Candlesnuff Fungus

Fruit bodies (ascocarps) are cylindrical or flattened with dimensions of 3–8 centimetres (1+1⁄8–3+1⁄8 in) tall × 2–8 mm thick. The erect ascocarps are often twisted or bent, and typically sparsely branched, often in a shape resembling a stag's antlers. Specimens found earlier in the season, in spring, may be covered completely in asexual spores (conidia), which manifests itself as a white to grayish powdery deposit. Later in the season, mature ascocarps are charcoal-black, and have minute pimple-like bumps called perithecia on the surface. These are minute rounded spore bearing structures with tiny holes, or ostioles, for the release of sexual spores (ascospores). The perithecia are embedded in the flesh of the ascocarp, the stroma, which is tough, elastic, and white. Within the perithecia, the asci are 100 × 8 μm. Ascospores are kidney-shaped, black, and smooth, with dimensions of 10–14 × 4–6 μm. The asexual spores (mitospores) are ellipsoid in shape, smooth, and hyaline.

Similar species. Many species of the genus resemble X. hypoxylon, including X. polymorpha, which is thicker and not as branched.

The fruit bodies typically grow in clusters on decaying hardwood. The fungus can cause a root rot in hawthorn and gooseberry plants.

Although not poisonous, the small size and tough texture of this fungus deter consumption. It is considered inedible by some guides.