid colors fade to tan or brown, though moisture can sometimes revive the purplish tones. The fungus grows in thin, shelf-like brackets, and the underside becomes unmistakably rough and toothy rather than smoothly porous.
In North America, Trichaptum biforme is a common sight on dead hardwood and can be distinguished from look-alike polypores such as Turkey Tail (Trametes versicolor), which has a smooth, white pore surface rather than a toothed one. Its tough, leathery texture allows it to persist through cold weather, making winter an ideal season to observe both its structure and its unique transformation from pores to teeth.
Text and photos by Liz Weinstein.
