Once I first saw Dendrocollybia racemosa, commonly known as the branched shanklet, I knew I stumbled upon a fungus worthy of being featured on an edition of Fungi Friday. It is just so bizarre looking! Its peculiar appearance is matched by its unique ecology. Additionally, this small pale mushroom is exceedingly rare. The encyclopedia of life claims that in the pacific northwest, only 33 occurrences have been documented. I’m sure it has been found more than 33 times, but still, this is a really low number for documented occurrences. In Europe, its rarity has placed it amongst other red listed species, being categorized as near threatened. For me, this mushroom is a bucket list species. One day I will find this oddity in the wild, and triumphantly smile over it. For now, I can only learn about it.

D. racemosa grows on decaying fruiting bodies of other gilled mushrooms. It’s not truly parasitic, because it feeds on decomposed mushrooms that have already released most of their spores. It’s a saprotroph, only instead of decomposing wood, it enzymatically breaks down mushrooms from the genera Russula and Lactarius. Most of the time, its host is so decomposed, one cannot identify it down to species. 

The most distinguishing feature of this mushroom are its lateral branches coming off of its stipe. At the end of each branch lies translucent conidiophores which form asexual spores called conidia. The gills underneath its cap still produce sexual spores, but most of the time, when this fungus produces robust, asexual braches, its cap growth becomes stunted. From the pictures I have found, it looks like when there is a fully formed gilled cap, the branches become reduced. What decides either morphology? I really don’t know. It could simply be a genetic anomaly, or it can stem from outside influences associated with its habitat.

Recently, this mushroom has been renamed, as genetic analysis confirmed it was more distantly related to other Collybia species. Now, there are only 3 Collybia species, and the newly formed genus called Dendrocollybia which contains but one species-the oddity featured in today’s post. Like its closely related cousins, D. racemosa grows out of fungal structures called sclerotia, that reside in the buried remains of their fungal host. 

This inimitable fungus is the only fruiting body in this massive kingdom that produces asexual branches. It’s a fungus I long to find in nature, and I am confident I will someday uncover it. When I make it to the pacific northwest, I will scour the forest floor for any signs of Russula and Lactarius species. Hopefully I can spot this small, pale, branched fungus growing from its sclerotia, buried in the remnants of its decomposed host.

[Link 1] [Link 2] [Link 3]