Hygrocybe singeri, Western Witch's Hat (by Noah Siegel)

Mushroom of the Month: April, 2018

Hygrocybe singeri, Western Witch's Hat

Have you ever found a bright orange to red waxy cap, and brought it home only to find your once colorful mushroom was dingy black colored? You have found one of the blackening Hygrocybe, or the “Witch’s Hats”.

Hygrocybe singeri
They are some of our more common Waxy Caps, occuring in a wide variety of forest types; with a particular fondness for redwood or cypress duff. Our most common species is Hygrocybe singeri, recognized by its bright red, orange to yellow colors, a narrowly conical, often viscid cap, and black staining on all parts. Although the name H. conica has been used in California for fruitbodies with a dry stipe, many of these records seem to fall within the variably range of H. singeri. The joke is, you find H. conica in dry weather, and H. singeri when it is raining. However, there may be more than one species in the H. singer complex.

Hygrocybe olivaceoniger Other species of “Witch’s Hats” in California include Hygrocybe olivaceoniger; which is a smaller species with a greenish to yellow cap, without orange-red tones. It can be difficult to distinguish from small, pale H. singeri, unless one has a range of fruitbodies. It’s an uncommon species in the North Coast redwood forest.  


More distinct is H. nigrescens (sensu CA), which has larger, consistently redder caps and occurrence under hardwoods. It can be common during wet years in the Sierra Nevada foothills and upper Central Valley oak zone.

Hydrocybe nigrescens

I have also seen a spring-fruiting species in the Sierra Nevada which appears to be distinct, a tiny species in Chamise duff (Adenostoma fasciculatum) in the foothills and a one in Phil’s yard which looks closer to the European H. conica (but doesn’t match genetically).   Hygrocybe conica group (Phils)

To make matters more confounding, species of Hygrocybe is this group can have pigmentless forms. The white form of H. singeri soon takes on a grayish cast, then blackish stains overall as it ages. Hygrocybe (Hygrophorus) albinellus, described from Bolder Creek appears to be a pure white form of H. acutoconica (and likely, a legit name for our western H. acutoconica).