Stinkhorn Fungi — What Is That Smell?

Joey Williamson, Ph.D.
Home & Garden Information Center

Mycologists (scientists who study fungi) often describe stinkhorns with adjectives such as amazing, interesting or unique. However, homeowners lucky enough to have these aromatic mushrooms suddenly appear in the yard just before an outdoor party will often describe them as disgusting, shocking, foul-smelling or simply gross.

The presence of mushrooms in one’s flower beds is one thing, but the stench of fresh dog feces or rotting carrion is usually beyond what most folks can tolerate. Fortunately these smelly stinkhorns seem to shrivel and disappear almost as quickly as they appear.

The stinkhorns all begin as an egg-like structure beneath the soil surface, especially in wood-bark mulch beds. As it enlarges, this fungal body appears above the surface and is about the size of a golf ball. Within a period of a couple of hours, the fungal fruiting body (mushroom) erupts.

A stinkhorn fungus, Clathrus columnatus
Clathrus columnatus
Gerald J. Lenhard,

The shape of this fruiting body varies by species, and may look squid or octopus-like, or similar to an orange whiffle ball, but most commonly they will appear, well, um, like a portion of the canine anatomy.

The stinkhorn fungus, Mutinus caninus
Mutinus caninus
Chris Evans, River to River CWMA, US Forest Service.

Stinkhorns have evolved to spread their spores by attracting flies and beetles, which ingest the stinking, slimy layer containing its spores. The spore mass is olive-green to brown, and may be quickly consumed by these visiting insects. The spores are then spread far and wide.

Fortunately, stinkhorn fungi do not cause plant disease, but simply grow as saprophytes, taking their nutrients from dead plant material, such as wood mulch, buried wood debris or rotting roots. There are no chemical control measures, that is, nothing to spray to make them go away. But be relieved that they are short lived each season and may not appear in the same area again. However, to reduce the likelihood of their reappearance, hardwood bark mulch can be removed and replaced with pine needles or pine bark mulch.

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