Black and white Clitocybula

Clitocybula is a genus of small to larger clitocybe- or collybia-like mushrooms that occur on wood or woody debris and have whitish amyloid spores. Some of the species grow in clusters, such as C. abundans (Peck) Singer, and have adnate to slightly decurrent gills. C. atrialba is a western species that occurs singly on the (sometimes buried) wood of alder and perhaps other hardwoods. It can be very common in some years, but totally absent in others. It is an elegant slender-stiped mushroom with a funnel-shaped, dark smoky to blackish brown, matted fibrillose to furfuraceous cap, distant, decurrent, pale grayish gills that end at a collar-like line on the stipe apex, and a scaly to furfuraceous stipe that is colored like the cap, enlarged below, and often bears white strands at its base.