Exidia zelleri

The basidiocarps of E. zelleri are gelatinous, button-shaped to top-shaped and attached to the wood at a point, sometimes coalescing to form effused, irregular masses up to 8 cm across. pale violaceous grey to grey brown, darkening with age. The surface is sparsely to densely covered in small papillae (pimples).^[1][2]

The translucent hyphae are thin-walled and form clamp connections. Basidia are elliptical and consist of four longitudinally septate cells. Basidiospores are allantoid (sausage shaped), 16 to 19 by 5 to 6 μm, with thin, smooth walls.^[2]

Fruit bodies of Exidia crenata and Exidia recisa also occur on broadleaved trees in North America, but are typically reddish to orange-brown and lack papillae on the surface. Exidia glandulosa has papillae, but is typically blackish brown to black.

Exidia zelleri was originally described from Oregon and has also been recorded from California and British Columbia. It was originally collected on dead wood of Sambucus, but has subsequently been reported on other broadleaved trees.^[3]